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Objective: Haemorrhagic transformation (HT) is one of the most common complications after ischaemic stroke. HT can be the result of stroke progression or a complication of reperfusion treatment for stroke. The aim of this study is to apply a previously proposed HT mathematical model within a computational whole brain model to determine the factors that affect the severity of HT. In addition, these simulations are directly compared with neuroimaging data. Approach: The MR CLEAN–NO IV trial assessed the effect of endovascular therapy (EVT) alone compared with intravenous alteplase treatment (IVT) followed by EVT for patients with acute ischaemic stroke due to anterior circulation large vessel occlusion. We included imaging data of 15 HT patients from the MR CLEAN–NO IV trial, 5 patients suffered from haemorrhagic infarction type 1, 5 from haemorrhagic infarction type 2 and 5 had parenchymal haematoma type 1. The comparison of simulations with patient image data is carried out by comparing the haematoma locations and haematoma volume. The parameters of the model are then optimised to improve agreement with clinical data. Finally, the model is used to investigate the factors that affect the severity of HT. Main results: Based on the computational whole brain model, we found that perfusion reduced by 5–16% after HT onset. The results are in good agreement with the clinical data. We then showed that 1% increase of blood viscosity reduces perfusion by 0.04% and increases haematoma volume by 10.35% from baseline, and 1% increase of blood pressure reduces perfusion by 0.80% and increases haematoma volume by 4.73% from baseline. These results indicate that increased blood glucose and hypertension (among other factors) both appear to lead to a higher severity of HT. Significance: This model, by enabling us to bridge the gap between the mathematical HT model and clinical imaging data, provides the first whole brain prediction model for HT severity assessment.

Wireless power transfer (WPT) is a technology used to transmit power using air as it medium of transfer. The function of the WPT is similar to a transformer. The power provided on the primary side will be transferred through air to the secondary side. The performance of the WPT is crucially depends on the air gap length, 𝛿 that separates primary and secondary side. In this paper discusses the performance of WPT using series-to-series topology. The performance of the WPT was estimated using finite element analysis (FEA). During the study, focus was given to effect of turn ratio, a, air gap length, 𝛿 and capacitor value at primary Cp, and secondary, Cs winding to voltage ratio of the WPT. The air gap length, 𝛿 was set to 1 and 2 mm while the capacitors were set depend on the ratio of primary to secondary winding capacitor, Cp/Cs. The WPT performance also being tested under no-load and loaded operation to observed it effect. As a result, the WPT with turn ratio, a at 0.37, air gap length, 𝛿 at 1 mm and ratio of primary to secondary winding capacitor, Cp/Cs at 0.5 produce the best voltage ratio compared to other settings.

Open caissons are an increasingly common means of constructing underground storage and attenuation tanks as well as launch and reception shafts for tunnel-boring machines. The caisson walls typically feature a tapered base, referred to as the ‘cutting face’, to aid the sinking process by reducing the vertical soil reaction. The primary aim of this paper is to explore the influence of the caisson cutting face inclination angle on the vertical soil reaction in sand. Both finite-element limit analysis and finite-element analysis are adopted for this purpose. The effects of cutting face roughness, external embedment depth and caisson radius are also investigated. The results show that the influence of the cutting face inclination angle on the bearing capacity is highly dependent on both the soil friction angle and the roughness of the cutting face. A reduction in the caisson radius is also shown to cause a significant increase in the vertical soil reaction. The numerical output is used to inform the development of a new closed-form analytical approach amenable for use in routine design. The design method is shown to provide a high-fidelity representation of the numerical output.

We investigate the application of the Galerkin finite element method to approximate a stochastic semilinear space–time fractional wave equation. The equation is driven by integrated additive noise, and the time fractional order α∈(1,2). The existence of a unique solution of the problem is proved by using the Banach fixed point theorem, and the spatial and temporal regularities of the solution are established. The noise is approximated with the piecewise constant function in time in order to obtain a stochastic regularized semilinear space–time wave equation which is then approximated using the Galerkin finite element method. The optimal error estimates are proved based on the various smoothing properties of the Mittag–Leffler functions. Numerical examples are provided to demonstrate the consistency between the theoretical findings and the obtained numerical results.

The membrane gas separation process has gained significant attention using the computational fluid dynamics (CFD) technique. This study considered the CFD method to find gas concentration profiles in a hollow fiber membrane (HFM) module to separate the binary gas mixture. The membrane was considered with a fiber thickness where each component’s mass fluxes could be obtained based on the local partial pressures, solubility, diffusion, and the membrane’s selectivity. COMSOL Multiphysics was used to solve the numerical solution at corresponding operating conditions and results were compared to experimental data. The two different mixtures, CO2/CH4 and N2/O2, were investigated to obtain concentration gradient and mass flux profiles of CO2 and O2 species in an axial direction. This study allows assessing the feed pressure’s impact on the HFM system’s overall performance. These results demonstrate that the increment in feed pressures decreased the membrane system’s separation performance. The impact of hollow fiber length indicates that increasing the active fiber length has a higher effective mass transfer region but dilutes the permeate-side purities of O2 (46% to 28%) and CO2 (93% to 73%). The results show that increasing inlet pressure and a higher concentration gradient resulted in higher flux through the membrane.

In order to pursue good crushing load uniformity and enchance energy absorption efficiency of conventional honeycombs, a kind of bio-inspired hierarchical honeycomb model is proposed by mimicking the arched crab shell structures. Three bio-inspired hierarchical honeycombs (BHHs) with different topologies are designed by replacing each vertex of square honeycombs with smaller arc-shaped structures. The effects of hierarchical topologies and multi-material layout on in-plane dynamic crushings and absorbed-energy capacities of the BHHs are explored based on the explicit finite element (FE) analysis. Different deformation modes can be observed from the BHHs, which mainly depend upon hierarchical topologies and impact velocities. According to energy efficiency method and one-dimensional (1D) shock theory, calculation formulas of densification strains and plateau stresses for the BHHs are derived to characterize the dynamic bearing capacity, which is consistent well with FE results. Compared with conventional honeycombs, the crushing load efficiency and energy absorption capacity of the BHHs can be improved by changing the proper hierarchical topology and multi-material layout. These researches will provide theoretical guidance for innovative design and dynamic response performance controllability of honeycombs.

A number of transport vehicles have been fitted with electric traction motors and their inverters. The traction motor is required to continue to operate even if the inverter is under fault conditions. We propose a motor with two controllable rotors for a traction motor, which consists of 2 rotors and 1 stator. In this paper, we propose a fault-tolerant control method for a two-controllable-rotor motor using a 6-phase inverter. The operational principle of the two-controllable-rotor motor is described. The mathematical model under fault tolerant control is shown, and a fault-tolerant control method for the two-controllable-rotor motor is described. The proposed fault tolerant control method is verified by conducting finite element analysis and carrying out measurements on a prototype.

