71 results on '"Loic Salles"'
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2. The Tribomechadynamics Research Challenge: Confronting Blind Predictions for the Linear and Nonlinear Dynamics of a Novel Jointed Structure with Measurement Results
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Malte Krack, Matthew R.W. Brake, Christoph Schwingshackl, Johann Gross, Patrick Hippold, Matias Lasen, Daniele Dini, Loic Salles, Matthew Allen, Drithi Shetty, Courtney A. Payne, Kai Willner, Michael Lengger, Moheimin Khan, Jonel Ortiz, David A. Najera-Flores, Robert J. Kuether, Paul R. Miles, Chao Xu, Huiyi Yang, Hassan Jalali, Javad Taghipour, Hamed Haddad Khodaparast, M. I. Friswell, Paolo Tiso, Ahmed Amr Morsy, Arati Bhattu, Svenja Hermann, H. Nevzat Özgüven, Nidhal Jamia, Florian Müller, and Maren Scheel
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- 2023
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3. Design and Testing of a Co-Rotating Vibration Excitation System.
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Angelos Filippatos, Tino Wollmann, Minh Nguyen 0005, Pawel Kostka, Martin Dannemann, Albert Langkamp, Loic Salles, and Maik Gude
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- 2019
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4. Higher-Order Invariant Manifold Parametrisation of Geometrically Nonlinear Structures Modelled with Large Finite Element Models
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Alessandra Vizzaccaro, Andrea Opreni, Loic Salles, Attilio Frangi, and Cyril Touzé
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- 2022
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5. Comparison of Reduction Methods for Finite Element Geometrically Nonlinear Beam Structures
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Loic Salles, Olivier Thomas, Yichang Shen, Alessandra Vizzaccaro, Nassim Kesmia, Ting Yu, Cyril Touzé, Institut des Sciences de la mécanique et Applications industrielles (IMSIA - UMR 9219), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay-EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), Imperial College London, Laboratoire d’Ingénierie des Systèmes Physiques et Numériques (LISPEN), Arts et Métiers Sciences et Technologies, HESAM Université (HESAM)-HESAM Université (HESAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-EDF R&D (EDF R&D), and HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)
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Technology ,reduced-order model ,SPECTRAL SUBMANIFOLDS ,DIMENSION REDUCTION ,02 engineering and technology ,Mechanics ,COMPUTATION ,Curvature ,01 natural sciences ,CIRCULAR CYLINDRICAL-SHELLS ,Modal derivatives ,Implicit condensation and expansion ,Mécanique: Vibrations [Sciences de l'ingénieur] ,Engineering ,Quadratic equation ,Geometric nonlinearity ,0203 mechanical engineering ,SYSTEMS ,SLOW-FAST DECOMPOSITION ,0103 physical sciences ,Mécanique: Mécanique des structures [Sciences de l'ingénieur] ,Invariant (mathematics) ,010301 acoustics ,direct normal form ,Physics ,REDUCED-ORDER MODELS ,Science & Technology ,Mathematical analysis ,[SPI.MECA.VIBR]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Vibrations [physics.class-ph] ,implicit condensation and expansion ,geometric nonlinearity ,modal derivatives ,[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,Linear subspace ,Finite element method ,lcsh:QC1-999 ,RESPONSE PREDICTION ,Engineering, Mechanical ,Reduced-order model ,Nonlinear system ,020303 mechanical engineering & transports ,model order reduction ,[SPI.MECA.STRU]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph] ,LARGE-AMPLITUDE VIBRATIONS ,SPHERICAL-SHELLS ,[SPI.GCIV.DV]Engineering Sciences [physics]/Civil Engineering/Dynamique, vibrations ,Reduction (mathematics) ,Beam (structure) ,lcsh:Physics - Abstract
The aim of this contribution is to present numerical comparisons of model-order reduction methods for geometrically nonlinear structures in the general framework of finite element (FE) procedures. Three different methods are compared: the implicit condensation and expansion (ICE), the quadratic manifold computed from modal derivatives (MD), and the direct normal form (DNF) procedure, the latter expressing the reduced dynamics in an invariant-based span of the phase space. The methods are first presented in order to underline their common points and differences, highlighting in particular that ICE and MD use reduction subspaces that are not invariant. A simple analytical example is then used in order to analyze how the different treatments of quadratic nonlinearities by the three methods can affect the predictions. Finally, three beam examples are used to emphasize the ability of the methods to handle curvature (on a curved beam), 1:1 internal resonance (on a clamped-clamped beam with two polarizations), and inertia nonlinearity (on a cantilever beam).
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- 2021
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6. Optimization of a Turbomachinery Blade With Regards to Tip-Rub Events
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Marin de Cherisey, Loic Salles, Ludovic Renson, Alessandra Vizzaccaro, and Chian Wong
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Tip-rub events, also called blade-casing interactions, are problematic structural phenomena that can lead to complete engine failure. They mainly occur in compressors when a blade tip touches the casing and starts vibrating. If one of the blade natural modes is excited by an engine order, this can lead to an uncontrolled resonance. Therefore, the understanding and the consideration of these interactions is crucial to the development of safe aircraft engines. Various numerical models and dynamic simulators have been developed, including the in-house one, jm62. It implements a stick-slip model and considers a potential liner and casing wear. Even if it gives precise results, it is computationally expensive and needs a significant amount of post-processing. It is therefore not really adapted to early design stages or quick automated processes (parametric study or optimization). An automated workflow using SALOME-MECA and its sub-modules had been developed and permits to perform simple and fast parametric studies and shape optimizations. The proposed tool has been used to study the influence of the twist, lean, sweep and tip thickness-to-chord ratio on a modified version of a NASA Rotor 37 blade. The risk of high-level vibration of a blade due to tip-rub events is assessed using the concept of clearance consumption. The clearance consumption is defined as the component of the linear or nonlinear mode shape that defines the distance between the tip of the blade and the casing. From the reference blade and the parametric study results, an optimized candidate was generated using the clearance consumption as the objective function to minimize This process resulted in a geometry with a lower twist angle and a significant forward sweep. Two scenario of tip rub events have been performed on the optimised blades. The testing relies on the in-house time integration software jm62. The candidate has showed a 85% reduction in the amplitude of the vibratory response for the first scenario, demonstrating that the clearance consumption can be used to perform successful shape optimizations for tip-rubbing.
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- 2022
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7. Topology optimisation of friction under-platform dampers using moving morphable components and the efficient global optimization algorithm
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Enora Denimal, Ludovic Renson, Chian Wong, Loic Salles, Royal Academy of Engineering, Royal Academy Of Engineering, Statistical Inference for Structural Health Monitoring (I4S), Inria Rennes – Bretagne Atlantique, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Département Composants et Systèmes (COSYS), Université Gustave Eiffel-Université Gustave Eiffel, Department of Mechanical Engineering [Imperial College London], Imperial College London, Rolls Royce PLC, and Skolkovo Institute of Science and Technology [Moscow] (Skoltech)
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Technology ,Control and Optimization ,Engineering, Multidisciplinary ,Mechanics ,09 Engineering ,Engineering ,Efficient global optimisation ,UNDERPLATFORM DAMPERS ,TURBINE-BLADES ,Moving morphable components ,LEVEL-SET METHOD ,01 Mathematical Sciences ,Science & Technology ,STRUCTURAL TOPOLOGY ,MAXIMIZATION ,Topology optimisation ,[SPI.MECA.VIBR]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Vibrations [physics.class-ph] ,Friction damping ,Design Practice & Management ,Computer Graphics and Computer-Aided Design ,Nonlinear vibrations ,Computer Science Applications ,Kriging ,Control and Systems Engineering ,Computer Science ,HARMONIC-BALANCE METHOD ,SIMULATION ,Computer Science, Interdisciplinary Applications ,Software - Abstract
International audience; Underplatform dampers (UPDs) are traditionally used in aircraft engines to reduce the risk of high cycle fatigue. By introducing friction in the system, vibrations at resonance are damped. However, UDPs are also the source of nonlinear behaviours making the analysis and the design of such components complex. The shape of such friction dampers has a substantial impact on the damping performances, topology optimisation is seldomly utilised-particularly for nonlinear structures. In the present work, we present a numerical approach to optimise the topology of friction dampers in order to minimise the vibration amplitude at a resonance peak. The proposed approach is based on the Moving Morphable Components framework to parametrise the damper topology, and the Efficient Global Optimisation algorithm is employed for the optimisation. The results demonstrate the relevance of such an approach for the optimisation of nonlinear vibrations in the presence of friction. New efficient damper geometries are identified in a few iterations of the algorithm, illustrating the efficiency of the approach. Results show that the most efficient geometry divides the vibration amplitude at resonance by 3, corresponds to a lower mass (80%) and a smaller frequency shift compared to the non-optimised case. More generally, the different geometries are analysed and tools for clustering are proposed. Different clusters are identified and compared. Thus, more general conclusions can be obtained. More specifically, the most efficient geometries correspond to geometries that reduce the mass of the damper and increase the length of the contact surface. Physically, it corresponds to a reduction of the initial normal contact pressure, which implies that the contact points enter stick/slip earlier, bringing more damping. The results show how topology optimisation can be employed for nonlinear vibrations to identify efficient layouts for components.
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- 2022
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8. Topological optimisation and 3D printing of a Bladed disc
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Vincent Barreau, Enora Denimal, Loic Salles, Denimal, Enora, Department of Mechanical Engineering [Imperial College London], Imperial College London, Statistical Inference for Structural Health Monitoring (I4S), Inria Rennes – Bretagne Atlantique, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Département Composants et Systèmes (COSYS), and Université Gustave Eiffel-Université Gustave Eiffel
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BLADED DISC ,[SPI.MECA.VIBR]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Vibrations [physics.class-ph] ,[SPI.MECA.VIBR] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Vibrations [physics.class-ph] - Abstract
In turbomachinery, components are pushed to their limits to meet more stringent specifications in order to increase their performances. In this context, structural topology optimisation is a promising technology as it improves substantially the mechanical properties while drastically reducing the mass. With the coming of additive manufacturing, optimised geometry can be manufactured making this technology even more attractive. The aim of this work is to investigate the potential of topology optimisation to optimise a full bladed disc to improve its dynamic performances in terms of mass, stress and modal coincidences. The topology of a 3D-Finite Element Model of an academic bladed disc is optimised in this work and experimental validation is expected. So first, the disc is designed to fit in the test-rig and the mechanical integrity of the 3D-printed disc is experimentally verified. Second, the topology of the blades is optimised. Based on a trial-and-error process, the appropriate topology optimisation problem properties for vibration optimisation are identified. Thus, adding a static force at the blade tip forces a better material distribution over the domain and increases the blade stiffness. To minimise the number of coincidences, a numerical strategy based on iterative topology optimisation simulations is proposed to identify the correct set of frequential constraints. Final results show that the mass of the blade is reduced up to 32% and the number of frequential coincidences is reduced from 11 to 4. Final geometries are 3D-printed and mounted on the disc.
