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• A multi-field coupling model and simulation platform are based on COMSOL5.3. • The effects of process parameters and reactor structure on coating silicon nitride film are studied concurrently. • Transforming dynamic coating problems into static problems for simulation research. This paper builds a physical model by using the finite element method on COMSOL simulation platform to simulate the in-line PECVD process. The in-line PECVD simulation model couples the flow field, thermal field, chemical reaction field and plasma field and is verified through experiments. In addition, a new simulation strategy is proposed to solve the problem of dynamic coating silicon nitride film. Through this simulation method, process parameters and structural parameters of the in-line PECVD equipment are optimized. Effects of microwave tube position, microwave shield size, total gas flow, pressure and temperature on main coating reaction region is studied. The results have shown that the position of microwave tube, the total gas flow and temperature have greater influence on the region of reaction zone, the concentration distribution of reactants and the thickness of SiN x H y film. Through optimizing process parameters and structural parameters, the coating rate of SiN x H y film can be increased from 0.0607 nm/s to 0.15 nm/s and the deposition thickness can be increased from 6.78 nm to 15.59 nm. The molar concentration of SiN x H y particles in the reaction region has grown by more than 23.5%. And the relative intensity of reaction field inside PECVD chamber has increased by 1.3–2.3, which is calculated by molar concentration ratio of SiN x H y particles. This paper provides a reference for the optimization of in-line PECVD equipment. [ABSTRACT FROM AUTHOR]

The calculation of the temperature fields in solid state transformers is a critical step of the design process in order to ensure the stable and efficient operation of the device. Transformers operating in high frequencies can develop increased temperatures that potentially may result in the failure of the components due to the associated thermal stresses. This paper investigates the heat transfer mechanisms of a novel inductive power transfer (IPT) system submerged in a dielectric oil and operating at 50 kHz, in the context of SSTAR, a Horizon Europe project. The commercial software ANSYS is employed to implement a one-way coupled electromagnetic-thermal finite element simulation model in order to calculate the temperature field of the IPT components based on the electromagnetic losses. To cross-validate the model, the results obtained from ANSYS are benchmarked against the COMSOL software, revealing accepted temperature deviations between the two software. A comprehensive parametric analysis explores the impact of rated power, operating frequency, and dielectric gap on generated heat, highlighting their direct correlation with temperature increase. The findings underscore increased temperature levels, approximately reaching 224 °C under nominal operating conditions, with the temperature distribution concentrated around the transformer's windings. • Design of a novel high frequency 50 kHz Inductive Power Transfer system. • Assessment of the heat transfer mechanism of an Inductive Power Transfer system. • Development of a comprehensive coupled electromagnetic-thermal simulation model and validation. • Parametric analysis on the effect of rated power, frequency and dielectric gap on power loss and temperature. [ABSTRACT FROM AUTHOR]

A high-pressure chamber is the main equipment required for simulating deep-sea operational environment and used for evaluating the performances of underwater equipment such as underwater vehicles under a preset pressure so that the possible malfunctions could be alarmed before deep-sea commissioning. In this paper, due to its current unavailability, a high-pressure chamber with the maximum working pressure of 60 MPa was designed, which has the inner diameter of 3 m and the height of 4 m, possesses the video transmission function and allows most of the small-scale underwater vehicle's overall stability and capacity to be tested possible. To tackle the leakage and ensure the stability of the chamber, this paper proposes a novel sealing method, which adopts the combination of anti-shear block device and four O-ring seals and has the advantage of no need of manual pre-tightening and of sufficient shear resistance. The performance and strength analysis of the chamber were carried out by Ansys/Workbench finite element analysis software. Furthermore, The high-pressure chamber was manufactured and its experiment verification results indicate that with larger containment volume and more advanced control system it could work reliably, which made it feasible for its engineering application. • A high-pressure chamber is the main equipment required for simulating deep-sea operational environment. • With the maximum working pressure 60 MPa, the high-pressure chamber has the inner diameter of 3 m, the height of 4 m. • The chamber possesses the video transmission function. • The performance and strength analysis of the high-pressure chamber were carried out by Ansys/Workbench FEA.. • Both the simulation and the experiment show that the chamber works reliably and is feasible for engineering application [ABSTRACT FROM AUTHOR]