Introduction: Functional near-infrared spectroscopy (fNIRS) is an imaging method in which a light source and detector are installed on the head; consequently, the re-emission of light from human skin contains information about cerebral hemodynamic alteration. The spatial probability distribution profile of photons penetrating tissue at a source spot, scattering into the tissue, and being released at an appropriate detector position, represents the spatial sensitivity. Methods: Modeling light propagation in a human head is essential for quantitative near-infrared spectroscopy and optical imaging. The specific form of the distribution of light is obtained using the theory of perturbation. An analytical solution of the perturbative diffusion equation (DE) and finite element method (FEM) in a Slab media (similar to the human head) makes it possible to study light propagation due to absorption and scattering of brain tissue. Results: The simulation result indicates that sensitivity is slowly decreasing in the deep area, and the sensitivity below the source and detector is the highest. The depth sensitivity and computation time of both analytical and FEM methods are compared. The simulation time of the analytical approach is four times larger than the FEM. Conclusion: In this paper, an analytical solution and the performance of FEM methods when applied to the diffusion equation for heterogeneous media with a single spherical defect are compared. The depth sensitivity along with the computation time of simulation has been investigated for both methods. For simple and Slab modes of the human brain, the analytical solution is the right candidate. Whenever the brain model is sophisticated, it is possible to use FEM methods, but it costs a higher computation time.

The dynamic response of the rotor system in a ring die granulator is complex and difficult to solve when it operates under joint external, support and gear mesh forces. To solve this problem, a finite element method and extrusion theory was applied in this study to develop a dynamic coupling model for a hollow overhung rotor with external load excitation. A Newmark-β numerical integration method was used to solve for the dynamic response of the overhung rotor under multiple excitation forces. The results included time-domain response diagrams, frequency-domain response diagrams, phase diagrams, Poincaré section diagrams, and bifurcation diagrams. The model and the method were verified by testing a ring die granulator. On this basis, the dynamic response of the system is predicted according to the influence of different parameters. As the bearing support distance increased, the roller eccentricity decreased, the bearing clearance decreased, the response of the rotor system was significantly optimized, and the system tended to stabilize gradually. Therefore, this paper provides a theoretical basis and experimental verification for the optimization of a pelleting machine transmission structure.

The paper studies strike-slip fault rupture propagation through dense sand and its interaction with surface foundations, combining physical and numerical modelling. A series of centrifuge tests is conducted using a three-section split-box, which allows the modelling of two strike-slip faults per test. A free-field test is initially conducted, followed by four interaction tests. Eight different foundation configurations are studied, varying the foundation location, surcharge load, aspect ratio and rigidity. The experiments are numerically simulated employing three-dimensional finite-element modelling, combining periodic boundaries and a relatively simple yet efficient constitutive model, developed as part of this study. Based on a Mohr–Coulomb yield criterion, the model incorporates post-yield isotropic frictional hardening and softening (MC–HS). Carefully calibrated on the basis of triaxial tests, the model is validated against the centrifuge model tests, and exploited to derive further insights. The MC–HS model covers the entire range from elastic to fully softened response, capturing the deviatoric and volumetric behaviour of dense sand, and especially its pre-softening volumetric response, which is proven to be crucial for the simulation of the complex mechanisms of strike-slip faulting. Both physical and numerical modelling reveal the formation of diagonal shear ruptures at the ground surface (Riedel shears). These are complex helicoidal structures, formed due to the spatial variation of shear stresses. Foundation response is mainly governed by the kinematic constraint offered by its presence. Fault rupture locations close to its sides typically lead to a translational mechanism, whereas locations close to its centreline lead to a rotational one. Foundation rigidity is proven to be a prerequisite for the development of both mechanisms, which rely on the ability of the foundation to resist the developing normal and shear stresses.

Lamb waves occur in thin-walled structures in two wave modes, the symmetric and antisymmetric mode. Their oscillation on the structures‘ surfaces is either in phase (symmetric) or shifted by a phase angle of π (antisymmetric). In this work, a method is developed to compare the surfaces‘ oscillation phase relation. It is based on the evaluation of time signals regarding the instantaneous phase angle using the continuous wavelet transformation and as a comparative method the short-time Fourier transformation. For this purpose, numerical simulations utilizing the finite element method provide time signals from the top and bottom surface of different thin-walled structures. They differ with respect to their material settings and laminate configurations. The numerically obtained time signals are evaluated by the developed methods. The occurring oscillation phase differences on the top and bottom surface are studied and both methods are compared. Subsequently, the oscillation phase is evaluated experimentally for the wave propagation in a fiber metal laminate. It is shown that the method based on the continuous wavelet transformation is suitable for the evaluation of oscillation phase relations in time signals. Additionally, it is proven that fiber metal laminates show only two phase relations which indicates the occurrence of Lamb waves.

This study presents finite element analysis of double split tee (DST) connections with high-strength steel bolts and coupled split tee sections, to evaluate various cyclic response parameters and elements. The investigation included quantifying connection behavior and hysteretic response, damage indexes, and failure modes. Over 40 specimens were simulated in ABAQUS under cyclic loading, including shape memory alloy (SMA)-built specimens. In the post-analysis phase, the T-stub thickness, the T-stub yield strength, the bolt preload and bolt number, and the stiffener type and stiffener material for the most significant parts of the DST connection were calculated. Simulation results showed that a lower ultimate moment yielded fewer needed stem bolts. The energy dissipation (ED) capacity increased as the horizontal distance between the stem bolts decreased. Additionally, increasing the strength of the bolt and T-stub by 15% resulted in a 3.86% increase in residual displacement (RD) for the bolt and a 1.73% decrease in residual displacement for the T-stub. T-stub stiffeners enhanced ED capacity by 31.7%. SMA materials were vulnerable to mode 1 failure when used in T-stubs, bolts, or stiffeners. However, the use of SMA increased the rate of energy dissipation. Adding stiffeners to the T-stubs altered the failure indexes and improved the pattern of failure modes. In addition, stiffeners decreased the rupture and pressure indexes. As a result, the failure index of a T-stub shifted from brittle failure to ductile failure.

The dynamic process of an underwater explosion (UNDEX) bubble in the vicinity of deformable structures is a complex phenomenon that has been studied by many researchers. The dynamic process of a UNDEX bubble is a complex transient problem that results in a highly distorted bubble and large deformation of the structure. The previous work has introduced various solutions for studying the interaction between the UNDEX bubble and deformable structure. The interaction between the bubble and nearby structures has been widely solved by the combination of the boundary element method (BEM) and the finite element method (FEM). However, this couple requires tight time-step controlling, long-time analysis, and large computer resources. Furthermore, this combination is not widely used as the FEM code in commercially available software for solving UNDEX bubble problems. This paper presents a coupled Eulerian-Lagrangian (CEL) approach in commercial software to deal with the fluid-structure interaction (FSI). The numerical model of a UNDEX bubble is first developed and verified by comparing results with experimental, BEM, and empirical data. Then both bubble behavior and structural deformation are examined in various case studies. The numerical results show that the stiffness of the structure has strongly influenced the bubble behavior and the water jet development. The pressure pulse becomes significantly large as the bubble collapse. Besides, this numerical approach also can reproduce crucial phenomena of a UNDEX bubble, such as the whipping effect and water jet attacks. Although the numerical model is developed using simplified boundary conditions, the proposed approach shows the feasibility of simulating the important features of a UNDEX bubble process as well as the response of nearby structures.