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- 2022
9. Effects of the Geometry of Friction Interfaces on the Nonlinear Dynamics of Jointed Structure
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Christoph W. Schwingshackl, Loic Salles, Jie Yuan, Kerschen, Gaetan, Brake, Matthew R.W., and Renson, Ludovic
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Vibration ,Nonlinear system ,Work (thermodynamics) ,Materials science ,Mechanical joint ,Geometry ,Static pressure ,TJ ,Dissipation ,Solver ,Boundary element method - Abstract
Friction interfaces are commonly used in large-scale engineering systems for mechanical joints. They are known to significantly shift the resonance frequencies of the assembled structures due to softening effects and to reduce the vibration amplitude due to frictional energy dissipation between substructural components. It is also widely recognized that the geometrical characteristics of interface geometry have a significant impact on the nonlinear dynamical response of assembled systems. However, the full FE modeling approaches including these geometrical characteristics are extremely expensive. In this work, the influence of geometry of friction interfaces is investigated by using a multi-scale approach. It consists in integrating a semi-analytical contact solver into a high-fidelity nonlinear vibration solver. A highly efficient semi-analytical solver based on the boundary element method is used to obtain the pressure and gap distribution from the contact interface with different geometrical characteristics. The static pressure and gap distribution are then used as input for a nonlinear vibration solver to evaluate nonlinear vibrations of the whole assembled structure. The effectiveness of the methodology is shown on a realistic “Dogbone” test rig, which was designed to assess the effects of blade root geometries in a fan blade disk system. The friction joints with different interface profiles are then investigated. The obtained results show that the effects of the surface geometrical characteristics can have a significant impact on the damping and resonant frequency behavior of the whole assembly.
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- 2022
10. Influence of mesoscale friction interface geometry on the nonlinear dynamic response of large assembled structures
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Jie Yuan, Loic Salles, David Nowell, and Christoph Schwingshackl
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Control and Systems Engineering ,Mechanical Engineering ,Signal Processing ,Aerospace Engineering ,Computer Science Applications ,Civil and Structural Engineering - Abstract
Friction interfaces are unavoidable components of large engineering assemblies since they enable complex designs, ensure alignment, and enable the transfer of mechanical loads between the components. Unfortunately, they are also a major source of nonlinearities and uncertainty in the static and dynamic response of the assembly, due to the complex frictional physics occurring at the interface. One major contributor to the nonlinear dynamic behavior of the interface is the mesoscale geometry of a friction interface. Currently, the effects of the interface geometry on the nonlinear dynamic response is often ignored in the analysis due to the high computational cost of discretizing the interface to such fine levels for classical finite element analysis. In this paper, the influence of mesoscale frictional interface geometries on the nonlinear dynamic response is investigated through an efficient multi-scale modeling framework based on the boundary element method. A highly integrated refined contact analysis, static analysis, and nonlinear modal analysis approach are presented to solve a multi-scale problem where mesoscale frictional interfaces are embedded into the macroscale finite element model. The efficiency of the framework is demonstrated and validated against an existing dovetail dogbone test rig. Finally, the effects of different mesoscale interface geometries such as surface waviness and edge radius, are numerically investigated, further highlighting the influence of mesoscale interface geometries on the nonlinear dynamics of jointed structures and opening a new research direction for the design of friction interfaces in friction involved mechanical systems.
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- 2023
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11. Effect of Manufacturing Tolerance in Flow Past a Compressor Blade
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Mehdi Vahdati, Venkatesh Suriyanarayanan, Quentin Rendu, and Loic Salles
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Overall pressure ratio ,Materials science ,business.industry ,Rotor (electric) ,Mechanical Engineering ,Flow (psychology) ,Mechanics ,Solver ,Computational fluid dynamics ,law.invention ,Physics::Fluid Dynamics ,Zigzag ,law ,Compressor blade ,Annulus (firestop) ,Reynolds-averaged Navier–Stokes equations ,business ,Gas compressor ,Transonic - Abstract
This paper presents the effect of manufacturing tolerance on performance and stability boundaries of a transonic fan using a Reynolds-averaged Navier–Stokes simulation. The effects of tip gap and stagger angle variations were analyzed through a series of single passage and double passage simulation; based on which an optimal arrangement was proposed for random tip gap and random stagger angle variation for a whole annulus rotor. All simulations were carried out using NASA rotor 67 as a test case and AU3D as an in-house computational fluid dynamics solver. Results illustrate that the stagger angle variation mainly affects efficiency and its circumferential variation must be as smooth as possible. Furthermore, the tip gap variation affects the stability boundary as well as performance and its optimal configuration mandates a zigzag arrangement of blades around the annulus, i.e., larger tip gap between two smaller ones.
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- 2021
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12. The Data-Driven Surrogate Model-Based Dynamic Design of Aeroengine Fan Systems
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Jie Yuan, Loic Salles, Zi-Qiang Lang, Yunpeng Zhu, Christoph W. Schwingshackl, Visakan Kadirkamanathan, and Engineering & Physical Science Research Council (E
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Technology ,Frequency response ,0209 industrial biotechnology ,Design ,Energy Engineering and Power Technology ,Aerospace Engineering ,02 engineering and technology ,NONLINEAR-SYSTEMS ,PREDICT ,0901 Aerospace Engineering ,Data driven ,Engineering ,Surrogate model ,020901 industrial engineering & automation ,0203 mechanical engineering ,Control theory ,FREQUENCY-RESPONSE ,ALGORITHM ,Fan blade system ,Dry film lubricant coating ,LATIN HYPERCUBE ,Structured systems analysis and design method ,Contact friction ,Science & Technology ,Energy ,Mechanical Engineering ,Dissipation ,Dovetail joint ,Engineering, Mechanical ,Vibration ,Nonlinear system ,020303 mechanical engineering & transports ,Fuel Technology ,Autoregressive model ,Nuclear Energy and Engineering ,UNIFORM DESIGN ,TJ ,0913 Mechanical Engineering - Abstract
High cycle fatigue failures of fan blade systems due to vibrational loads are of great concern in the design of aero engines, where energy dissipation by the relative frictional motion in the dovetail joints provides the main damping to mitigate the vibrations. The performance of such a frictional damping can be enhanced by suitable coatings. However, the analysis and design of coated joint roots of gas turbine fan blades are computationally expensive due to strong contact friction nonlinearities and also complex physics involved in the dovetail. In this study, a data driven surrogate model, known as the Nonlinear in Parameter AutoRegressive with eXegenous input (NP-ARX) model, is introduced to circumvent the difficulties in the analysis and design of fan systems. The NP-ARX model is a linear input-output model, where the model coefficients are nonlinear functions of the design parameters of interest, such that the Frequency Response Function (FRF) can be directly obtained and used in the system analysis and design. A simplified fan bladed disc system is considered as the test case. The results show that by using the data driven surrogate model, an efficient and accurate design of aero-engine fan systems can be achieved. The approach is expected to be extended to solve the analysis and design problems of many other complex systems.
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- 2021
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13. Stress and Modal Analysis of a Rotating Blade and the Effects of Nonlocality
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Quentin Rendu, John P. Dear, Loic Salles, J. Yuan, A. V. Cherednichenko, and Mertol Tüfekci
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Stress (mechanics) ,Physics ,Quantum nonlocality ,Blade (geometry) ,Modal analysis ,Mechanics ,Boundary value problem ,Elasticity (physics) ,Integral equation ,Finite element method - Abstract
This study focuses on the quasi-static stress and modal analyses of a rotor blade by using classical and nonlocal elasticity approaches. The finite element method with an additional numerical integration process is used to evaluate the integral equation of nonlocal contionuum mechanics. The blade is assumed to be made of a linear elastic material of weak nonlocal characteristic. Such materials can be composites, metallic foams, nanophased alloys etc. A full-scale fan blade model is chosen as the test case to represent the rotor blade for a modern high bypass ratio turbofan engine. The boundary conditions and loads are chosen based on the steady-state cruising operating conditions of such blades. The nonlocal stresses are calculated by processing the calculated local stresses. To calculate the nonlocal stresses, the integral form of nonlocal elasticity is employed in the discretised domain. The results of the two cases are compared and discussed.
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- 2021
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14. Parallel Harmonic Balance Method for Analysis of Nonlinear Dynamical Systems
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Loic Salles, J. Blahoš, F. El Haddad, and Alessandra Vizzaccaro
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Physics ,01 natural sciences ,Jet engine ,law.invention ,Vibration ,Nonlinear dynamical systems ,010101 applied mathematics ,Harmonic balance ,Control theory ,law ,Computer software ,Solid mechanics ,0103 physical sciences ,0101 mathematics ,010301 acoustics - Abstract
Controlling vibration in jet engine remains one of the biggest challenges in aircraft engine design and conception. Methods dealing with vibration modelling usually rely on reduced order modelling techniques. This paper aims to provide a high fidelity method to solve vibration problems. It presents a parallel harmonic balance method applied to a full size problem. In order to be computationally efficient, a parallel harmonic balance method is used for the first time in solid mechanics. First, the parallel implementation of harmonic balance method is described in detail. The algorithm is designed to minimize communication between cores. Then, the software is tested for both beam and blade geometries. Finally, a scalability study shows promising acceleration when increasing the number of cores.
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- 2021
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15. Effect of Geometric Uncertainty on a One Stage Transonic Compressor of an Industrial Gas Turbine
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Loic Salles, K. Suzuki, S. Venkatesh, Mehdi Vahdati, and Quentin Rendu
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Transonic compressor ,Annulus (firestop) ,One stage ,Industrial gas ,Mechanics ,Turbine ,Gas compressor ,Geology - Abstract
The geometrical uncertainties can result in flow asymmetry around the annulus of compressor which in turn can detrimentally affect on the compressor stability and performance. Typically these uncertainties arise as a consequence of in-service degradation and/or manufacturing tolerance, both of which have been dealt with in this paper. The paper deals with effects of leading edge damage and tip gap on rotor blades. It was found that the chord-wise damage is more critical than radial damage. It was found that a zigzag pattern of arranging the damaged rotor blades (i.e. most damaged blades between two least damaged blades) would give the best possible performance and stability when performing maintenance and overhauling while a sinusoidal pattern of arrangement had the worst performance and stability. This behaviour of zigzag arrangement of random damaged blades is consonant with the behaviour of zigzag arrangement in random tip gaps. It is also shown in this work that the level of damage has a bigger impact on the compressor performance and stability than the number of damaged blades.
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- 2021
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16. Nonlinear modeling of structures with bolted joints: A comparison of two approaches based on a time-domain and frequency-domain solver
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Luca Pesaresi, J. Armand, Christoph W. Schwingshackl, Loic Salles, Robert M. Lacayo, Daniel Fochler, Matthew S. Allen, Johann Groß, Matthew R. W. Brake, University of Wisconsin-Madison [Madison], Imperial College London, Universität Stuttgart [Stuttgart], Laboratoire de Tribologie et Dynamique des Systèmes ( LTDS ), École Centrale de Lyon ( ECL ), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État ( ENTPE ) -Ecole Nationale d'Ingénieurs de Saint Etienne-Centre National de la Recherche Scientifique ( CNRS ), Department of Mechanical Engineering [Imperial College London], and Rice University [Houston]
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0209 industrial biotechnology ,[ SPI.MECA ] Engineering Sciences [physics]/Mechanics [physics.med-ph] ,Computer science ,friction ,Aerospace Engineering ,02 engineering and technology ,0915 Interdisciplinary Engineering ,01 natural sciences ,0905 Civil Engineering ,Harmonic balance ,020901 industrial engineering & automation ,0103 physical sciences ,Time domain ,010301 acoustics ,Civil and Structural Engineering ,damping ,business.industry ,Mechanical Engineering ,model updating ,Acoustics ,harmonic balance ,Structural engineering ,Solver ,modal analysis ,Computer Science Applications ,Nonlinear system ,nonlinear vibration ,Control and Systems Engineering ,Frequency domain ,Mechanical joint ,Bolted joint ,Signal Processing ,business ,Beam (structure) ,0913 Mechanical Engineering - Abstract
International audience; Motivated by the current demands in high-performance structural analysis, and by a need to better model systems with localized nonlinearities, analysts have developed a number of different approaches for modeling and simulating the dynamics of a bolted-joint structure. However, it is still unclear which approach might be most effective for a given system or set of conditions. To better grasp their similarities and differences, this paper presents a numerical benchmark that assesses how well two diametrically differing joint modeling approaches – a time-domain whole-joint approach and a frequency-domain node-to-node approach – predict and simulate a mechanical joint. These approaches were applied to model the Brake-Reuß beam, a prismatic structure comprised of two beams with a bolted joint interface. The two approaches were validated first by updating the models to reproduce the nonlinear response for the first bending mode of an experimental Brake-Reuß beam. Afterwards, the tuned models were evaluated on their ability to predict the nonlinearity in the dynamic response for the second and third bending modes. The results show that the two joint modeling approaches perform about equally as well in simulating the Brake-Reuß beam. In addition, the exposition highlights improvements that were made in each method during the course of this work and reveal further challenges in advancing the state-of-the-art.