Abstract Terrestrial laser scanning is extensively adopted in the area of high-precision monitoring and three-dimensional measurement. Architectural structures today are increasingly complex and health monitoring plays an important role in guaranteeing their safety. Therefore, how reliability deformation monitoring can be improved is one of the key problems in the field of engineering. This paper combines the three-dimensional laser scanning technology and finite element method (FEM) to investigate the deformation mechanism of arched structures. Within this paper, we simulated arched structures using the FEM, which is consistent with the result of terrestrial laser scanner (TLS) measurement. We aimed at constructing an intelligent and efficient FEM model which can be extensively applied in the monitoring of many constructs, such as bridges and ancient architecture. The focus in this research lies mainly on deformation analysis, which is based on FEM model simulation with the calibration of TLS measurement. [ABSTRACT FROM AUTHOR]

Highlights • Both macrocrack and microcrack growth simulations by using the extended finite element method (XFEM) are presented. • The formulations of three typical frameworks of the XFEM are introduced. • The simulations of brittle and ductile crack growth under monotonic and cyclic loadings are demonstrated. • The outlook of the XFEM on crack growth simulations is pointed out. Abstract During the latest 20 years, the extended finite element method (XFEM) has been gradually used to investigate the crack growth behaviors of different materials in combination with various mechanics models and became the most popular computational tool in analyzing crack problems. This paper classifies three typical theoretical frameworks of the XFEM, namely the linear elastic fracture mechanics, the cohesive zone model and the elastic-plastic fracture mechanics based XFEM. A review of brittle and ductile crack growth under both monotonic and cyclic loadings using the XFEM was given from both macro-scale and micro-scale after a systematic literature survey. In contrast, the framework of the XFEM for modeling brittle fracture is the most comprehensive and widely used theory, but the theory for the ductile crack growth has still to be developed. Additionally, the XFEM becomes more complicated in microcrack growth simulations than macrocrack by considering the effects of microstructures of materials. The XFEM can introduce an arbitrary discontinuity into the finite element and can be employed to analyze different crack growth problems in engineering materials and structures, this paper is served as a valuable reference for the future study in this field. [ABSTRACT FROM AUTHOR]

The numerical modelling of the internal heat generation in passenger vehicle tyres using finite element analysis is a well-known numerical approach. However, this application is rather uncommon for earthmover tyres. This paper describes the development of a finite element model of a 23.5R25 earthmover tyre for the numerical modelling of the temperature distribution in the tyre cross-section at steady-state heat transfer conditions using an uncoupled analysis procedure. Considering the non-linear behaviour of the rubber compounds used for the manufacturing of these tyres, as well as the complexity associated with the composite structural aspects of the tyre, the material properties used for the proposed numerical model were established experimentally. In the analyses completed, the tyre behaviour was studied by simulations at various inflation pressures, loads and rolling velocities. The numerical tyre defection was within an 8% deviation from the actual tyre behaviour. Thermal simulation results were used to derive an equation that can be used to predict the maximum temperature that would occur in the tyre’s cross-section as a function of its vertical deflection, its forward rolling velocity and the ambient temperature of the surroundings. The numerical models and simulations presented in this paper were completed using MSC.Marc/Mentat. [ABSTRACT FROM AUTHOR]