In this paper, the lateral limiting pressure on rectangular pile groups in undrained soil is explored using two−dimensional finite element modelling. The primary aim of the study is to assess the influence of pile group shape effects on the soil limiting pressured offered by the deep ‘flow-around’ failure mechanism, and associated soil failure mechanisms, considering both a small (four piles) and large (36 piles) group. Additional parameters considered in the modelling include pile spacing and pile-soil interface roughness. The finite element results show that group shape has a significant influence on the behaviour of closely spaced pile groups. In particular, the number of piles parallel to the direction of loading is shown to dominate the lateral bearing capacity factor such that significant increases in capacity efficiency can be achieved by slight modifications to the group shape for a given number of piles. The load-sharing across the group, traditionally defined using p-multipliers, was also shown to be highly non-uniform and dependent on group size, pile soil roughness and group geometry in addition to the pile spacing. The finite element output is presented in the form of design charts for the determination of group p-multipliers whereas a library of existing design solutions is presented for the calculation of the overall group response.

This paper reports the development of an architecture and software implementation of the library of classes for the finite-element analysis of problems in the theory of elasticity with an open-source code. The practical necessity of such systems is due to the fact that in modern equipment there are new types of materials whose structural elements' calculation has certain features. As a result, it is necessary to update the relevant scientific software or even devise a new one. A flexible software architecture is designed to reduce the time and complexity of such updates. Existing implementations of the method of finite elements with open source have been analyzed: it was revealed that there are no systems aimed at the most flexible and user-friendly architecture. The system of abstract classes proposed in the current work corresponds to known SOLID principles of object-oriented design and makes it possible to scale the already developed analysis program for new tasks in an easy and understandable way. To test the quality of the developed system from the point of view of software engineering, the maintainability index and cyclomatic complexity code metrics were used. The values of these metrics for the modules of the PyFEM system core vary in the following ranges: from 1 to 18 for the maintainability index, and from 22 to 100 for cyclomatic complexity. PyFEM testing was performed on the task of determining the stressed-strained state of the turbine rotor blade. Due to the ease of implementation, it was possible to build a set of effective and intuitive classes that make it possible to solve numerically the static and dynamic problems in the theory of elasticity. The developed class library can be used in the development of both universal and specialized software designed to analyze multiphysics problems.

Objective: The development of the ship hull assembly pro-cess is possible by changing the method of assembly of basic parts at the building site, which would shorten the duration of the process and lead to cost reduction. One of the pos-sibilities is to increase the dimensions and mass of basic building units, as well as the crane capacity at the building site.Methods: Ship hull assembly methods involving sections, blocks and modules are used in the hull assembly phase. In the world’s best shipyards, ships are built from blocks or modules, in which as much equipment as possible is in-stalled. This paper uses the finite element method (FEM) for structural analysis, and its results serve to define the opti-mal technological instructions for the vertical transport of ship hull structure blocks.Results: The development of the ship hull assembly sub-pro-cess can be achieved by using the hull block assembly meth-od instead of the hull section assembly method. For the ship presented in this paper, the mass of a block transported to the building site was increased 3 times, so the number of building units was reduced by 65%. This reduces trans-port activities on the building site and shortens the dura-tion of the assembly process by 20%. This paper shows that strengthening the block structure with temporary stiffen-ers is necessary for safe transport. It is possible to optimize their number and layout by using structural analysis.Conclusion: The development of numerical finite element methods, software packages, and computers allow wider use of structural analysis in solving engineering problems in shipbuilding technology. The simulation of realistic sit-uations, a wide range of analyses and a large number of results become possible, and they raise the level of knowledge and enable better decision-making in the pro-duction process.

This work is concerned with the numerical modeling of the Darcy flow and solute transport in fractured porous media for which the fractures are modeled as interfaces of codimension one. The hybrid-dimensional flow and transport problems are discretizaed by a lumped piecewise linear finite element method, combined with the algebraic correction of the convective fluxes. The resulting transport discretization can be interpreted as a conservative finite volume scheme that satisfies the discrete maximum principle, while introducing a very limited amount of numerical diffusion. In the context of fractured porous media flow the CFL number may vary by several order of magnitude, which makes explicit time stepping unfeasible. To cope with this difficulty we propose an adaptive semi-implicit time stepping strategy that reduces to the low order linear implicit discretization in the high CFL regions that include, but may not be limited to the fracture network. The performance of the fully explicit and semi-implicit variants of the method are investigated through the numerical experiment.

In microrobotics field, self-reconfigurable modular robots (SRMRs) offer several advantages including adaptation to uneven environments, the capability of handling various sets of tasks, and continuous operation in the case of a malfunction of a single module. The current research direction in self-reconfigurable robotic systems is towards reaching million level number of modules working in coherence by means of locomotion, self-reconfiguration, and information flow. This research direction comes with new challenges such as miniaturizing the modules. One should consider looking for alternative ways of locomotion and self-reconfiguration when dealing with SRMRs having million level number of modules. Externally actuating the modules can be a good alternative to micro SRMRs. In this study, we developed a novel motion mechanism for a single module in a micro SRMR system by using external magnetic actuators. An assembly of elastic microtubes and permanent magnets is attached inside a cube-shaped module and periodic motion of the assembly is applied. The motion of a single microtube with permanent magnets inside is generated by using COMSOL Multiphysics software. The results of the simulations are compared with theoretical values to validate the motion mechanism that is introduced in the study. Mikro robotik alanında, kendi kendini konfigüre edebilen modüler robotlar (KKMR) düzensiz çevreye uyum sağlayabilme, birçok değişken görevi yerine getirebilme ve tekil modüllerin arızalanması durumunda operasyonu sürdürebilme gibi avantajlar sunmaktadır. Kendi kendini konfigüre edebilen robotik sistemlerdeki son güncel araştırmalar, milyon seviyesinde modül sayısına sahip sistemlerin hareket, kendi kendini konfigüre etme ve bilgi akışı gözetilerek geliştirilmesi yönündedir. Bu araştırma yönelimi beraberinde modüllerin minyatürleştirilmesi gibi sınamalar getirmektedir. Milyon mertebesinde modüle sahip bir KKMR sistemi göz önünde bulundurulduğunda, hareket ve kendi kendini konfigüre etme mekanizmaları için alternatif metotların araştırılması gerekmektedir. Modüllerin dış eyleyiciler ile harekete geçirilmesi mikro KKMR sistemleri için iyi bir seçenek oluşturmaktadır. Bu çalışmada mikro KKMR sistemindeki tekil bir modül için dış manyetik eyleyiciler kullanılarak özgün bir hareket mekanizması geliştirilmiştir. Esnek mikro tüp ve kalıcı mıknatıslardan oluşan bir yapı modülün içerisine yerleştirilmiş ve yapıya periyodik bir hareket uygulanmıştır. Tekil bir mikro tüp kalıcı mıknatıs yapısının hareketi COMSOL Multiphysics yazılımı kullanılarak canlandırılmıştır. Simülasyon sonuçları teorik değerler ile karşılaştırılarak önerilen hareket mekanizmasının doğrulaması gerçekleştirilmiştir.