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- 2019
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17. Comparison of different methodologies for the computation of damped nonlinear normal modes and resonance prediction of systems with non-conservative nonlinearities
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Alessandra Vizzaccaro, Loic Salles, Jie Yuan, and Yekai Sun
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Work (thermodynamics) ,Technology ,Computer science ,Computation ,MODAL-ANALYSIS ,PERIODIC-SOLUTION ,Aerospace Engineering ,Ocean Engineering ,02 engineering and technology ,Mechanics ,01 natural sciences ,09 Engineering ,Engineering ,0203 mechanical engineering ,Normal mode ,0103 physical sciences ,Applied mathematics ,Nonlinear vibration ,Electrical and Electronic Engineering ,INTEGRALLY BLADED DISKS ,010301 acoustics ,01 Mathematical Sciences ,Nonlinear modal analysis ,Science & Technology ,FORCED RESPONSES ,Non conservative ,Applied Mathematics ,Mechanical Engineering ,Damped nonlinear normal modes ,Resonance ,FRICTION ,Acoustics ,Periodic function ,Engineering, Mechanical ,Nonlinear system ,020303 mechanical engineering & transports ,Modal ,Control and Systems Engineering ,Nonlinear damping ,TJ - Abstract
The nonlinear modes of a non-conservative nonlinear system are sometimes referred to as damped nonlinear normal modes (dNNMs). Because of the non-conservative characteristics, the dNNMs are no longer periodic. To compute non-periodic dNNMs using classic methods for periodic problems, two concepts have been developed in the last two decades: complex nonlinear mode (CNM) and extended periodic motion concept (EPMC). A critical assessment of these two concepts applied to different types of non-conservative nonlinearities and industrial full-scale structures has not been thoroughly investigated yet. Furthermore, there exist two emerging techniques which aim at predicting the resonant solutions of a nonlinear forced response using the dNNMs: extended energy balance method (E-EBM) and nonlinear modal synthesis (NMS). A detailed assessment between these two techniques has been rarely attempted in the literature. Therefore, in this work, a comprehensive comparison between CNM and EPMC is provided through two illustrative systems and one engineering application. The EPMC with an alternative damping assumption is also derived and compared with the original EPMC and CNM. The advantages and limitations of the CNM and EPMC are critically discussed. In addition, the resonant solutions are predicted based on the dNNMs using both E-EBM and NMS. The accuracies of the predicted resonances are also discussed in detail.
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- 2021
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18. Topological Optimisation of Friction Dampers for Nonlinear Resonances Mitigation
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Enora Denimal, Ludovic Renson, Loic Salles, Department of Mechanical Engineering [Imperial College London], and Imperial College London
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[SPI]Engineering Sciences [physics] ,[SPI.MECA.VIBR]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Vibrations [physics.class-ph] ,topological optimisation ,[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,friction damping ,efficient global optimisation ,moving morphable component - Abstract
International audience; Friction dampers are commonly used to reduce the vibration amplitude of aircraft turbine blades. However, the shape of such friction dampers can affect significantly damping characteristics and the overall nonlinear dynamic behaviour of the structure. The present work exploits topological optimization to identify damper geometries that minimize response amplitude. The (near-)maximum responses are efficiently computed by solving the harmonic balance equations and a phase quadrature condition. Moving Morphable Components (MMC) are used to describe the damper geometry and an Efficient Global Optimization (EGO) algorithm is used for the optimization.
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- 2021
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19. Propagation of friction parameter uncertainties in the nonlinear dynamic response of turbine blades with underplatform dampers
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Loic Salles, Shubham Bhatnagar, Jie Yuan, Alfredo Fantetti, Christoph W. Schwingshackl, Luca Pesaresi, Enora Denimal, Department of Mechanical Engineering [Imperial College London], Imperial College London, and University of Strathclyde [Glasgow]
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0209 industrial biotechnology ,Turbine blade ,Aerospace Engineering ,02 engineering and technology ,0915 Interdisciplinary Engineering ,01 natural sciences ,0905 Civil Engineering ,Damper ,law.invention ,[SPI]Engineering Sciences [physics] ,020901 industrial engineering & automation ,law ,0103 physical sciences ,Uncertainty quantification ,010301 acoustics ,ComputingMilieux_MISCELLANEOUS ,Civil and Structural Engineering ,Polynomial chaos ,business.industry ,Mechanical Engineering ,[SPI.MECA.VIBR]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Vibrations [physics.class-ph] ,Sobol sequence ,Structural engineering ,Acoustics ,Dissipation ,[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,Computer Science Applications ,Vibration ,Nonlinear system ,Control and Systems Engineering ,Signal Processing ,TJ ,business ,0913 Mechanical Engineering - Abstract
Underplatform dampers are widely used in turbomachinery to mitigate structural vibrations by means of friction dissipation at the interfaces. The modelling of such friction dissipation is challenging because of the high variability observed in experimental measurements of contact parameters. Although this variability is not commonly accounted for in state-of-the-art numerical solvers, probabilistic approaches can be implemented to include it in dynamics simulations in order to significantly improve the estimation of the damper performance. The aim of this work is to obtain uncertainty bands in the dynamic response of turbine blades equipped with dampers by including the variability observed in interfacial contact parameters. This variability is experimentally quantified from a friction rig and used to generate uncertainty bands by combining a deterministic state-of-the-art numerical solver with stochastic Polynomial Chaos Expansion (PCE) models. The bands thus obtained are validated against experimental data from an underplatform damper test rig. In addition, the PCEs are also employed to perform a variance-based global sensitivity analysis to quantify the influence of contact parameters on the variation in the nonlinear dynamic response via Sobol indices. The analysis highlights that the influence of each contact parameter in vibration amplitude strongly varies over the frequency range, and that Sobol indices can be effectively used to analyse uncertainties associated to structures with friction interfaces providing valuable insights into the physics of such complex nonlinear systems.
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- 2021
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20. On the Efficiency of a Conical Under-Platform Damper for Turbines
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Loic Salles, Luca Pesaresi, Chian Wong, Enora Denimal, Department of Mechanical Engineering [Imperial College London], Imperial College London, Rolls Royce PLC, Innovate UK, and Engineering & Physical Science Research Council (E
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Technology ,business.product_category ,Turbine blade ,020209 energy ,Energy Engineering and Power Technology ,Aerospace Engineering ,02 engineering and technology ,Kinematics ,0901 Aerospace Engineering ,law.invention ,Damper ,Physics::Fluid Dynamics ,Damping capacity ,Engineering ,law ,0202 electrical engineering, electronic engineering, information engineering ,ComputingMilieux_MISCELLANEOUS ,Slip (vehicle dynamics) ,Physics ,Science & Technology ,Energy ,business.industry ,Mechanical Engineering ,[SPI.MECA.VIBR]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Vibrations [physics.class-ph] ,Structural engineering ,Conical surface ,[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,Wedge (mechanical device) ,[SPI.MECA.STRU]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of the structures [physics.class-ph] ,Engineering, Mechanical ,Vibration ,Fuel Technology ,Nuclear Energy and Engineering ,[SPI.MECA.STRU]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph] ,business ,0913 Mechanical Engineering - Abstract
Underplatform dampers (UPDs) are commonly used in aircraft engines to limit the risk of high-cycle fatigue of turbine blades. The latter is located in a groove between two consecutive blades. The dry friction contact interface between the damper and the blades dissipates energy and so reduces the vibration amplitudes. Two common geometries of dampers are used nowadays, namely wedge and cylindrical dampers, but their efficiency is limited when the blades have an in-phase motion (or a motion close to it), since the damper tends to have a pure rolling motion. The objective of this study is to analyze a new damper geometry, based on a conical shape, which prevents from this pure rolling motion of the damper and ensures a high kinematic slip. The objective of this study is to demonstrate the damping efficiency of this geometry. Hence, in a first part, the kinematic slip is approximated with analytical considerations. Then, a nonlinear dynamic analysis is performed, and the damping efficiency of this new geometry is compared to the wedge and the cylindrical geometries. The results demonstrate that the conical damper has a high damping capacity and is more efficient and more robust than the two others.
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- 2021
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21. Topological Optimization of Under-Platform Dampers with Moving Morphable Components and Global Optimization Algorithm for Nonlinear Frequency Response
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F. El Haddad, Enora Denimal, Chian Wong, Loic Salles, Department of Mechanical Engineering [Imperial College London], Imperial College London, Rolls Royce PLC, Engineering & Physical Science Research Council (E, The authors thank Rolls-Royce plc and the EPSRC for the support under the Prosperity Partnership Grant 'Cornerstone: Mechanical Engineering Science to Enable Aero Propulsion Futures', Grant Ref: EP/R004951/1., Statistical Inference for Structural Health Monitoring (I4S), Inria Rennes – Bretagne Atlantique, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Département Composants et Systèmes (COSYS), and Université Gustave Eiffel-Université Gustave Eiffel
- Subjects
0209 industrial biotechnology ,Frequency response ,Technology ,Optimization problem ,Computer science ,020209 energy ,Energy Engineering and Power Technology ,Aerospace Engineering ,Topology (electrical circuits) ,02 engineering and technology ,0901 Aerospace Engineering ,Damper ,[SPI]Engineering Sciences [physics] ,020901 industrial engineering & automation ,Engineering ,0203 mechanical engineering ,Kriging ,Control theory ,0202 electrical engineering, electronic engineering, information engineering ,Limit (mathematics) ,ComputingMilieux_MISCELLANEOUS ,Science & Technology ,Energy ,Mechanical Engineering ,[SPI.MECA.VIBR]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Vibrations [physics.class-ph] ,[SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph] ,[SPI.MECA.STRU]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of the structures [physics.class-ph] ,Vibration ,Engineering, Mechanical ,Nonlinear system ,020303 mechanical engineering & transports ,Fuel Technology ,Nuclear Energy and Engineering ,[SPI.MECA.STRU]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph] ,0913 Mechanical Engineering - Abstract
To limit the risk of High Cycle Fatigue, underplatform dampers are traditionally used in aircraft engines to control the level of vibration. Many studies demonstrate the impact of the geometry of the damper on its efficiency, thus the consideration of topological optimization to find the best layout of the damper seems natural. Because of the nonlinear behaviour of the structure due to the friction contact interface, classical methods of topological optimization are not usable. The present study proposes to optimize the layout of an underplatform damper to reduce the level of nonlinear vibrations computed with the Multi-Harmonic Balance Method. The approach of topological optimization employed is based on the Moving Morphable Components framework together with the Kriging and the Efficient Global Optimization algorithm to solve the optimization problem. The results show that the level of vibration of the structure can be reduced of 30% and allow for the identification of different efficient geometries.