This paper proposes a computerized approach based on the influence coefficient method to solve the statically indeterminate problem of multiple loaded contact tooth pairs in planetary gear drives. The influences of the deformation on the loaded contact characteristics are divided into three categories according to the relation of the acting load and the deformation on the specific tooth pairs, the gears and the gear pairs, respectively. Not only the contact and bending deformation of the engaged teeth, but also the planet shaft deflection and the twist deformation of the carrier and the sun gear are involved in the model. With discretized contact region of each tooth pair, three-dimensional contact patterns with distributed stresses, including the concentrated stress due to edge effect and tip corner contact, can be simulated. The simulated results are verified to have a good agreement with FEM. A numerical example of a planetary gear set with non-modified flanks and the error-free condition is analyzed in the paper. The effects of the deformation, the variations of the shared loads, the contact stress, the loaded transmission errors, and the contact patterns with the distributed contact stresses in the cases with/without tip corner contact are discussed. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of the transient contact solutions of wheel-rail frictional rolling impacts calculated by an explicit finite element model of the wheel-insulated rail joint (IRJ) dynamic interaction. The ability of the model to simulate the dynamic behavior of an IRJ has been validated against a comprehensive field measurement in a recent paper (Yang et al., 2018). In addition to the measured railhead geometry and bi-linear elastoplastic material model used in Yang et al. (2018), this study adopts a nominal railhead geometry and an elastic material model for the simulations to provide an overall understanding of the transient contact behavior of wheel-IRJ impacts. Each simulation calculates the evolution of the contact patch area, stress magnitude and direction, micro-slip distribution, and railhead nodal vibration velocity in the vicinity of the joint during the wheel-IRJ impacts. The simulations apply small computational and output time steps to capture the high-frequency dynamic effects at the wheel-IRJ impact contact. Regular wave patterns that indicate wave generation, propagation and reflection are produced by the simulations; this has rarely been reported in previous research. The simulated waves reflect continuum vibrations excited by wheel-rail frictional rolling and indicate that the simulated impact contact solutions are reliable. [ABSTRACT FROM AUTHOR]

In this paper we consider the simulation of the dynamic behaviour of deep drawn components by means of the finite element method (FEM). The deep drawing process involves high deformations which result in an irregular thickness distribution in the manufactured component. The thickness variation therefore has to be taken into account in the dynamic FEM simulation, since a reference model based on the initial thickness of the blank material often fails to accurately represent the dynamic properties of the final component. In order to properly account for this variation, two approaches are considered in this paper: the first one consists in simulating the forming procedure with the FEM and subsequently using the resulting geometry for the dynamic analysis. The second approach consists in the generation of an FEM model for the dynamic analysis starting from laser scan measurements on the manufactured component. Both approaches are analysed in detail and are validated with experimental measurements. It is found that the framework based on surface measurements provides slightly more accurate results but the purely numerical procedure is still a useful and faster methodology to obtain engineering accuracy. [ABSTRACT FROM AUTHOR]

In this paper, a novel numerical simulation approach based on the finite element method for dynamically modeling the excavation process of shield tunneling is proposed, with the shield-ground interactions well captured. This method is capable of mimicking the alternating modes of advancing and stopping of a shield boring machine during underground construction, with the important effects of the cutterhead rotation and slurry support pressure considered. Under the cutting action, the soil at the excavation face would experience irreversible deformation and damage, such that additional support needs to be provided by the cutterhead blades and slurry to maintain stability. The impacts of key construction parameters are examined, including cutterhead rotary speed, advance rate, and slurry support pressure, on shield tunneling operations and ground responses. The numerical model is rigorously validated against physical model experiments. This work provides useful insights into the mechanistic processes in the stratum during shield tunneling, including the spatiotemporal evolution of ground deformation patterns and stress redistributions. The results offer valuable guidance for optimizing shield tunneling operations and enhancing tunneling safety and efficiency. [ABSTRACT FROM AUTHOR]

The present paper focuses on the discretization and implementation of the Thick Level Set (TLS) approach for quasi-brittle failure when dealing with both local and non-local development of damage. The TLS damage model introduces a length scale and nonlocality in the Fracture Process Zone (FPZ) and it handles the continuous to discontinuous failure transition. The added nonlocality is limited to the FPZ and therefore the model is local away from the FPZ or before its emergence. It leads to concurrent development of local and nonlocal damage during simulations. This paper presents a space–time discretization that handles concurrent computations in a unified manner. It is based on an explicit time discretization written as a predictor–corrector scheme and a space discretization that uses specific approximation functions (modes) that embed nonlocality. It also uses an alternative implementation of the eXtended Finite Element Method (X-FEM) enrichment used in the TLS which is based on virtual nodes. [ABSTRACT FROM AUTHOR]