Most finite element models of small arms focus on an idealized barrel, typically one with a perfectly straight bore centerline. Using five different experimentally measured bore centerlines, this investigation analyzes the effect centerline nonlinearity has on projectile exit conditions. This includes the effect of rotating a centerline through several orientations. Modeled using Abaqus/Explicit, this dynamic analysis simulates a single firing cycle for each centerline. Projectile jump is calculated for each model as a measure of the effects of warped centerlines. The warped centerlines have a small effect on barrel dynamics.

The mortar finite element method is a well-established method for the numerical solution of partial differential equations on domains displaying non-conforming interfaces. The method is known for its application in computational contact mechanics. However, its implementation remains challenging as it relies on geometrical projections and unconventional quadrature rules. The INTERNODES (INTERpolation for NOn-conforming DEcompositionS) method, instead, could overcome the implementation difficulties thanks to flexible interpolation techniques. Moreover, it was shown to be at least as accurate as the mortar method making it a very promising alternative for solving problems in contact mechanics. Unfortunately, in such situations the method requires solving a sequence of ill-conditioned linear systems. In this paper, preconditioning techniques are designed and implemented for the efficient solution of those linear systems.

Humans routinely sit or lean against supporting surfaces and it is important to shape these surfaces to be comfortable and ergonomic. We give a method to design the geometric shape of rigid supporting surfaces to maximize the ergonomics of physically based contact between the surface and a deformable human. We model the soft deformable human using a layer of FEM deformable tissue surrounding a rigid core, with measured realistic elastic material properties, and large-deformation nonlinear analysis. We define a novel cost function to measure the ergonomics of contact between the human and the supporting surface. We give a stable and computationally efficient contact model that is differentiable with respect to the supporting surface shape. This makes it possible to optimize our ergonomic cost function using gradient-based optimizers. Our optimizer produces supporting surfaces superior to prior work on ergonomic shape design. Our examples include furniture, apparel and tools. We also validate our results by scanning a real human subject's foot and optimizing a shoe sole shape to maximize foot contact ergonomics. We 3D-print the optimized shoe sole, measure contact pressure using pressure sensors, and demonstrate that the real unoptimized and optimized pressure distributions qualitatively match those predicted by our simulation.

We present, analyze, and test locally stabilized space–time finite element methods on fully unstructured simplicial space–time meshes for the numerical solution of space–time tracking parabolic optimal control problems with the standard L 2-regularization.We derive a priori discretization error estimates in terms of the local mesh-sizes for shape-regular meshes. The adaptive version is driven by local residual error indicators, or, alternatively, by local error indicators derived from a new functional a posteriori error estimator. The latter provides a guaranteed upper bound of the error, but is more costly than the residual error indicators. We perform numerical tests for benchmark examples having different features. In particular, we consider a discontinuous target in form of a first expanding and then contracting ball in 3d that is fixed in the 4d space– time cylinder.

A sensitivity study is presented to evaluate the influence of different parameters on the simulation of an underground excavation in the Callovo-Oxfordian (COx) argillaceous formation performed in the Meuse/Haute-Marne underground research laboratory. An elasto-viscoplastic constitutive law representing the characteristic behaviour of indurated mudrocks and stiff clays has been employed. It incorporates anisotropy, strain-softening, creep deformations and dependence of permeability on damage. In addition, a non-local formulation, able to simulate localised deformations objectively, has been incorporated in the analyses. The following features affecting the excavation have been studied: initial stress, strength and stiffness anisotropy, strength parameters, hydraulic and hydromechanical parameters, and scale effects. A simulation reported in a companion paper provides the base case for benchmarking. The results are compared in terms of extent and configuration of the excavation fractured zone, vertical and horizontal tunnel convergences, and the development and evolution of pore pressures in the rock. From the comparisons, an enhanced understanding of the hydromechanical mechanisms associated with underground excavations in COx claystone, and other similar argillaceous materials, has been achieved. We are grateful for the financial and technical assistance of the French national radioactive waste management agency (Andra) to the work presented. The technical assistance of Plaxis is also gratefully acknowledged. The first author has been supported by a Conacyt scholarship (Reg. No. 270190).

The performance of plate anchors in sand, relative to clay, is not well understood, particularly for the more realistic case of an inclined load. This paper investigates the effect of load inclination on horizontal plate anchors in sand through centrifuge tests and numerical finite-element simulations. The centrifuge tests were performed on rectangular plate anchors in loose and dense sand, at shallow embedment depths with four different load inclinations. The experiments showed that the anchor capacity of horizontal plates increased progressively as the load inclination became progressively more horizontal, with anchor capacity under pure horizontal loading being approximately 1·8 times higher than that under pure vertical loading. These experimental observations were also replicated in finite-element simulations using a bounding surface plasticity model. Investigation of the underlying failure mechanisms and stress paths showed that the slip planes become longer and the mobilised lateral stresses increase as the load inclination becomes increasingly horizontal, which leads to higher anchor capacities. Finally, the anchor resistance factors from the numerical analyses were decoupled into vertical and horizontal components and represented as interaction diagrams, providing a basis for performing hand calculations of anchor capacity for a given embedment depth, load inclination and relative density.

International audience; In this work, we study theoretically and numerically the equations of Stokes and Navier-Stokes under power law slip boundary condition. We establish existence of a unique solution by using the monotone operators theory for the Stokes equations whereas for the Navier-Stokes equations, we construct the solution by means of Galerkin's approximation combined with some compactness results. Next, we formulate and analyze the finite element approximations associated to these problems. We derive optimal and sub-optimal a priori error estimate for both problems depending how the monotonicity is used. Iterative schemes for solving the nonlinear problems are formulated and convergence is studied. Numerical experiments presented confirm the theoretical findings.

Based on our previous work, we propose a homogenized model of acoustic waves propagating through periodically perforated elastic plates with metamaterial properties due to embedded arrays of soft elastic inclusions serving for resonators. Such structures enable to suppress the acoustic transmission for selected frequency bands. Homogenization of the vibro-acoustic fluid-structure interaction problem in a 3D complex geometry of the transmission layer leads to effective transmission conditions prescribed on the acoustic meta-surface associated with the mid-plane of the Reissner-Mindlin plate. Asymptotic analysis with respect to the layer thickness, proportional to the plate thickness and to the perforation period, yields an implicit Dirichlet-to-Neumann operator defined on the homogenized metasurface. An efficient method is proposed for computing frequency-dependent effective parameters involved in the homogenized model of the layer. These can change their signs, thus modifying the acoustic impedance and the effective mass of the metasurface. The global problem of the acoustic wave propagation in a waveguide fitted with the plate is solved using the finite element method. The homogenized interface allows for a significant reduction of the computational model. Numerical illustrations are presented.