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- 2021
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22. Experimental observations of nonlinear vibration localization in a cyclic chain of weakly coupled nonlinear oscillators
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Filipe Fontanela, Aurélien Grolet, Loic Salles, Norbert Hoffmann, Alessandra Vizzaccaro, Antonio Papangelo, Björn Niedergesäß, and A. J. Sievers
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Physics ,Vibration localization ,Acoustics and Ultrasonics ,Mechanical Engineering ,Numerical analysis ,Nonlinear vibration ,Mathematical analysis ,Cyclic structure ,02 engineering and technology ,Condensed Matter Physics ,01 natural sciences ,Reduced order ,Vibration ,Harmonic balance ,Nonlinear system ,Nonlinear oscillators ,Clearance ,020303 mechanical engineering & transports ,0203 mechanical engineering ,Chain (algebraic topology) ,Mechanics of Materials ,0103 physical sciences ,010301 acoustics - Abstract
Experimental results on nonlinear vibration localization in a cyclic chain of weakly coupled oscillators with clearance nonlinearity are reported. Numerical modelling and analysis complements the experimental study. A reduced order model is derived and numerical analysis based on the harmonic balance method demonstrates the existence of multiple classes of stable spatially localized nonlinear vibration states. The experiments agree very well with the numerical results. The findings suggest that vibration localization due to fundamentally nonlinear effects may also arise in mechanical structures with relevance in engineering.
- Published
- 2021
23. Non-intrusive reduced order modelling for the dynamics of geometrically nonlinear flat structures using three-dimensional finite elements
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Loic Salles, Arthur Givois, Yichang Shen, Alessandra Vizzaccaro, Olivier Thomas, Jean-François Deü, Pierluigi Longobardi, Cyril Touzé, Imperial College London, Laboratoire d’Ingénierie des Systèmes Physiques et Numériques (LISPEN), Arts et Métiers Sciences et Technologies, HESAM Université (HESAM)-HESAM Université (HESAM), Institut des Sciences de la mécanique et Applications industrielles (IMSIA - UMR 9219), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay-EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), Conservatoire National des Arts et Métiers [CNAM] (CNAM), HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-EDF R&D (EDF R&D), and Laboratoire de Mécanique des Structures et des Systèmes Couplés (LMSSC)
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FOS: Computer and information sciences ,Technology ,geometric nonlinearities ,Computational Mechanics ,Degrees of freedom (statistics) ,02 engineering and technology ,0915 Interdisciplinary Engineering ,01 natural sciences ,Modal derivatives ,VIBRATIONS ,Nonlinear modes ,Computational Engineering, Finance, and Science (cs.CE) ,[SPI]Engineering Sciences [physics] ,0203 mechanical engineering ,Mécanique: Mécanique des structures [Sciences de l'ingénieur] ,Computer Science - Computational Engineering, Finance, and Science ,010301 acoustics ,Physics ,Applied Mathematics ,Mathematical analysis ,Stiffness ,Computational mathematics ,modal derivatives ,Finite element method ,Computational Mathematics ,020303 mechanical engineering & transports ,Computational Theory and Mathematics ,thickness modes ,Physical Sciences ,SPHERICAL-SHELLS ,Thickness modes ,medicine.symptom ,nonlinear modes ,BEHAVIOR ,0913 Mechanical Engineering ,Mathematics, Interdisciplinary Applications ,Reduced order modeling ,Structure (category theory) ,Ocean Engineering ,Context (language use) ,Mechanics ,COMPUTATION ,0905 Civil Engineering ,Modified STiffness Evaluation Procedure ,SYSTEMS ,0103 physical sciences ,medicine ,NORMAL-MODES ,Science & Technology ,IDENTIFICATION ,Mechanical Engineering ,REDUCTION METHOD ,three-dimensional effect ,[SPI.MECA.VIBR]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Vibrations [physics.class-ph] ,FRAMEWORK ,Nonlinear system ,Modal ,[SPI.MECA.STRU]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph] ,Three-dimensional effect ,Geometric nonlinearities ,TURBULENCE ,Mathematics ,reduced order modeling - Abstract
Non-intrusive methods have been used since two decades to derive reduced-order models for geometrically nonlinear structures, with a particular emphasis on the so-called STiffness Evaluation Procedure (STEP), relying on the static application of prescribed displacements in a finite-element context. We show that a particularly slow convergence of the modal expansion is observed when applying the method with 3D elements, because of nonlinear couplings occurring with very high frequency modes involving 3D thickness deformations. Focusing on the case of flat structures, we first show by computing all the modes of the structure that a converged solution can be exhibited by using either static condensation or normal form theory. We then show that static modal derivatives provide the same solution with fewer calculations. Finally, we propose a modified STEP, where the prescribed displacements are imposed solely on specific degrees of freedom of the structure, and show that this adjustment also provides efficiently a converged solution., Comment: 6 tables, 14 figures, 27 pages
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- 2020
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24. Parametric study and uncertainty quantification of the nonlinear modal properties of frictional dampers
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Yekai Sun, Loic Salles, Jie Yuan, Luca Pesaresi, and Enora Denimal
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business.industry ,Modal analysis ,Monte Carlo method ,General Engineering ,02 engineering and technology ,Structural engineering ,01 natural sciences ,7. Clean energy ,Damper ,Nonlinear system ,020303 mechanical engineering & transports ,Modal ,0203 mechanical engineering ,Latin hypercube sampling ,0103 physical sciences ,TJ ,Uncertainty quantification ,business ,010301 acoustics ,Mathematics ,Parametric statistics - Abstract
A numerical methodology is described to study the influence of the contact location and contact condition of friction damper in aircraft engines. A simplified beam model is used to represent the blade for the preliminary design stage. The frictional damper is numerically analyzed based on two parameters, contact angle and vertical position of the platform. The nonlinear modal analysis is used to investigate the nonlinear dynamic behavior and damping performances of the system. The harmonic balanced method with the continuation technique is used to compute the nonlinear modes for a large range of energy levels. By using such a modeling strategy, the modal damping ratio, resonant amplitude, and resonant frequency are directly and efficiently computed for a range of design parameters. Monte Carlo simulations together with Latin hypercube sampling is then used to assess the robustness of the frictional damper, whose contact parameters involve much uncertainties due to manufacturing tolerance and also wear effects. The influences of those two parameters are obtained, and the best performances of the frictional damper can be achieved when the contact angle is around 25 deg–30 deg. The vertical position of the platform is highly mode dependent, and other design considerations need to be accounted. The results have proved that the uncertainties that involved contact surfaces do not have significant effects on the performance of frictional damper.
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- 2020
25. Direct computation of nonlinear mapping via normal form for reduced-order models of finite element nonlinear structures
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Loic Salles, Jiří Blahoš, Cyril Touzé, Alessandra Vizzaccaro, Yichang Shen, Imperial College London, Institut des Sciences de la mécanique et Applications industrielles (IMSIA - UMR 9219), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay-EDF R&D (EDF R&D), and Touzé, Cyril
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DYNAMICS ,FOS: Computer and information sciences ,Technology ,Normal form ,Computational Mechanics ,General Physics and Astronomy ,010103 numerical & computational mathematics ,Reduced order modelling ,01 natural sciences ,09 Engineering ,Computational Engineering, Finance, and Science (cs.CE) ,[SPI]Engineering Sciences [physics] ,Engineering ,Computer Science - Computational Engineering, Finance, and Science ,Mathematics ,cs.CE ,Applied Mathematics ,Mathematical analysis ,Numerical Analysis (math.NA) ,Invariant (physics) ,Finite element method ,Computer Science Applications ,010101 applied mathematics ,Mechanics of Materials ,Physical Sciences ,A priori and a posteriori ,Normal coordinates ,[SPI.MECA.VIBR] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Vibrations [physics.class-ph] ,[SPI.MECA.STRU] Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph] ,Subspace topology ,Mathematics, Interdisciplinary Applications ,DECOMPOSITION ,math.NA ,[SPI] Engineering Sciences [physics] ,Invariant manifold ,[MATH.MATH-DS]Mathematics [math]/Dynamical Systems [math.DS] ,[MATH.MATH-DS] Mathematics [math]/Dynamical Systems [math.DS] ,Engineering, Multidisciplinary ,SPECTRAL SUBMANIFOLDS ,Mechanics ,CYLINDRICAL-SHELLS ,SYSTEMS ,NUMERICAL COMPUTATION ,FOS: Mathematics ,Mathematics - Numerical Analysis ,0101 mathematics ,MODAL DERIVATIVES ,cs.NA ,01 Mathematical Sciences ,Science & Technology ,Nonlinear mapping ,Mechanical Engineering ,[SPI.MECA.VIBR]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Vibrations [physics.class-ph] ,REDUCTION ,Nonlinear system ,[SPI.MECA.STRU]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph] ,Phase space ,Geometric nonlinearities ,LARGE-AMPLITUDE VIBRATIONS ,PERIODIC VIBRATION - Abstract
The direct computation of the third-order normal form for a geometrically nonlinear structure discretised with the finite element (FE) method, is detailed. The procedure allows to define a nonlinear mapping in order to derive accurate reduced-order models (ROM) relying on invariant manifold theory. The proposed reduction strategy is direct and simulation free, in the sense that it allows to pass from physical coordinates (FE nodes) to normal coordinates, describing the dynamics in an invariant-based span of the phase space. The number of master modes for the ROM is not a priori limited since a complete change of coordinate is proposed. The underlying theory ensures the quality of the predictions thanks to the invariance property of the reduced subspace, together with their curvatures in phase space that accounts for the nonresonant nonlinear couplings. The method is applied to a beam discretised with 3D elements and shows its ability in recovering internal resonance at high energy. Then a fan blade model is investigated and the correct prediction given by the ROMs are assessed and discussed. A method is proposed to approximate an aggregate value for the damping, that takes into account the damping coefficients of all the slave modes, and also using the Rayleigh damping model as input. Frequency-response curves for the beam and the blades are then exhibited, showing the accuracy of the proposed method., 34 pages, 10 figures, 2 tables, submitted to CMAME
- Published
- 2020
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26. Nonlinear Modal Analysis of Frictional Ring Damper for Compressor Blisk
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Jie Yuan, Enora Denimal, Yekai Sun, Loic Salles, Engineering & Physical Science Research Council (E, Department of Mechanical Engineering [Imperial College London], and Imperial College London
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Technology ,Materials science ,Mass reduction ,Modal analysis ,Energy Engineering and Power Technology ,Aerospace Engineering ,02 engineering and technology ,01 natural sciences ,0901 Aerospace Engineering ,Contact force ,Damper ,[SPI]Engineering Sciences [physics] ,Integrally closed ,Engineering ,0203 mechanical engineering ,0103 physical sciences ,010301 acoustics ,Ring (mathematics) ,Science & Technology ,Energy ,business.industry ,Mechanical Engineering ,Nonlinear modal analysis ,[SPI.MECA.VIBR]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Vibrations [physics.class-ph] ,Resonance ,Aerodynamics ,Structural engineering ,Finite element method ,[SPI.MECA.GEME]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanical engineering [physics.class-ph] ,Engineering, Mechanical ,020303 mechanical engineering & transports ,Fuel Technology ,Nuclear Energy and Engineering ,TJ ,business ,Gas compressor ,0913 Mechanical Engineering - Abstract
The use of integrally blisk is becoming popular because of the advantages in aerodynamic efficiency and mass reduction. However, in an integrally blisk, the lack of the contact interface leads to a low structural damping compared to an assembled bladed-disk. One emerging damping technique for the integrally blisk is based on the use of friction ring damper which exploits the contact interfaces at the underneath of the disk. In this paper, three different geometries of the ring dampers are investigated for damping enhancement of a blisk. A full-scale compressor blisk is considered as a case study where a node to node contact model is used to compute the contact forces. The dynamic behaviour of the blisk with the ring damper is investigated by using nonlinear modal analysis which allows a direct estimation of the damping generated by the friction interface. The damping performance for the different ring dampers are evaluated and compared. It appears that the damping efficiency as well as the shift in the resonant frequency for the different geometries are highly related to the nodal diameter and contact pressure/gap distributed within contact interface. The geometry of the ring damper has significant impact on the damping performance.