Pulsed water jets have been widely applied in the field of underground mining because of their unique advantages. Revealing the mechanical mechanism of rock breaking under a pulsed water jet is significant in advancing the application of pulsed water jets in the rock crushing process. Based on continuum mechanics and interpolation theory, this paper establishes a numerical model to simulate the propagation of stress waves in rock by adopting the method of smooth particle hydrodynamics (SPH). According to the simulation results, this paper presents a quantitative approach to schematize the propagation of stress waves in the time-space dimension. The waveforms of stress waves in the selected path and the effective stress history of test particles are obtained to quantitatively describe the propagation of stress waves. Relying on the approach, the effects of jet velocity and rock properties on the propagation of stress waves are investigated. The results show that in the rock model, the influence area, propagation speed and attenuation rate of the stress wave all increase with increasing jet velocity. Moreover, the mean effective stress of a test particle in the numerical model increases with increasing jet velocity. Of the rocks considered in this paper, granite shows the greatest mean effective stress acting on the test particle, propagation speed, and attenuation rate of the stress wave. [ABSTRACT FROM AUTHOR]

To fill the research gap of estimating crack-tip opening displacement (CTOD) under compressive portion within a cyclic loading, a numerical study is conducted in this paper to quantify the influence of compressive stress on CTOD, and a calculation model of CTOD is established for center-cracked plates under tension-compression loading. The residual CTOD and the variable quantity of CTOD are introduced. Based on a series of finite element analyses, a simple relationship between the variable quantity of CTOD and compressive stress is obtained, which considers the influences of plate width, crack length, stress level (the maximum tensile and compressive stresses) and material property (yield stress, elastic modulus and material hardening). Finally, an example is given and the method in this paper is validated. The proposed calculation model of CTOD has a wide application range and is applicable for finite plates of different materials under tension-compression cyclic loading. [ABSTRACT FROM AUTHOR]

The reliability analysis of engineering structural systems with limit state functions defined implicitly by time-consuming numerical models (e.g. finite element analysis structural models) requires the use of efficient solution strategies in order to keep the required computational costs at acceptable levels. In this paper, an adaptive Kriging surrogate model with active refinement is proposed to solve component reliability assessment problems (i.e. involving one single design point) with nonlinear and time-consuming implicit limit state functions with a moderate number of input basic random variables. The proposed model, in the first stage, uses an adaptive Kriging-based trust region method to search for the design point in the standard Gaussian space and predict an initial failure probability based on the first-order reliability method as well as sensitivity factors for the input basic random variables. This initial prediction is then verified or improved efficiently in a second stage using Monte Carlo simulation with importance sampling based on a Kriging surrogate model defined iteratively around the design point using an active refinement algorithm. A convergence criterion that detects the stabilization of the failure probability prediction during the active refinement process is also proposed and implemented. The usefulness of the proposed adaptive Kriging surrogate model in terms of accuracy and efficiency for reliability assessment of engineering structural systems is shown in the paper with two relevant numerical examples, involving a highly nonlinear analytical limit state function in two-dimensions and an advanced nonlinear finite element analysis structural model in a larger dimensional space. [ABSTRACT FROM AUTHOR]

In this paper, supermode characteristics of a dual-core fiber and a four-core fiber are analyzed by a simple couple-mode theory. The effective refractive index and corresponding relative error of each supermode are investigated in detail with different gapsize, relative refractive index and core radius using numerical method and finite element method. Both adjacent coupling and non-adjacent coupling are taken into consideration when keeping single mode condition of each core. The magnitude of relative error can achieve 10 −5 and 10 −4 for a dual-core structure and a four-core structure, respectively. The obtained results clearly show the validation of numerical method compared with finite element method. One is going to benefit from the succinct equation expressions in this paper when designing and analyzing supermode supporting fiber structure. [ABSTRACT FROM AUTHOR]

As the main variable loads during the service stage of Submerged Floating Tunnels (SFTs), traffic loads is an important part in the studies of SFTs’ dynamic response. On the basis of the characteristics of moving vehicles and the structural characteristics of SFTs, this paper puts forward the calculation formula of traffic loads, with a comprehensive consideration of different influencing factors. In this paper, in order to obtain the degrees of influence of such factors on the calculated values of traffic loads and the dynamic response of SFTs and the weight of each factor, the author uses the orthogonal experiment method and the analytic hierarchy process, combining them with a simulation of the finite element software. It is expected to provide reference for related researches on SFTs. [ABSTRACT FROM AUTHOR]