This paper deals with, in the framework of absolute stability, boundary stabilization for a nonlinear axially moving beam under boundary velocity feedback controls. The nonlinear boundary control that satisfies a slope-sector condition covering many types of nonlinear control schemes is a negative feedback of the transverse velocity at the right eyelet of the moving beam. Under the nonlinear control scheme, the well-posedness of the nonlinear partial differential equation which depends continuously on the initial value is investigated by means of the Faedo-Galerkin approximation and priori estimates. By exploiting the integral-type multiplier method, the exponential stability of the closed-loop system is established, where a novel energy like function is constructed. The numerical simulation examples using the finite element method are presented to illustrate the effectiveness of the established criterion of the controller.

Considering the influence of iron core saturation and complex boundary conditions, a novel no-load magnetic field analytical method and system multi-objective optimization model for interior permanent magnet synchronous motor (IPMSM) are proposed. Firstly, an analytical method based on magnetic potential permeance method is proposed. The complex cogging effect and equivalent air gap permeability function are fully considered in this method. Furthermore, on the basis of Taguchi optimization design based on Fuzzy theory, an improved optimization model considering multi-variable interaction is proposed. Among them, in order to comprehensively consider the performance of electromagnetic, vibration, and temperature rise, five optimization objectives including torque, pulsation, cogging torque, loss, and flux density have been optimized. The sensitivity of design variables and the interaction between variables are not ignored. Finally, a 6-pole 36-slot IPMSM is manufactured for prototype experiments. A large number of prototype experiments, finite element, and computational fluid dynamics simulation analysis including no-load magnetic field, back electromotive force, temperature rise, electromagnetic torque, and so on are carried out. The accuracy and rationality of the proposed no-load magnetic field analysis method and global optimization model have been well verified.

This paper presents a new interior permanent magnet (IPM) rotor structure/ assembly which inherits from the Halbach magnet configuration and spoke-type IPM rotor to achieve a high saliency ratio and high torque/power density. A higher air-gap flux density and a higher saliency ratio are expected to improve torque density, while the rotor inner diameter can be maximized as much as possible to reduce core material consumption and increase internal space of the rotor. Accordingly, the electromagnetic performance of three motors consists of a unified stator but three different rotors, namely flux-concentrating rotor, Halbach array PM rotor and spoke-type IPM rotor is compared by finite element analysis (FEA). Due to the segmented structure of flux-concentrating PM rotor without magnetic bridges, the mechanical challenges are analyzed in detail for electric vehicle application. The stress analysis on the prototype design with fixing pins to hold the pole pieces validates the structural feasibility at 7200 r/min. Finally, a 72-slot/ 16-pole fractional-slot PM motor with new flux-concentrating rotor is manufactured and tested to verify its performance and feasibility. It can be concluded that the new rotor is superior to the spoke-type IPM and Halbach array PM rotor in terms of torque density and PM utilization.

Based on thermoelectric analogy method, a thermal network model coupled with electromagnetic loss is presented. According to the actual structure of dry-type transformer windings, an accurate thermal network is established. Considering the distribution characteristics of heat source along cooling ducts inside the dry-type transformer, the thermal parameters such as heat flux and convective heat transfer coefficients are calculated by finite element method analysis (FEM) and computational fluid dynamics (CFD). Based on temperature rise experiment, the hottest spot located at the top of outmost high voltage winding is 151.8 °C, which verified the correctness of thermal network model.

In this research paper, focusing on the basic variables of the gear modeling process and setting its dimensions to see which gears are capable of withstanding transmission operations and its rigidity was done. Because one of the most prominent transmission mechanics is gears, as the types of gears are numerous and common, and one of the most prominent types of gears is the helical gear. The helical gear is one of the most widely used and widespread gears in mechanical fields due to the increase in the contact area during the interlock process, as this increase reduces noise during gear rotation. Three main variables were used to establish the results. The first of which is the pressure angle, the helix deflection angle, and the module number, and they made a number of cases to see which one was able to withstand the movement operations with a proven torque. The results proved that the distortion value in the first case at module 1 was 87×10-6 m, while in module 2 the distortion value was 3.75×10-6. The data are useful and important because the values of the stresses that affect the gears must be known by changing the module due to it gives a stronger concept of the extent to which the gears can withstand movement. Pressure angle is one of the basic variables that change the dimensions of wind turbine gears. The value of the greatest stress was 2.13×108 Pa, but at the pressure angle of 20 degrees, the stress value was 1.93×108 Pa. It affects the diameter, stiffness and tensile strength of a wind turbine. The study of this research paper depends on helical gears. It is known that the angles of the helical teeth increase the large contact area between two gears. From the resulting deformation values, it is noted that the deformation value is 4.26×10-6 m when the helix angle is 20 degrees., У цій дослідницькій роботі основна увага приділялася основним змінним процесу моделювання зубчастих коліс та налаштуванню його розмірів, щоб встановити, які зубчасті колеса здатні витримувати операції трансмісії, та їх жорсткість. Одним з найвідоміших механізмів трансмісії є зубчасті колеса, так як типи зубчастих коліс численні і поширені, а одним з найвідоміших типів зубчастих коліс є косозуба шестерня. Косозуба передача є однією з найбільш широко використовуваних і поширених передач в області механіки через збільшення площі контакту в процесі блокування, так як збільшення знижує шум при обертанні шестерні. Для отримання результатів використовувалися три основні змінні: кут тиску, кут відхилення спіралі і номер модуля, і досліджувалося, який з них здатний витримати операції переміщення з перевіреним крутним моментом. Результати показали, що величина спотворення у першому випадку на модулі 1 склала 87×10­6 м, а на модулі 2 значення спотворення становило 3,75×10­6. Дані корисні і важливі, тому що значення напруги, що впливають на шестірні, повинні бути відомі шляхом зміни модуля, оскільки це дає більш чітке уявлення про те, як шестірні можуть витримувати рух. Кут тиску є однією із основних змінних, які змінюють розміри зубчастих коліс вітряних турбін. Значення найбільшої напруги становило 2,13×108 Па, але за за дією тиску при значенні кута 20 градусів значення напруги становило 1,93×108 Па. Воно впливає на діаметр, жорсткість та межу міцності вітродвигуна. Використання результатів, отриманих в цій роботі, залежить від косозубих передач. Відомо, що кути гвинтових зубів збільшують велику площу контакту між двома шестернями. З отриманих значень деформації видно, що значення деформації становить 4,26×10­6 м при куті нахилу спіралі 20 градусів

Train passages over intact or damaged slab tracks on different soils were calculated by two methods. The finite element method (FEM) uses a Winkler soil under the track model by adding a thin “soil layer”. The combined finite-element boundary-element method has a continuous soil model that is included by the boundary element method. The basic results are the distributions of the track (rail, track plate, and base layer) displacements along the track for a single axle load. These solutions were superposed to a complete train load and transformed to time histories. The influence of track and soil parameters was analysed. The main interest was the influence of the track damage. A gap between the track plate and base layer of different lengths was studied for changes in amplitudes and widths of deflection. A best fit to measured track displacements was found so that the track damage could be identified and quantified. The FEM model with the Winkler soil cannot be fitted to the amplitude and width with the same soil parameters. Therefore, the FEBEM model is preferable for these railway track problems.