- Published
- 2020
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27. On an improved adaptive reduced order model for the computation of steady state vibrations in large-scale non-conservative system with friction joints
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Jie Yuan, Loic Salles, Chian Wong, Christoph W. Schwingshackl, and Engineering & Physical Science Research Council (E
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DYNAMICS ,Technology ,Computer science ,Computation ,Aerospace Engineering ,Ocean Engineering ,SUBSTRUCTURES ,02 engineering and technology ,Mechanics ,01 natural sciences ,Error estimator ,PARAMETERS ,09 Engineering ,High fidelity ,Engineering ,0203 mechanical engineering ,Control theory ,0103 physical sciences ,Electrical and Electronic Engineering ,010301 acoustics ,01 Mathematical Sciences ,Contact friction ,Science & Technology ,Applied Mathematics ,Mechanical Engineering ,Estimator ,Acoustics ,Dovetail joint ,Nonlinear vibrations ,Vibration ,Engineering, Mechanical ,Reduced-order model ,Nonlinear system ,REDUCTION ,020303 mechanical engineering & transports ,Transmission (telecommunications) ,Control and Systems Engineering ,Mechanical joint ,Online adaptivity ,Large-scale assembly ,TJ - Abstract
Joints are commonly used in many large-scale engineering systems to ease assembly, and ensure structural integrity and effective load transmission. Most joints are designed around friction interfaces, which can transmit large static forces, but tend to introduce stick-slip transition during vibrations, leading to a nonlinear dynamic system. Tools for the complex numerical prediction of such nonlinear systems are available today, but their use for large-scale applications is regularly prevented by high computational cost. To address this issue, a novel adaptive reduced-order model (ROM) has recently been developed, significantly decreasing the computational time for such high fidelity simulations. Although highly effective, significant improvements to the proposed approach is presented and demonstrated in this paper, further increasing the efficiency of the ROM. An energy-based error estimator was developed and integrated into the nonlinear spectral analysis, leading to a significantly higher computational speed by removing insignificant static modes from the stuck contact nodes in the original reduced basis, and improving the computational accuracy by eliminating numerical noise. The effectiveness of the new approach was shown on an industrial-scale fan blades system with a dovetail joints, showing that the improved adaptive method can be 2–3 times more computationally efficient than the original adaptive method especially at high excitation levels but also effectively improve the accuracy of the original method.
- Published
- 2020
28. An extended energy balance method for resonance prediction in forced response of systems with non-conservative nonlinearities using damped nonlinear normal mode
- Author
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Loic Salles, Jie Yuan, Yekai Sun, Alessandra Vizzaccaro, and Engineering & Physical Science Research Council (E
- Subjects
Work (thermodynamics) ,Technology ,Energy balance ,Frictional contact ,Aerospace Engineering ,Ocean Engineering ,Mechanics ,COMPUTATION ,01 natural sciences ,09 Engineering ,Engineering ,Normal mode ,0103 physical sciences ,Force-amplitude responses ,Electrical and Electronic Engineering ,010301 acoustics ,01 Mathematical Sciences ,010302 applied physics ,Physics ,Science & Technology ,Applied Mathematics ,Mechanical Engineering ,Damped nonlinear normal modes ,Resonance ,STIFFNESS ,Acoustics ,Vibration ,Engineering, Mechanical ,Nonlinear system ,Control and Systems Engineering ,Dissipative system ,TJ ,Energy (signal processing) - Abstract
The dynamic analysis of systems with nonlinearities has become an important topic in many engineering fields. Apart from the forced response analyses, nonlinear modal analysis has been successfully extended to such non-conservative systems thanks to the definition of damped nonlinear normal modes. The energy balance method is a tool that permits to directly predict resonances for a conservative system with nonlinearities from its nonlinear modes. In this work, the energy balance method is extended to systems with non-conservative nonlinearities using the concept of the damped nonlinear normal mode and its application in a full-scale engineering structure. This extended method consists of a balance between the energy loss from the internal damping, the energy transferred from the external excitation and the energy exchanged with the non-conservative nonlinear force. The method assumes that the solution of the forced response at resonance bears resemblance to that of the damped nonlinear normal mode. A simplistic model and full-scale structure with dissipative nonlinearities and a simplistic model showing self-excited vibration are tested using the method. In each test case, resonances are predicted efficiently and the computed force–amplitude curves show a great agreement with the forced responses. In addition, the self-excited solutions and isolas in forced responses can be effectively detected and identified. The accuracy and limitations of the method have been critically discussed in this work.
- Published
- 2020
29. Nonlinear vibration localisation in a symmetric system of two coupled beams
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Loic Salles, Alessandra Vizzaccaro, Jeanne Auvray, Björn Niedergesäß, Aurélien Grolet, Norbert Hoffmann, Filipe Fontanela, Rolls-Royce Plc, Innovate UK, and Commission of the European Communities
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nlin.PS ,Technology ,Aerospace Engineering ,FOS: Physical sciences ,Ocean Engineering ,02 engineering and technology ,Pattern Formation and Solitons (nlin.PS) ,Mechanics ,01 natural sciences ,09 Engineering ,Piecewise linear function ,Symmetry breaking bifurcation ,Nonlinear oscillators ,Engineering ,0203 mechanical engineering ,0103 physical sciences ,medicine ,Electrical and Electronic Engineering ,010301 acoustics ,PERIODIC STRUCTURE ,01 Mathematical Sciences ,Physics ,Science & Technology ,Applied Mathematics ,Mechanical Engineering ,Nonlinear vibration ,Mathematical analysis ,Stiffness ,Vibration localisation ,Acoustics ,Nonlinear Sciences - Pattern Formation and Solitons ,Vibration ,Engineering, Mechanical ,Nonlinear system ,020303 mechanical engineering & transports ,Amplitude ,Control and Systems Engineering ,Clearance nonlinearity ,medicine.symptom ,MODE LOCALIZATION - Abstract
We report nonlinear vibration localisation in a system of two symmetric weakly coupled nonlinear oscillators. A two degree-of-freedom model with piecewise linear stiffness shows bifurcations to localised solutions. An experimental investigation employing two weakly coupled beams touching against stoppers for large vibration amplitudes confirms the nonlinear localisation., Comment: 14 pages, 11 figures
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- 2020
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30. Comparison of nonlinear mappings for reduced-order modelling of vibrating structures: normal form theory and quadratic manifold method with modal derivatives
- Author
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Loic Salles, Cyril Touzé, Alessandra Vizzaccaro, Institut des Sciences de la mécanique et Applications industrielles (IMSIA - UMR 9219), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-EDF R&D (EDF R&D), EDF (EDF)-EDF (EDF), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École Nationale Supérieure de Techniques Avancées (ENSTA Paris)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Saclay-EDF R&D (EDF R&D), Rolls-Royce Plc, and Engineering & Physical Science Research Council (E
- Subjects
FOS: Computer and information sciences ,Technology ,Normal form ,02 engineering and technology ,01 natural sciences ,Modal derivatives ,09 Engineering ,Computational Engineering, Finance, and Science (cs.CE) ,[SPI]Engineering Sciences [physics] ,Quadratic equation ,Engineering ,0203 mechanical engineering ,Normal mode ,[NLIN]Nonlinear Sciences [physics] ,Arch ,Computer Science - Computational Engineering, Finance, and Science ,010301 acoustics ,Mathematics ,cs.CE ,Reduced-order modelling ,Applied Mathematics ,Mathematical analysis ,Numerical Analysis (math.NA) ,Invariant (physics) ,Engineering, Mechanical ,020303 mechanical engineering & transports ,Quadratic manifold ,math.NA ,Aerospace Engineering ,Ocean Engineering ,SPECTRAL SUBMANIFOLDS ,Mechanics ,CIRCULAR CYLINDRICAL-SHELLS ,Continuation ,SYSTEMS ,NUMERICAL COMPUTATION ,0103 physical sciences ,FOS: Mathematics ,OSCILLATIONS ,Mathematics - Numerical Analysis ,Electrical and Electronic Engineering ,CONTINUATION ,cs.NA ,01 Mathematical Sciences ,NORMAL-MODES ,Science & Technology ,Mechanical Engineering ,[SPI.MECA.VIBR]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Vibrations [physics.class-ph] ,Acoustics ,Nonlinear system ,REDUCTION ,Modal ,Control and Systems Engineering ,PROPER ORTHOGONAL DECOMPOSITION ,[SPI.MECA.STRU]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph] ,Phase space ,LARGE-AMPLITUDE VIBRATIONS - Abstract
The objective of this contribution is to compare two methods proposed recently in order to build efficient reduced-order models for geometrically nonlinear structures. The first method relies on the normal form theory that allows one to obtain a nonlinear change of coordinates for expressing the reduced-order dynamics in an invariant-based span of the phase space. The second method is the modal derivative (MD) approach, and more specifically the quadratic manifold defined in order to derive a second-order nonlinear change of coordinates. Both methods share a common point of view, willing to introduce a nonlinear mapping to better define a reduced order model that could take more properly into account the nonlinear restoring forces. However the calculation methods are different and the quadratic manifold approach has not the invariance property embedded in its definition. Modal derivatives and static modal derivatives are investigated, and their distinctive features in the treatment of the quadratic nonlinearity is underlined. Assuming a slow/fast decomposition allows understanding how the three methods tend to share equivalent properties. While they give proper estimations for flat symmetric structures having a specific shape of nonlinearities and a clear slow/fast decomposition between flexural and in-plane modes, the treatment of the quadratic nonlinearity makes the predictions different in the case of curved structures such as arches and shells. In the more general case, normal form approach appears preferable since it allows correct predictions of a number of important nonlinear features, including for example the hardening/softening behaviour, whatever the relationships between slave and master coordinates are., 43 pages, 12 figures, published in Nonlinear Dynamics
- Published
- 2020
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31. On the effects of roughness on the nonlinear dynamics of a bolted joint: A multiscale analysis
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Loic Salles, D. Süß, J. Armand, Christoph W. Schwingshackl, and K. Willner
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Materials science ,Mechanical Engineering ,General Physics and Astronomy ,Stiffness ,02 engineering and technology ,Mechanics ,Surface finish ,Solver ,021001 nanoscience & nanotechnology ,0905 Civil Engineering ,Nonlinear system ,020303 mechanical engineering & transports ,Lap joint ,0203 mechanical engineering ,Mechanics of Materials ,Bolted joint ,medicine ,Surface roughness ,Mechanical Engineering & Transports ,General Materials Science ,medicine.symptom ,0210 nano-technology ,Joint (geology) ,0913 Mechanical Engineering - Abstract
Accurate prediction of the vibration response of friction joints is of great importance when estimating both the performance and the life of build-up structures. The contact conditions at the joint interface, including local normal load distribution and contact stiffness, play a critical role in the nonlinear dynamic response. These parameters strongly depend on the mating surfaces, where the surface roughness is well known to have a significant impact on the contact conditions in the static case. In contrast, its effects on the global and local nonlinear dynamic response of a build-up structure is not as well understood due to the complexity of the involved mechanisms. To obtain a better understanding of the dependence of the nonlinear dynamic response on surface roughness, a newly proposed multiscale approach has been developed. It links the surface roughness to the contact pressure and contact stiffness, and in combination with a multiharmonic balance solver, allows to compute the nonlinear dynamic response for different interface roughness. An application of the technique to a single bolted lap joint highlighted a strong impact of larger roughness values on the pressure distribution and local contact stiffness and in turn on the nonlinear dynamic response.