In this paper, we study a weak Galerkin (WG) finite element method for semiconductor device simulations. We consider the one-dimensional drift–diffusion (DD) and high-field (HF) models, which involves not only first derivative convection terms but also second derivative diffusion terms, as well as a coupled Poisson potential equation. The main difficulties in the analysis include the treatment of the nonlinearity and coupling of the models. The weak Galerkin finite element method adopts piecewise polynomials of degree k for the approximations of electron concentration and electric potential in the interior of elements, and piecewise polynomials of degree k + 1 for the discrete weak derivative space. The optimal order error estimates in a discrete H 1 norm and the standard L 2 norm are derived. Numerical experiments are presented to illustrate our theoretical analysis. Moreover, numerical schemes also work out for the discontinuous diffusion coefficient problems. [ABSTRACT FROM AUTHOR]

In metal machining, due to the material around the cutting edge subjected to high pressure, the subsurface generates a plastic deformation layer. And near the edge of finished surface the plastic deformation layer acts as a Poisson burr. This paper proposes an analytical model to predict the sizes of Poisson burr based on Flamant and Boussinseq equations in the plastic deformation problem. Besides the mechanical loading, the thermal effects are also taken into account in this model and assumed as moving heat sources during the cutting. The finite element simulation of aluminum 6061 alloy is utilized to verify the results of theoretical analysis. The results show that the sizes of Poisson burr has a great sensitivity to material properties and processing parameters. In addition, due to the serrated chips and brittle fracture of high strain rate, the Poisson burrs are not continuous along the longitudinal cutting direction. Through comparative study it is found that the theoretical model describes burr sizes with considerable accuracy. As a result, this paper may provide a better understanding the mechanism of Poisson burr formation and the theoretical basis of processing parameters optimization. [ABSTRACT FROM AUTHOR]

This paper is concerned with the finite element simulation of debonding failures in FRP-strengthened concrete beams. A key challenge for such simulations is that common solution techniques such as the Newton–Raphson method and the arc-length method often fail to converge. This paper examines the effectiveness of using a dynamic analysis approach in such FE simulations, in which debonding failure is treated as a dynamic problem and solved using an appropriate time integration method. Numerical results are presented to show that an appropriate dynamic approach effectively overcomes the convergence problem and provides accurate predictions of test results. [ABSTRACT FROM AUTHOR]

In this paper, we develop a novel second order in time, decoupled, energy stable finite element scheme for simulation of Cahn-Hilliard-Hele-Shaw system. The idea of scalar auxiliary variable approach is introduced to handle the nonlinear bulk. An operator-splitting strategy is utilized to fully decouple the coupled Cahn-Hilliard equation and Darcy equation. A full discretization is built in the framework of Galerkin finite element method. The unique solvability of numerical solution and preservation of energy law are rigorously established. Numerical experiences are recorded to illustrate the features of the designed numerical method, verify the theoretical results and conduct realistic applications. [ABSTRACT FROM AUTHOR]

The paper discusses membrane instability phenomena by a Fourier-related double scale approach that was introduced recently. This leads to a reduced-order model that is able to capture the main features of the wrinkles with few degrees of freedom. The paper focuses on the corresponding finite element procedure, its implementation and evaluation and applications to various cases of loading and boundary condition. The finite element model has first been implemented in a home-made code, the nonlinear system being solved by the Asymptotic Numerical Method (ANM), which has advantages of efficiency and reliability for stability analyses. It has also been implemented as a user element in a commercial software to evaluate the effectiveness of the reduction technique. Various loading cases were considered and the numerical tests establish that the reduced model can predict the wrinkling patterns, even when there are few wrinkles. The numerical results highlight the strong influence of a dimensionless parameter for wrinkling initiation. [ABSTRACT FROM AUTHOR]