The study of the structural elements goes through the premise of their centric support and centric connection. In reality, it is common to see elements with different cross-sections connected by offset axes, for example to align some of their edges, or those that are supported with off-center supports. Such inter-element eccentricities and off-center supports leads to a change in the stress-strain state from the traditional ones known from the available literature and university textbooks. In previous publications with participation of the author, exact nonlinear and approximate analytic solutions of similar problems for beams under various loading, support and connection conditions have already been published. The finite element method provides an approximate approach for computer analysis. In this paper, results obtained through a computer program created in the MATLAB, based on a finite element accounting for eccentricity in connection and off-centering of support, are demonstrated. The results shows values in the diagrams of internal forces differing by up to 15-30% compared to the classical theory of centric connection and centric supporting.

Malang Indonesia is an area prone to landslides, resulting in the need to model soil reinforcement to determine the vegetation’s slope stability using the roots of five species. One of the methods to improve the stability of slopes prone to landslides is adequate vegetation preservation. Soil strengthening with vegetation roots is environmentally friendly and an inexpensive alternative to reduce the vulnerability of slopes along mountainous slopes and the risk of shallow erosions. Therefore, this study aims to evaluate the vegetation arrangement on the slopes in Malang Regency, Indonesia, with a view of geotechnical engineering on the role of its root characteristics. Slope stability was analyzed by modeling the distribution of vegetation roots as an equivalent cohesion approach, where the factor of safety (FoS) is calculated using the PLAXIS-2D version 86 software. Soil and root parameters were obtained through direct shear testing and examining five plant species’ tensile strength. The results showed that the highest stability is achieved when the position of the vegetation on the slope’s surface is compared to the top. The factor of safety (FoS) increased from 23% to 30% and from 28% to 31% for slopes with uniform and combined species. Of the five plant species, P. merkusii demonstrated some advantages in maintaining stability because it has better root mechanical properties, among others. However, the combined species, such as C. arabica, had better performance because they possess vertical and lateral root systems, which act as an anchor in penetrating and griping the soil. This means combining vegetation species is a preferable preventive measure to increase slope stability. The analysis results also demonstrated the significance of vegetation on slope stability. The results show that the FoS decreases when the slope angle increases and reaches its maximum when the species are combined. The mechanical effect of the plant root matrix system can increase the shear strength of the soil, thereby raising the slope stability. The density of roots in the soil mass and the tensile strength contribute to the soil’s ability to withstand shear stresses.

The electrical contact status between metal layers in a Press Pack Injection Enhanced Gate Transistor (PP-IEGT) is essential information for the reliability of the whole device. This paper employs the numerical method, microscopic detection, and power cycle test (PCT) to qualify the contact degradations and performance in PP-IEGT. Firstly, the contact status of metal pair aluminum-molybdenum in a single-chip module is described through the finite element method (FEM). Then, the contact fatigue of the single-chip module is estimated by the micro-detection of chip surface and the monitor of contact resistance during PCT. Finally, PCTs are conducted on parallel branches to explore the contact degradation under different contact statuses. The results show that the chip is subjected to fretting wear and cracks due to the periodic expansion and shrink. In the aging process, the contact resistances display a linear growth trend and have a significant impact on the electrical parameter shift. Moreover, the degradation of the branch with insufficient contact is more serious, especially under smaller clamping force and longer heating duration.

Stiffened panels have been widely utilized in fuselages and wings as critical load-bearing components. These structures are prone to be damaged under long-term and extreme loads, and their health monitoring has been a common concern. The guided wave-based monitoring method is regarded as an efficient approach to detect the damage in stiffened plates because of its wide monitoring range and high sensitivity to micro-damage. Efficient simulation of wave propagation can theoretically demonstrate the detection mechanism of the method. In this study, a Time-Domain Spectral Finite Element Method (TD-SFEM) is adopted to study the wavefield in stiffened plates, where continuous Absorbing Layers with Increasing Damping (ALID) strategy is proposed to circumvent the disturbance of reflected waves on boundaries. After the convergence analysis, the developed TD-SFEM with ALID is validated by the finite element method first. Then, wave scattering and the influence of the stiffener are investigated in detail by comparing the results with the non-stiffened structure. Finally, the effects of the parameters of the stiffener, such as the height and width, on wave propagation are studied, respectively. The results illustrate that the proposed TD-SFEM with ALID is an efficient approach to study the wave propagation in the stiffened plate and can reveal the mechanism of influence of the stiffener. It is found that the height of the stiffener changes the interference of wavefield in the plate, while the effects of the width are mainly in wave scattering and mode conversion.

This work reports on a soft gripper with three-dimensional (3D) printed soft monolithic fingers that seamlessly incorporate pneumatic touch sensing chambers (pTSCs) for real-time pressure/force control to grasp objects with varying stiffness (i.e., soft, compliant, and rigid objects). The fingers of the soft gripper were 3D printed simultaneously along with the pTSC, without requiring support materials, using an inexpensive fused deposition modeling 3D printer. The pTSCs embedded in the fingers have numerous advantages, including fast response, repeatability, reliability, negligible hysteresis, stability over time, durability, and very low power consumption. Finite element modeling is used to predict the behavior of the pTSCs under different body contacts and to design their topology. Real-time pressure/force control was performed experimentally based on the feedback data provided by the pTSCs to grasp various objects with different weights, shapes, sizes, textures, and stiffnesses using an experimentally tuned proportional-integral-derivative (PID) controller with the same gains for all the objects grasped. In other words, the gripper can self-adapt to different environments with different stiffnesses and provide stable contact and grasping. These results are validated theoretically by modeling the soft gripper in contact with the objects with varying stiffness to show that the stability of the contact motion is not affected by the stiffness of the environment (i.e., the grasped object) when constant PID control gains are used.