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- 2018
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32. An adaptive component mode synthesis method for dynamic analysis of jointed structure with contact friction interfaces
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Chian Wong, Loic Salles, Jie Yuan, Fadi El Haddad, Innovate UK, and Engineering & Physical Science Research Council (E
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Model order reduction ,Work (thermodynamics) ,Computer science ,Mechanical Engineering ,Interface (computing) ,Applied Mathematics ,Mode (statistics) ,09 Engineering ,Computer Science Applications ,Harmonic balance ,Control theory ,Modeling and Simulation ,Component (UML) ,General Materials Science ,TJ ,Reduction (mathematics) ,Slipping ,Civil and Structural Engineering - Abstract
Component model synthesis (CMS) has been widely used for model order reduction in dynamic analysis of jointed structures with localized non-linearities. The main drawback of these CMS methods is that their computational efficiency largely depends on the size of contact friction interfaces. This work proposes an adaptive reduction approach to improve these CMS based reduction methods in the application to the assembled structure with frictional interfaces. The main idea of this method is that, instead of retaining the whole frictional interface DOFs in the reduced model, only those DOFs in a slipping or separating condition are retained. This would significantly reduce the size of classical CMS based reduced models for dynamical analysis of jointed structure with micro-slip motion, leading to an impressive computational saving. This novel approach is based on a reformulated dynamic system that consists of a underlying linearised system and an adaptive internal variable to account the effects of non-linear contact friction force on the interface. The paper also describes the detailed implementation of the proposed approach with harmonic balance method for non-linear spectral analysis, where a new updating algorithm is put forward to enable the size of the reduced model can be automatically updated according to the contact condition of interface nodes. Two distinct FE joint models are used to validate the proposed method. It is demonstrated that the new approach can achieve a considerable computing speed-up comparing to the classic CMS approach while maintain the same accuracy.
- Published
- 2019
33. Radial Decomposition of Blade Vibration to Identify a Stall Flutter Source in a Transonic Fan
- Author
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Mehdi Vahdati, Loic Salles, and Quentin Rendu
- Subjects
Shock wave ,020301 aerospace & aeronautics ,Stall flutter ,Blade (geometry) ,Mechanical Engineering ,Computation ,02 engineering and technology ,Mechanics ,01 natural sciences ,010305 fluids & plasmas ,Physics::Fluid Dynamics ,Vibration ,0203 mechanical engineering ,0103 physical sciences ,Decomposition (computer science) ,Transonic ,Geology - Abstract
This paper investigates the three dimensionality of the unsteady flow responsible for stall flutter instability. Nonlinear unsteady Reynolds-averaged Navier–Stokes (RANS) computations are used to predict the aeroelastic behavior of a fan blade at part speed. Flutter is experienced by the blades at low mass flow for the first flap mode at nodal diameter 2. The maximal energy exchange is located near the tip of the blade, at 90% span. The modeshape is radially decomposed to investigate the main source of instability. This decomposition method is validated for the first time in 3D using a time-marching nonlinear solver. The source of stall flutter is finally found at 65% span where the local vibration induces an unstable oscillation of the shock-wave of large amplitude. This demonstrates that the radial migration of the pressure fluctuations must be taken into account to predict stall flutter.
- Published
- 2019
- Full Text
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34. On the use of ultrasound waves to monitor the local dynamics of friction joints
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Frederic Cegla, Luca Pesaresi, Loic Salles, Alfredo Fantetti, and Christoph W. Schwingshackl
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Technology ,Friction ,CONTACT ,SURFACE ,Computer science ,Materials Science ,SOLIDS ,Aerospace Engineering ,Mechanical engineering ,Materials Science, Multidisciplinary ,02 engineering and technology ,Materials Science, Characterization & Testing ,PRESSURE ,Mechanics ,0915 Interdisciplinary Engineering ,01 natural sciences ,BOLTED JOINTS ,0905 Civil Engineering ,Hysteresis loops ,Ultrasounds ,0203 mechanical engineering ,Contact stiffness ,0103 physical sciences ,medicine ,Mechanical Engineering & Transports ,Dynamical friction ,010301 acoustics ,Joint (geology) ,HYSTERESIS ,Science & Technology ,Mechanical Engineering ,AREA ,Stiffness ,STIFFNESS ,Nonlinear system ,020303 mechanical engineering & transports ,WEAR ,Mechanics of Materials ,Bolted joint ,Solid mechanics ,Reflection (physics) ,Harmonic ,medicine.symptom ,Microslip ,BEHAVIOR ,0913 Mechanical Engineering - Abstract
Friction joints are one of the fundamental means used for the assembly of structural components in engineering applications. The structural dynamics of these components becomes nonlinear, due to the nonlinear nature of the forces arising at the contact interface characterised by stick-slip phenomena and separation. Advanced numerical models have been proposed in the last decades which have shown some promising capabilities in capturing these local nonlinearities. However, despite the research efforts in producing more advanced models over the years, a lack of validation experiments made it difficult to have fully validated models. For this reason, experimental techniques which can provide insights into the local dynamics of joints can be of great interest for the refinement of such models and for the optimisation of the joint design and local wear predictions. In this paper, a preliminary study is presented where ultrasound waves are used to characterise the local dynamics of friction contacts by observing changes of the ultrasound reflection/transmission at the friction interface. The experimental technique is applied to a dynamic friction rig, where two steel specimens are rubbed against each other under a harmonic tangential excitation. Initial results show that, with a controlled experimental test procedure, this technique can identify microslip effects at the contact interface.
- Published
- 2019
35. A Test-Case on Continuation Methods for Bladed-Disk Vibration with Contact and Friction
- Author
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Hartmut Hetzler, Luca Pesaresi, Zeeshan Saeed, G. Jenovencio, Loic Salles, J. Blahoš, A. Sudhakar, F. El Haddad, Jie Yuan, and S. Arul
- Subjects
Model order reduction ,Frequency response ,Cyclic symmetry ,Computer science ,business.industry ,020209 energy ,Computation ,Continuation method ,02 engineering and technology ,Structural engineering ,Nonlinear forced response ,01 natural sciences ,Turbine ,010305 fluids & plasmas ,Vibration ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,Benchmark (computing) ,MHBM ,Shroud ,Bladed-disk ,business ,Joint (geology) ,Bladed-disk, Cyclic symmetry, Nonlinear forced response, MHBM, Continuation method - Abstract
Bladed-disks in turbo-machines experience harsh operating conditions and undergo high vibration amplitudes if not properly damped. Friction at the blade-to-blade or blade-to-disk interfaces plays a key role in dampening the high amplitudes. Due to the inherent complexity of these structures and non-linearities introduced by the friction joints, accurate response prediction becomes very difficult. There are variety of methods in the literature to predict non-linear vibration due to contact friction. However, their application to the bladed-disks remains limited. Furthermore, there are not many 3D realistic test-cases in the open literature for testing those methods and serve as a benchmark. A bladed-disk representative of a real turbine is presented as an open numerical test-case for the research community. It is characterized by a blade root joint and a shroud joint. The bladed-disk sector is meshed in different ways along with component mode synthesis (CMS) model order reduction for onward non-linear computations. The steady-state solution is obtained by multi-Harmonic Balance method and then continuation method is employed to predict the non-linear frequency response. Thus, it can serve as a case for testing previous and new methods as well as a benchmark for comparative studies.
- Published
- 2019
- Full Text
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36. The impact of fretting wear on structural dynamics: experiment and simulation
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Loic Salles, Christoph W. Schwingshackl, M. Volvert, Alfredo Fantetti, I. Lawal, Lejie Liu, David Nowell, Lakshminarayana Reddy Tamatam, Matthew R. W. Brake, and Commission of the European Communities
- Subjects
Materials science ,Fretting wear ,Nonlinear dynamics ,Hysteresis loops ,Friction coefficient ,Contact stiffness ,02 engineering and technology ,Measure (mathematics) ,0203 mechanical engineering ,medicine ,Mechanical Engineering & Transports ,Mechanical Engineering ,Dynamics (mechanics) ,Stiffness ,Surfaces and Interfaces ,Mechanics ,021001 nanoscience & nanotechnology ,Surfaces, Coatings and Films ,Tangential contact ,Hysteresis ,Nonlinear system ,020303 mechanical engineering & transports ,Mechanics of Materials ,medicine.symptom ,0210 nano-technology ,0913 Mechanical Engineering - Abstract
This paper investigates the effects of fretting wear on frictional contacts. A high frequency friction rig is used to measure the evolution of hysteresis loops, friction coefficient and tangential contact stiffness over time. This evolution of the contact parameters is linked to significant changes in natural frequencies and damping of the rig. Hysteresis loops are replicated by using a Bouc-Wen modified formulation, which includes wear to simulate the evolution of contact parameters and to model the evolving dynamic behaviour of the rig. A comparison of the measured and predicted dynamic behaviour demonstrates the feasibility of the proposed approach and highlights the need to consider wear to accurately capture the dynamic response of a system with frictional joints over its lifetime.