The paper presents a simplified analytical method to examine the energy absorbing mechanisms of small-scale stiffened plate specimens, quasi-statically punched at the mid-span by a rigid indenter with a knife or a flat edge shape. To validate this method, experiments and numerical simulations are conducted on specimens scaled from a tanker side panel limited by one span between the web frames and the stringers. Therefore, the paper provides practical information to estimate the extent of structural damage within ship side panels during collision accidents. The experimentally obtained force–displacement responses and shapes of the deformation show good agreement with the simulations performed by the explicit LS-DYNA finite element solver. The numerical results manage to describe the process of initiation and propagation of the material fracture in the side panel specimens and provide detailed information of the energy dissipated by each structural component and its contribution to total energy during the entire deformation process. The analytical method derives expressions to estimate the relation between the plastic deformation and the energy dissipation of the stiffened plates. Both the plate and the stiffener elements dissipate the energy through rotation of the plastic hinges at the applied load and the support and the membrane tension over the plastically deformed region between the loading and the supports. The proposed simplified expressions give a good agreement with the experimental and numerical results. [ABSTRACT FROM AUTHOR]

This paper presents a hybrid finite-element/boundary-element method for fluid–structure-interaction simulations of inflatable structures. The flow model consists of the steady Stokes equation, which admits a boundary-integral formulation. The structure is represented by a Kirchhoff–Love shell. The boundary-element approximation of the Stokes equation reduces the flow problem to an integral equation on the actual structure configuration, thus obviating the need for volumetric meshing of the strongly deforming fluid domain. The Stokes model moreover exhibits a lubrication effect that acts as an intrinsic mechanism to treat the ubiquitous self-contact that occurs in inflation problems. The aggregated fluid–structure-interaction problem, composed of the boundary-integral equation and the Kirchhoff–Love shell connected by dynamic and kinematic interface conditions, is approximated by means of isogeometric discretizations to accommodate the smoothness requirements on the approximation spaces imposed by the flexural rigidity in the Kirchhoff–Love shell and to provide an accurate and smooth representation of the boundary for the boundary-element method. Auxiliary results presented in this paper are: (1) a parametrization-free Kirchhoff–Love formulation; (2) establishment of a cubic relationship between distance and tractions due to the lubrication effect; and (3) the interpretation of the Lagrange multiplier pertaining to fluid incompressibility as the total excess pressure. [ABSTRACT FROM AUTHOR]

Composites consisting of carbon fiber and epoxy resin matrix are modern material for wide range of application (automotive, aeronautics, sport industry). In this paper several type of composite material based on bisphenol A epoxy resin and plain/twill carbon cloth was prepared. Subsequently composite consisting from carbon cloth/epoxy resin and carbon nanotubes was prepared to prove the improvement of mechanical properties. Second part of paper describes the possibility of simulation of composite part using NX8 and Nastran solver. Results from real tensile test and simulation were then compared. [ABSTRACT FROM AUTHOR]

Pull-through failure of bolted joints in composites is due to the relatively low through-thickness properties of laminated materials. Recently it has been identified that pull-through failure also plays an important role in the ultimate bearing load and total energy absorption of bolted joints, especially under dynamic conditions. It has been previously found that bolted joints loaded in bearing exhibit rate sensitivity whereas bolts loaded in pull-through experience very little sensitivity, for nearly identical joint configurations. The primary focus of this paper was to use explicit finite element simulation of pull-through failure to shed light on discrepancies between experimentally observed rate sensitivity for seemingly similar tests. The paper uses the stacked-shell modelling approach to efficiently model the interaction of delamination and ply failure under the complex dynamic load state. The results of the simulation indicated that the properties of the interface susceptible to loading rate sensitivity, Mode I and II strain energy release rates (SERRs), did not have a great effect on the overall joint response; despite the prevalence of delamination during the failure process. A weak relationship between Mode II SERR and joint response was discovered which was consistent with experimental observations. [ABSTRACT FROM AUTHOR]