In this article, we introduce a framework for the geometric design and fabrication of a family of geometrically interlocking space-filling shapes, which we call woven tiles. Our framework is based on a unique combination of (1) Voronoi partitioning of space using curve segments as the Voronoi sites and (2) the design of these curve segments based on weave patterns closed under symmetry operations. The underlying weave geometry provides an interlocking property to the tiles and the closure property under symmetry operations ensure single tile can fill space. In order to demonstrate this general framework, we focus on specific symmetry operations induced by fabric weaving patterns. We specifically showcase the design and fabrication of woven tiles on flat and curved domains by using the most common 2-fold fabrics, namely, plain, twill, and satin weaves. We further evaluate and compare the mechanical behavior of the so created woven tiles through finite element analysis.

This article reports on the design, modeling, control, and testing of a novel compliant nanopositioning stage driven by a self-developed normal-stressed electromagnetic actuator. To facilitate the parameter selection for the stage to achieve the desired stroke and natural frequency, an analytical model of both the electromagnetic circuit and flexure mechanism is established, which is then systematically verified through finite element analysis. By combining a proportional--integral--differential (PID)-based main controller with a system dynamics inversion-based feedforward compensator, a closed-loop control system for the stage is constructed with the main controller being tuned through Bode's ideal transfer function-based loop-shaping method. The experimental result shows that a stroke of ± 95 μ m and a first natural frequency of 743 Hz are achieved for the designed stage. Finally, taking advantage of the constructed control system, the nanopositioning capability is demonstrated by finely tracking the harmonic and nanostair commands.

International audience; Thermal-hydraulics safety requirements for the second and third generation of nuclear reactors led to the development of innovative passive safety systems. In particular, new devices must be developed involving numerical simulations for turbulent two-phase flows around complex geometries. To reduce the time-consuming mesh generation phase when testing various geometries, we use a fictitious domain approach. More specifically, we choose the Penalized Direct Forcing Method to take into account inflow obstacles. Following a recent work, involving the resolution of the one-phase incompressible Navier-Stokes equations using a projection scheme and the Finite Element Method, this paper focuses on different techniques to recover data from the discrete immersed boundary and different ways to achieve order 2 in space via linear interpolation. Indeed, we investigate two data reconstruction approaches (one based on various weighted averaging, the other based on optimization) and compare their results for cylindrical and NACA0012 airfoil shapes: they provide similar accuracy but the weighting is much faster in terms of execution time. We also investigate three different interpolation types: unidirectional, multi-directional and a new hybrid between the two. The Taylor-Couette flow and the flow around a circular cylinder are used to carry out mesh convergence studies. Globally, order 2 in space is numerically assessed in both  2 and  ∞ norms for all the interpolation types, which is consistent with theoretical expectations-even if the space convergence order is a bit higher for the multi-directional approach. For the flow around a circular cylinder, the values of aerodynamic coefficients and Strouhal number are in good agreement with the literature, especially when using directional interpolation. Finally, an industrial case, representative of passive safety systems, is presented to assess the robustness and capability of the method. The simulations tend to show that, here again, the directional interpolation offers the best behavior when dealing with complex geometries and relatively coarse meshes.

Various kinds of implants of different diameters and connection types are used for patients with a range of bone densities and tooth sizes. However, comprehensive studies simultaneously analyzing the biomechanical effects of different diameters, connection types, and bone densities are scarce.The purpose of this 3-dimensional finite element analysis study was to evaluate the stress and strain distribution on implants, abutments, and surrounding bones depending on different diameters, connection types, and bone densities.Twelve 3-dimensional models of the implant, restoration, and surrounding bone were simulated in the mandibular first molar region, including 2 bone densities (low, high), 2 implant-abutment connection types (internal tissue level, internal bone level), and 3 implant diameters (3.5 mm, 4.0 mm, and 4.5 mm). The occlusal force was 200 N axially and 100 N obliquely. Statistical analysis was performed using the general linear model univariate procedure with partial eta squared (ηFor bone tissue, low-density bone induced a larger maximum and minimum principal strain (in magnitude) than high-density bone (P.001). As the implant diameter increased, the volume of the cancellous bone in low-density bone at the atrophy region (strain200 με) increased (P.001). For implant and abutment, the internal bone-level connection type was associated with increased peak stress as compared with the tissue-level connection type (P.001). For all models, the stress distribution on the implant complex was influenced by implant diameter (P.001): a decrease in implant diameter increased the stress concentration.The implant connection type had a greater impact on the stress of the implant and abutment than the diameter. A tissue-level connection was more advantageous than a bone-level connection in terms of stress distribution of the implant and abutment. Bone density was the most influential factor on bone strain. The selection of dental implants should be made considering these factors and other important factors including tooth size.

Objectives This study aims to evaluate the fatigue stress around custom-made all-on-4 implants system to find out which type of implants have a better performance under different graded multidirectional occlusal forces. Material and methods 3D normal and implanted models simulating the “All-on-4” concept were created and analyzed under three different conditions of occlusal loadings. Two types of static and fatigue were applied. Stress distribution was analyzed based on von Mises and Goodman theories in ANSYS environment in addition to the safety factor. Statistical tests were performed to assess the significance of the results as well as the reproducibility of the results. Results The results showed stress increasing reaching a value of 48%, 29% in tilted implants compared to vertical implants and normal cases respectively. In contrast, tilted implants appeared to be less stable (safety factor may reach 0.7) and they may fail during the application of occlusal forces. The safety factor of cortical bone decreased by about 91% in the implanted model compared to the normal model, indicating a higher possibility of bone remodeling around the bone. Conclusion The orientation and position of occlusal forces had an important influence on stress distribution between the implant and the surrounding bone, and fatigue loading caused greater stresses in comparison with static loading. Lower amounts of stress were found in the vertical implants, ensuring a higher safety factor and a longer clinical service. In contrast, the critical safety factor values are observed in tilted implants, which may fail under the influence of applied occlusal forces.

This article presents the design and performance of a small-scale magnetorheological (MR) brake, with the fastest time constant and highest torque-to-mass ratio among small-scale MR brakes (i.e., those with a diameter less than 40 mm and a thickness less than 30 mm), which are typically designed for use in small haptic or robotic devices. By combining disk- and drum-type designs and incorporating the current-carrying coils into the rotor, this brake uses all three shear surfaces of the rotor to generate large braking torque. Additionally, a serpentine magnetic flux path that crosses the MR fluid shear surfaces a total of six times is used to achieve this torque in a small form factor. An FEM model is used to inform the dimensions of the brake components to increase the magnetic flux density within the MR fluid gap. This enables us to increase the shear force of the MR fluid, and thus, increase braking torque. To characterize brake performance and dynamic response, we measure the relationship between current and braking torque. We then compare the brake’s performance to various types of similarly sized commercial brakes and other small-scale MR brakes found in the literature.