- Published
- 2019
37. Dissipative solitons in forced cyclic and symmetric structures
- Author
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Loic Salles, Sophoclis Patsias, Amin Chabchoub, Norbert Hoffmann, Alan R Champneys, Aurélien Grolet, Francesco Fontanela, Department of Mechanical Engineering [Imperial College London], Imperial College London, Laboratoire d’Ingénierie des Systèmes Physiques et Numériques (LISPEN), Arts et Métiers Sciences et Technologies, HESAM Université (HESAM)-HESAM Université (HESAM), School of Civil and Environmental Engineering [Sydney], University of New South Wales [Sydney] (UNSW), Faculty of Engineering [Bristol], University of Bristol [Bristol], Rolls Royce PLC, and Hamburg University of Technology (TUHH)
- Subjects
0209 industrial biotechnology ,FOS: Physical sciences ,Aerospace Engineering ,Pattern Formation and Solitons (nlin.PS) ,02 engineering and technology ,01 natural sciences ,Solitons ,Cyclic structures ,Mécanique: Vibrations [Sciences de l'ingénieur] ,020901 industrial engineering & automation ,0103 physical sciences ,Turbomachinery ,010301 acoustics ,Travelling wave excitation ,Bifurcation ,Civil and Structural Engineering ,Physics ,Mechanical Engineering ,[SPI.MECA.VIBR]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Vibrations [physics.class-ph] ,Vibration localisation ,Aerodynamics ,Nonlinear Sciences - Pattern Formation and Solitons ,Symmetry (physics) ,Computer Science Applications ,Vibration ,Nonlinear system ,Classical mechanics ,Control and Systems Engineering ,Signal Processing ,Dissipative system ,Excitation - Abstract
The emergence of localised vibrations in cyclic and symmetric rotating struc-tures, such as bladed disks of aircraft engines, has challenged engineers in thepast few decades. In the linear regime, localised states may arise due to alack of symmetry, as for example induced by inhomogeneities. However, whenstructures deviate from the linear behaviour, e.g. due to material nonlinearities,geometric nonlinearities like large deformations, or other nonlinear elements likejoints or friction interfaces, localised states may arise even in perfectly symmet-ric structures. In this paper, a system consisting of coupled Duffing oscillatorswith linear viscous damping is subjected to external travelling wave forcing.The system may be considered a minimal model for bladed disks in turboma-chinery operating in the nonlinear regime, where such excitation may arise dueto imbalance or aerodynamic excitation. We demonstrate that near the reso-nance, in this non-conservative regime, localised vibration states bifurcate fromthe travelling waves. Complex bifurcation diagrams result, comprising stableand unstable dissipative solitons. The localised solutions can also be continuednumerically to a conservative limit, where solitons bifurcate from the backbonecurves of the travelling waves at finite amplitudes.
- Published
- 2019
- Full Text
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38. Computation of quasi-periodic localised vibrations in nonlinear cyclic and symmetric structures using harmonic balance methods
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Filipe Fontanela, Aurélien Grolet, Norbert Hoffmann, Loic Salles, Imperial College London, Laboratoire d’Ingénierie des Systèmes Physiques et Numériques (LISPEN), Arts et Métiers Sciences et Technologies, HESAM Université (HESAM)-HESAM Université (HESAM), and Hamburg University of Technology (TUHH)
- Subjects
Acoustics and Ultrasonics ,Computation ,media_common.quotation_subject ,02 engineering and technology ,Minimal models ,Inertia ,01 natural sciences ,Cyclic structures ,Mécanique: Vibrations [Sciences de l'ingénieur] ,Harmonic balance ,Harmonic balance methods ,0203 mechanical engineering ,0103 physical sciences ,Energy localisation ,010301 acoustics ,media_common ,Physics ,[PHYS.MECA.VIBR]Physics [physics]/Mechanics [physics]/Vibrations [physics.class-ph] ,Mechanical Engineering ,Mathematical analysis ,[PHYS.MECA]Physics [physics]/Mechanics [physics] ,Condensed Matter Physics ,Quasi-periodic vibrations ,Vibration ,Nonlinear system ,020303 mechanical engineering & transports ,Amplitude ,Mechanics of Materials ,Dissipative system - Abstract
International audience; In this paper we develop a fully numerical approach to compute quasi-periodic vibrations bifurcating from nonlinear periodic states in cyclic and symmetric structures. The focus is on localised oscillations arising from modulationally unstable travelling waves induced by strong external excitations. The computational strategy is based on the periodic and quasi-periodic harmonic balance methods together with an arc-length continuation scheme. Due to the presence of multiple localised states, a new method to switch from periodic to quasi-periodic states is proposed. The algorithm is applied to two different minimal models for bladed disks vibrating in large amplitudes regimes. In the first case, each sector of the bladed disk is modelled by a single degree of freedom, while in the second application a second degree of freedom is included to account for the disk inertia. In both cases the algorithm has identified and tracked multiple quasi-periodic localised states travelling around the structure in the form of dissipative solitons.
- Published
- 2019
- Full Text
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39. A Study of the Contact Interface for Compressor Blisks with Ring Dampers Using Nonlinear Modal Analysis
- Author
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Jie Yuan, Yekai Sun, Enora Denimal, and Loic Salles
- Subjects
Nonlinear system ,Integrally closed ,Materials science ,Modal ,business.industry ,Normal mode ,Turbomachinery ,TJ ,Aerodynamics ,Structural engineering ,business ,Gas compressor ,Damper - Abstract
The integrally bladed disks, also known as blisks, have been widely used in industrial turbomachinery because of their benefits in aerodynamic performance and mass reduction. Friction damping is considered as the major damping sources in turbomachinery. However, in blisks, the friction damping is negligible due to the lack of the contact interfaces. The friction ring dampers are one of the emerging external damping sources for blisks. In this paper, a full-scale blisk with a friction ring damper is studied, where a 3D contact element is used to compute the contact frictions. The blisk and ring damper is investigated using their damped nonlinear normal modes. The modal damping can be directly calculated and used to quantify the friction damping generated by the ring damper. The contact behaviour within the contact interface is further analysed. The nodes with initial gap show less damping ability. The separations within the contact interface are expected to be avoided to achieve a better damping performance.
- Published
- 2021
- Full Text
- View/download PDF
40. Numerical and Experimental Investigation of an Underplatform Damper Test Rig
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J. S. Green, Loic Salles, Luca Pesaresi, A. Jones, Christoph W. Schwingshackl, and R. Elliott
- Subjects
Engineering ,business.industry ,Process (computing) ,Resonance ,02 engineering and technology ,General Medicine ,Structural engineering ,Aeroelasticity ,01 natural sciences ,Turbine ,Damper ,Vibration ,Nonlinear system ,020303 mechanical engineering & transports ,0203 mechanical engineering ,0103 physical sciences ,Sensitivity (control systems) ,business ,010301 acoustics - Abstract
During operation mechanical structures can experience large vibration amplitudes. One of the challenges encountered in gas-turbine blade design is avoiding high-cycle fatigue failure usually caused by large resonance stresses driven by aeroelastic excitation. A common approach to control the amplitude levels relies on increasing friction damping by incorporating underplatform dampers (UPD). An accurate prediction of the dynamics of a blade-damper system is quite challenging, due to the highly nonlinear nature of the friction interfaces and detailed validation is required to ensure that a good modelling approach is selected. To support the validation process, a newly developed experimental damper rig will be presented, based on a set of newly introduced non-dimensional parameters that ensure a similar dynamic behaviour of the test rig to a real turbine blade-damper system. An ini- tial experimental investigation highlighted the sensitivity of the measured response with regards to settling and running in of the damper, and further measurements identified a strong dependence of the nonlinear behaviour to localised damper motion. Numerical simulations of the damper rig with a simple macroslip damper model were performed during the preliminary design, and a comparison to the measured data highlighted the ability of the basic implicit model to capture the resonance frequencies of the system accuratelyю
- Published
- 2016
- Full Text
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41. Design and Testing of a Co-Rotating Vibration Excitation System
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Angelos, Filippatos, Tino, Wollmann, Minh, Nguyen, Pawel, Kostka, Martin, Dannemann, Albert, Langkamp, Loic, Salles, and Maik, Gude
- Subjects
structural dynamic behaviour ,vibration excitation ,rotor ,Article ,rotational testing - Abstract
A vibration excitation system (VES) in a form of an active coupling is proposed, designed and manufactured. The system is equipped with a set of piezoelectric stack actuators uniformly distributed around the rotor axis and positioned parallel to each other. The actuator arrangement allows an axial displacement of the coupling halves as well as their rotation about any transverse axis. Through the application of the VES an aimed vibration excitation is realised in a co-rotating coordinate system, which enables a non-invasive and precise modal analysis of rotating components. As an example, the VES is applied for the characterisation of the structural dynamic behaviour of a generic steel rotor at different rotational speeds. The first results are promising for both stationary and rotating conditions.
- Published
- 2018
42. Nonlinear vibrational analysis for integrally bladed disk using frictional ring damper
- Author
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Yekai Sun, Luca Pesaresi, Loic Salles, and Jie Yuan
- Subjects
History ,Materials science ,Vibrational energy ,020209 energy ,Fatigue testing ,02 engineering and technology ,Mechanics ,Ring (chemistry) ,01 natural sciences ,Computer Science Applications ,Education ,Damper ,010101 applied mathematics ,Integrally closed ,Nonlinear system ,0202 electrical engineering, electronic engineering, information engineering ,TJ ,0101 mathematics - Abstract
The use of integrally bladed-disk is now very popular in turbomachinery industry since they feature significant aerodynamic and structural improvements along with a significant mass reduction. However, these integrated single structures can arise a major high cycle fatigue issue due to the lack of sufficient damping for dissipating the vibrational energy. This work describes a numerical investigation of the nonlinear dynamic behaviour and nonlinear normal mode for such a bladed-disk with frictional ring damper using the Harmonic Balanced Method (HBM) with alternating Fourier transformation. Jenkins element is used to model the nonlinear contact friction between the disc and ring damper. Using such a modeling strategy, the modal damping and resonance amplitude are directly and efficiently computed through nonlinear normal mode analysis. The initial results show the vibrational level on the blades can be effectively controlled by the parameters of the ring damper model. The effectiveness of ring damper and damping performance is evaluated. This study also indicates the nonlinear normal mode analysis based HBM may be an effective method to analyse the dynamic behaviour of the integrated bladed-disk with frictional ring damper.
- Published
- 2018
43. A modelling approach for the nonlinear dynamics of assembled structures undergoing fretting wear
- Author
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J. Armand, Luca Pesaresi, Chian Wong, Loic Salles, and Christoph W. Schwingshackl
- Subjects
Materials science ,020209 energy ,General Mathematics ,General Engineering ,General Physics and Astronomy ,02 engineering and technology ,Surface finish ,Mechanics ,Nonlinear system ,Fretting wear ,020303 mechanical engineering & transports ,0203 mechanical engineering ,0202 electrical engineering, electronic engineering, information engineering ,Excitation ,Research Article - Abstract
Assembled structures tend to exhibit nonlinear dynamic behaviour at high excitation levels due to the presence of contact interfaces. The possibility of building predictive models relies on the ability of the modelling strategy to capture the complex nonlinear phenomena occurring at the interface. One of these phenomena, normally neglected, is the fretting wear occurring at the frictional interface. In this paper, a computationally efficient modelling approach which enables considerations of the effect of fretting wear on the nonlinear dynamics is presented. A multi-scale strategy is proposed, in which two different time scales and space scales are used for the contact analysis and dynamic analysis. Thanks to the de-coupling of the contact and dynamic analysis, a more realistic representation of the contact interface, which includes surface roughness, is possible. The proposed approach is applied to a single bolted joint resonator with a simulated rough contact interface. A tendency towards an increase of real contact area and contact stiffness at the interface is clearly observed. The dynamic response of the system is shown to evolve over time, with a slight decrease of damping and an increase of resonance frequency, highlighting the impact of fretting wear on the system dynamics.