In this study, the dynamic effect of stator turn-to-turn short-circuit fault on electrical, mechanical and magnetic motor parameters is investigated in detail. For this purpose, the Finite Element Method (FEM) based ANSYS@Maxwell-2D program is used, which enables steady state and transient analysis. The changes in stator current and induced back electromotive force voltage from electrical parameters, output torque from mechanical variables and leakage flux from magnetic parameters are examined in detail in both time and frequency axis by means of Fast Fourier Transform (FFT) for the faulty state. Moreover, in order to detect stator turn-to-turn fault, stray flux analysis is carried out and characteristics fault signatures are defined. The obtained results and findings have been proven through the developed experimental setup in laboratuvary., Bu çalışmada asenkron motorlarda yaygın olarak görülen stator sarım-sarım arası kısa devre arızasının elektriksel, mekaniksel ve manyetiksel motor parametrlerine dinamik etkisi detaylı olarak incelenmiştir. Bu amaçla kalıcı ve geçici durum analizlerinin yapılabilmesine imkan sağlayan Sonlu Elemanlar Yöntemi (Finite Element Method-FEM) tabanlı ANSYS@Maxwell-2D programından yararlanılmıştır. Öncelikle 2.2 kW anma gücüne sahip bir asenkron motor modellenerek bu model üzerinde sağlıklı durum verileri toplanmıştır. Daha sonra farklı seviyelerde stator sarım-sarım arası kısa devre arızaları oluşturularak arızalı durumda belirlenen motor parametrelerinin değişimi ve karakteristik arıza sinyalleri incelenmiştir. Arızalı durumda Hızlı Fourier Dönüşümü (Fast Fourier Transform-FFT) aracılığıyla elektriksel parametrelerden stator akımı ve indüklenen ters elektromotor kuvvet gerilimi, mekaniksel büyüklüklerden çıkış momenti ve manyetiksel parametrelerden kaçak akıdaki değişimler hem zaman hemde frekans ekseninde detaylı olarak incelenmiştir. Ayrıca stator sarım sarım arızasını tespit etmek için kaçak akı analizi yapılmış ve karakteristik arıza sinyalleri belirlenmiştir. Elde edilen bulgular laboratuvar ortamında oluşturulan devre düzeneği ile doğrulanmıştır.

In the present work, we focus on the resolution of the Cauchy Laplace problem using an energetic variational minimization approach [18] in the framework of a finite element method. A new strategy of regularization, called a filtering procedure regularization, is developed. The advantage of using this new regularization is that it does not require a regularization parameter and is easy to implement. An optimal a priori error estimate is proven, for the first time up to our knowledge, in the context of the finite element method. Some numerical results are presented to illustrate the performance of our approach.

In modeling fluid–solid interaction (FSI), considering the impact of fluid compressibility is necessary to describe sound propagation. Furthermore, in micro-scale, fluid viscosity is important. We present a finite element formulation for modeling a flexible solid coupled to a compressible viscous fluid. We use the linearized Navier–Stokes equations for a Newtonian fluid and describe the linear elastic solid using the linearized balance of momentum. For coupling between fluid and solid, we develop a non-conforming finite element formulation, and propose an estimation for the necessary penalty factor by applying a scaling approach. The formulation is validated based on several test cases for various material combinations and shows good agreement with analytical solutions. Further, Nitsche-based and symmetrization-free formulations are compared, and spatial convergence is studied. Finally, we present an application example of a miniature Helmholtz resonator, which depicts a notable impact of the solid interaction on the viscous flow. In sum, our study indicates the potential for widespread use of the presented numerical approach in modeling FSI in miniature systems.

The aim of this paper is to put on display the numerical solutions and dynamics of time fractional Fitzhugh-Nagumo model, which is an important nonlinear reaction-diffusion equation. For this purpose, finite element method based on trigonometric cubic B-splines are used to obtain numerical solutions of the model. In this model, the derivative which is fractional order is taken in terms of Caputo. Thus, time dicretization is made using L1L1 algorithm for Caputo derivative and space discretization is made using trigonometric cubic B- spline basis. Also, the non-linear term in the model is linearized by the Rubin Graves type linearization. The error norms are calculated for measuring the accuracy of the finite element method. The comparison of numerical and exact solutions are exhibited via tables and graphics.

In this work, a finite element formulation for a size dependent frame system is presented. Size dependency is discussed via the modified couple stress theory. The nodal displacement and rotation analyses of a frame system with total of three elements, including two columns and one beam element connecting these two columns, are considered. The classical stiffness and size dependent stiffness matrices of frame system are derived. Then, solution procedure for this problem is explained. Lastly, a numerical application is realized and effect of material length scale parameter on nodal displacements and rotations is discussed. To present the numerical application, it is assumed that the elements of the nanoframe are composed of silicon carbide nanotubes.

The selection of appropriate geometrical characteristics of enclosure has salient influence on performance of different thermal engineering processes and devices like microelectronics, heat exchangers, power engines, boilers, solar collectors, nuclear reactors and so forth. Specifically, the triangular cavity of different aspect ratios are used to obtain multi-objective optimization and gaining excellence in thermal performance of micro channels. Subsequently, the installation of cold cylinder in a triangular enclosure are extensively used to remove high energy dissipation in micro heat sinks and heat exchangers. So, the purpose of current effort is to probe thermal characteristics of power-law liquid describing features of shear thinning and thickening materials containing applications in lubrication and polymer industry. Heat transfer is generated by the consideration of natural convection process generated due to consideration of cold walls and cylinder with provision of non-uniform heating at base wall. No-slip velocity conditions are supposed at all walls of isosceles triangle cavity. Solution of attained differential system is simulated by capitalizing finite element based COMSOL Multiphysics software (Version 5.6). Domain discretization by distributing into triangular and rectangular elements is conceded and equations at element levels are discretized by executing weak formulation. The validation of adopted numerical procedure is established by making agreement with formerly available works in both statistical and graphical approaches. Streamlines and isotherms are plotted and discussed against various parametric regimes. This study reveals noticeable influence of involved physical parameters on average and local heat flux coefficients, kinetic energy and cutlines against involved physical parameters are also evaluated. It is inferred thorough the analysis that with uplift in Rayleigh number (Ra) produces enrichment in kinetic energy and local heat transfer coefficients whereas reverse pattern is depicted against power-law index.(n).

Permanent magnet synchronous motors (PMSMs) with non-concentric magnetic poles (NCMP) structure are widely used as high-precision servo motors. The current subdomain method mainly equates the NCMP to a rectangular magnet to make each subdomain boundaries of magnet parallel when calculating the magnet eddy current loss (ECL), which results in a lower accuracy of the calculation. This paper divides the NCMP into non-concentric region and concentric region along the radial direction. The non-concentric region is further divided along the circumferential direction, and each divided region has a single thickness. Based on the subdomain method, a novel analytical method of magnet ECL in PMSMs with NCMPs is proposed. Moreover, the 3-D distribution coefficient of ECL in the NCMP is derived by the equivalent impedance method. The effects of eddy current reaction and stator slotting are taken into account to improve the calculation accuracy. Then, through theoretical derivation, the relationship between the minimum magnet loss and the pole parameters is obtained, which provides a reference for the design of NCMPs. Finally, the loss separation experiment is performed on four prototypes with NCMPs. The experimental results, finite element method results and analytical results are compared to verify the correctness of the model.