- Published
- 2018
44. An advanced underplatform damper modelling approach based on a microslip contact model
- Author
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Luca Pesaresi, Christoph W. Schwingshackl, Chian Wong, J. Armand, Loic Salles, Imperial College London, Rolls Royce PLC, and Innovate UK
- Subjects
Technology ,Acoustics and Ultrasonics ,Turbine blade ,Computer science ,LOADS ,02 engineering and technology ,Mechanics ,Turbine ,VIBRATIONS ,09 Engineering ,law.invention ,Damper ,[SPI]Engineering Sciences [physics] ,Engineering ,ROUGH SURFACES ,0203 mechanical engineering ,law ,FORCED RESPONSE ANALYSIS ,Surface roughness ,TURBINE APPLICATIONS ,KINEMATICS ,Microslip model ,ComputingMilieux_MISCELLANEOUS ,FRICTION DAMPERS ,[SPI.ACOU]Engineering Sciences [physics]/Acoustics [physics.class-ph] ,Science & Technology ,02 Physical Sciences ,business.industry ,Mechanical Engineering ,NONLINEAR DYNAMICS ,BLADED DISKS ,Friction damping ,Structural engineering ,Acoustics ,Dissipation ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Vibration ,Engineering, Mechanical ,Nonlinear system ,020303 mechanical engineering & transports ,Damper model ,Mechanics of Materials ,HARMONIC-BALANCE METHOD ,Profilometer ,Turbine blade vibrations ,0210 nano-technology ,business - Abstract
High-cycle fatigue caused by large resonance stresses remains one of the most common causes of turbine blade failures. Friction dampers are one of the most effective and practical solutions to limit the vibration amplitudes, and shift the resonance frequencies of the turbine assemblies far from operating speeds. However, predicting the effects of underplatform dampers on the dynamics of the blades with good accuracy still represents a major challenge today, due to the complex nature of the nonlinear forces at the interface, characterised by transitions between stick, slip, and separation conditions. The most common modelling approaches developed recently are based on the explicit FE model for the damper, and on a dense grid of 3D contact elements comprised of Jenkins elements, or on a single 2D microslip element on each surface. In this paper, a combination of the two approaches is proposed. A 3D microslip element, based on a modified Valanis model is proposed and a series of these elements are used to describe the contact interface. This new approach allows to implicitly account for the microscale energy dissipation as well as the pressure-dependent contact stiffness caused by the roughness of the contact surface. The proposed model and its predicting capabilities are then evaluated against a simplified blade-damper model, based on an underplatform damper test rig recently developed by the authors. A semi-analytical contact solver is used to tune the parameters of the contact element starting from the profilometer measurements of the real damper surface. A comparison with a more simplistic modelling approach based on macroslip contact elements, highlights the improved accuracy of the new model to predict the experimental nonlinear response, when information about the surface roughness is available.
- Published
- 2018
- Full Text
- View/download PDF
45. Comparison of Computational Generalized and Standard Eigenvalue Solutions of Rotating Systems
- Author
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Alexander H. Haslam, Christoph W. Schwingshackl, Loic Salles, and Ali Tatar
- Subjects
Timoshenko beam theory ,Vibration ,Normal mode ,Modal analysis ,Quadratic eigenvalue problem ,Mathematical analysis ,Equations of motion ,Eigenvalues and eigenvectors ,Finite element method ,Mathematics - Abstract
Modal analysis is regularly used to compute natural frequencies and mode shapes of structures via eigenvalue solutions in vibration engineering. In this paper, the eigenvalue problem of a 6 degrees of freedom rotating system with gyroscopic effects, including axial, torsional and lateral motion, is investigated using Timoshenko beam theory. The main focus thereby is the investigation of the computational time and the numerical errors in generalized and standard eigenvalue solutions of rotating systems. The finite element method is employed to compute the global stiffness, mass and gyroscopic matrices of the rotating system. The equations of motion is expressed in the state space form to convert the quadratic eigenvalue problem into the generalized and standard forms. The number of elements in the finite element model was varied to investigate the convergence of the natural frequencies and the computational performance of the two eigenvalue solutions. The numerical analyses show that the standard eigenvalue solution is significantly faster than the generalized one with increasing number of elements and the generalized eigenvalue solution can yield wrong solutions when using higher numbers of elements due to the ill-conditioning phenomenon. In this regard, the standard eigenvalue solution gives more reliable results and uses less computational time than the generalized one.
- Published
- 2018
- Full Text
- View/download PDF
46. Numerical Assessment of Reduced Order Modeling Techniques for Dynamic Analysis of Jointed Structures With Contact Nonlinearities
- Author
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Jie Yuan, Fadi El-haddad, Loic Salles, and Chian Wong
- Subjects
Frequency response ,Materials science ,business.industry ,Mechanical Engineering ,Energy Engineering and Power Technology ,Aerospace Engineering ,Stiffness ,Numerical assessment ,02 engineering and technology ,Structural engineering ,01 natural sciences ,Finite element method ,Reduced order ,020303 mechanical engineering & transports ,Fuel Technology ,0203 mechanical engineering ,Nuclear Energy and Engineering ,0103 physical sciences ,medicine ,Displacement (orthopedic surgery) ,medicine.symptom ,business ,010301 acoustics ,Excitation - Abstract
This work presents an assessment of classical and state of the art reduced order modeling (ROM) techniques to enhance the computational efficiency for dynamic analysis of jointed structures with local contact nonlinearities. These ROM methods include classical free interface method (Rubin method, MacNeal method), fixed interface method Craig-Bampton (CB), Dual Craig-Bampton (DCB) method and also recently developed joint interface mode (JIM) and trial vector derivative (TVD) approaches. A finite element (FE) jointed beam model is considered as the test case taking into account two different setups: one with a linearized spring joint and the other with a nonlinear macroslip contact friction joint. Using these ROM techniques, the accuracy of dynamic behaviors and their computational expense are compared separately. We also studied the effect of excitation levels, joint region size, and number of modes on the performance of these ROM methods.
- Published
- 2018
- Full Text
- View/download PDF
47. Solitons in Cyclic and Symmetric Structures
- Author
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Norbert Hoffmann, Filipe Fontanela, Aurélien Grolet, Loic Salles, Imperial College London, Laboratoire d’Ingénierie des Systèmes Physiques et Numériques (LISPEN), Arts et Métiers Sciences et Technologies, and HESAM Université (HESAM)-HESAM Université (HESAM)
- Subjects
Physics ,harmonic balance methods ,Harmonic balance method ,Plane wave ,non-linear Schrödinger equation ,Dissipation ,01 natural sciences ,010305 fluids & plasmas ,Schrödinger equation ,Minimal model ,Vibration ,symbols.namesake ,Harmonic balance ,cyclic structures ,Classical mechanics ,[SPI.MECA.STRU]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Structural mechanics [physics.class-ph] ,localised vibrations ,0103 physical sciences ,solitons ,symbols ,Traveling wave ,010301 acoustics ,Excitation - Abstract
International audience; This research focuses on localised states arising from modulationally unstable plane waves in non-conservative cyclic and symmetric structures. The main application is on vibrations of bladed-disks of aircraft engines experiencing non-linear effects, such as large displacements, friction dissipation, and/or complex fluid-structure interactions. The investigation is based on a minimal model composed of a chain of linearly damped Duffing oscillators under external travelling wave excitation. The computed results are based on two strategies: (1) a Non-Linear Schrödinger Equation (NLSE) approximation; and (2) the periodic and quasi-periodic Harmonic Balance Methods (HBM). In both cases, the results show that unstable plane waves may self-modulate, leading to stable and unstable single and multiple solitons configurations.
- Published
- 2018
- Full Text
- View/download PDF
48. A novel penalty-based reduced order modelling method for dynamic analysis of joint structures
- Author
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Sophoclis Patsias, Loic Salles, Jie Yuan, Chian Wong, Fehr, Jörg, and Haasdonk, Bernard
- Subjects
Dynamic simulation ,Variable (computer science) ,Basis (linear algebra) ,Control theory ,Normal mode ,Computer science ,Mechanical joint ,Equations of motion ,TJ ,Galerkin method ,Projection (linear algebra) - Abstract
This work proposes a new reduced order modelling method to improve the computational efficiency for the dynamic simulation of a jointed structures with localized contact friction non-linearities. We reformulate the traditional equation of motion for a joint structure by linearising the non-linear system on the contact interface and augmenting the linearised system by introducing an internal non-linear penalty variable. The internal variable is used to compensate the possible non-linear effects from the contact interface. Three types of reduced basis are selected for the Galerkin projection, namely, the vibration modes (VMs) of the linearised system, static modes (SMs) and also the trial vector derivatives (TVDs) vectors. Using these reduced basis, it would allow the size of the internal variable to change correspondingly with the number of active non-linear DOFs. The size of the new reduced order model therefore can be automatically updated depending on the contact condition during the simulations. This would reduce significantly the model size when most of the contact nodes are in a stuck condition, which is actually often the case when a jointed structure vibrates. A case study using a 2D joint beam model is carried out to demonstrate the concept of the proposed method. The initial results from this case study is then compared to the state of the art reduced order modeling.
- Published
- 2018
49. Reduced Order Modeling of Nonlinear Structures with Frictional Interfaces
- Author
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Matthew R. W. Brake, Christoph W. Schwingshackl, J. Armand, Loic Salles, Robert M. Lacayo, Johann Groß, and Pascal Reuß
- Subjects
Nonlinear system ,Harmonic balance ,Computer science ,020209 energy ,0202 electrical engineering, electronic engineering, information engineering ,Structure (category theory) ,Numerical modeling ,02 engineering and technology ,Transient (oscillation) ,Mechanics ,Joint (geology) ,Reduced order - Abstract
Over the past decade, a number of phenomenologically different approaches to modeling and simulating the dynamics of a jointed structure have been proposed. This chapter presents and assesses multiple modeling techniques to predict the nonlinear dynamic behavior of a bolted lab joint, including frequency based sub-structuring methods, harmonic balance methods, and nonlinearly coupled reduced order model transient simulations. The regimes in which each method is best suited are identified, and recommendations are made for how to select a modeling method and for advancing numerical modeling of discrete nonlinearities.
- Published
- 2017
- Full Text
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50. Analysis of a Turbine Bladed Disk With Structural and Aerodynamic Mistuning
- Author
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Sina Stapelfeldt, Dimitri Franz, and Loic Salles
- Subjects
Turbine blade ,business.industry ,law ,Flutter ,Aerodynamics ,Structural engineering ,Mistuning ,business ,Turbine ,Mathematics ,law.invention - Abstract
In this paper the effects of mistuning on the flutter stability of a turbine blade are analysed. Two types of mistuning are considered, frequency mistuning and aerodynamic mistuning. The study concentrates on the the first family of modes (1F, first flap) as the blade fluttered in this mode during test. For the frequency mistuning analysis, the 1F frequency is varied around the annulus but the 1F mode shapes remain the same for all the blades. The mistuning analyses are performed by using a reduced order model (ROM) based on an eigenvalue analysis of the linearized modal aeroelastic system with the aerodynamic matrix calculated from the aerodynamic influence coefficients. The influence coefficients required for this algorithm are obtained from a three-dimensional, non-linear aeroelastic solver (AU3D) by shaking one blade in the datum (tuned) frequency and mode and recording aerodynamic forces on the other blades in the assembly. After the ROM is validated against the non-linear method for the tuned case, it is used for the mistuning and mis-staggering study as time-domain computations of such cases are very time consuming. The results of this paper indicate that, frequency mistuning is always stabilizing but aerodynamic mistuning can be destabilizing under certain conditions. Moreover, it is shown that the effect of frequency mistuning is much higher than the one of aerodynamic asymmetries and that structural coupling limits the effects of mistuning.
- Published
- 2017
- Full Text
- View/download PDF
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