The spiral shafts are usually fabricated by the cutting, this paper uses the cross wedge rolling process of the spiral shaft parts. Firstly, according to the deformation stages of rolling narrow spiral step, accurate shaping surface of the mold is designed. Meanwhile, this paper finds that the starting point of the shaping curve is not in the stretching stage but advances to the knifing stage. Secondly, based on the FE software DEFORM-3D, the rigid-plastic finite element model of the cross wedge rolling of spiral shaft parts was established, and the rolling process was simulated. The forming qualities in both cases of having shaping curve and no shaping curve were compared, from which we can find that the forming quality of having shaping curve is better, it also shows that the shaping curve is correct, and the process of cross wedge rolling of spiral shaft is feasible. [ABSTRACT FROM AUTHOR]

Leveling is a process used to minimize the bending defects in the steel industry. It plays an important role in delivering the desired material properties and product standards. This paper presents an analytical model for predicting the leveling process for H-beams with strong and weak axis bending defects. In this paper, an analytical model is first developed with the computational procedure of describing the continuous bending and reversed bending process, as well as the unloading process. Then, the developed analytical model and computational procedure are evaluated by a comparative study of results obtained from experimental data. Finally, the leveling process including curvature, trajectory, bending and residual stress distributions are evaluated for typical H-beam made of construction steel using the developed method. It is found that defective H-beam with different initial curvature tends to be flatted after the leveling process and the developed analytical model is much superior than finite element based modeling approach in terms of computational efficiency with the same level of accuracy. [ABSTRACT FROM AUTHOR]

This paper describes the numerical simulation of failure mechanisms of coated forming tools and explains the procedure of a finite element analysis (FEA) of the coating - substrate - system. The development of a static failure model is explained using the examples of thermally sprayed and amorphous carbon coatings. Furthermore, its implementation into the FE model is demonstrated. Sprayed thick coatings are used initially, the developed methods are then transferred to amorphous thin coatings. Necessary thermomechanical material properties, especially in the case of thin coatings, as well as system characteristics such as adhesion strength are insufficiently known. Together with FEA several techniques are employed to determine applicable model parameters using parameter identification. The paper only considers monolayers. In a first approximation both substrate and coating are considered homogeneous and isotropic. [ABSTRACT FROM AUTHOR]

This paper presents a model for the simulation of cracks in thin-walled structures using Trefftz-elements (T-elements) for crack tip regions. These elements are based on exact solutions to the governing differential equations and inner boundary conditions, resulting in high resolutions of the stress/strain fields. The T-elements are combined with standard elements using an extended variational principle. Beside this formalism the paper presents the derivation of particular solutions for a straight 2d-crack including a Dugdale strip-yield zone. The results are validated against high-resolution standard finite element simulations. Finally a crack propagation algorithm and some future enhancements are discussed. [ABSTRACT FROM AUTHOR]

This paper presents an investigation on the cause of severe vibration problem of a coach with four-cylinder engine running at an idle state using vibration and impact hammer modal experiments to obtain the main vibration frequency components and the natural characteristics of the coach. The vibration results indicate that the main vibration component comes from the vibration transmitted from the engine to the chassis frame, which is closely related with the engine idle speed. Based on structural simulation analysis of the coach's chassis frame and comparison with modal testing, the coach severe vibration problem was due to coupling resonance between the engine idle frequency and the fourth natural frequency of the chassis frame. The solution to eliminate the vibration problem is provided by changing the local structure stiffness of the chassis frame. The contribution of this paper lies in providing a solution to solve similar problems. [ABSTRACT FROM AUTHOR]

In this paper, the chemotaxis partial differential equations models which describe the movement by one community in reaction to one chemical or biological signal are given and solved numerically on surfaces. The models and the numerical method concerned are in terms of a generic form of chemotaxis models. We develop a new semi-implicit finite element scheme based on the gradient and Laplacian recoveries to linearize the equations. Meanwhile, we modify the proposed semi-implicit scheme as a characteristic form and present a novel strategy for the discretization of characteristic derivative on surface. The lumped mass modification is employed for positivity preservation. And the related analysis results are provided. We investigate the accuracy and convergence of the proposed method by numerical tests. And the simulations of blowing-up solution, pattern formulations and aggregations of bacteria demonstrate the applicability of the proposed methods. [ABSTRACT FROM AUTHOR]

Highlights • A new application of matrix completion for cost reduction in finite element simulations is proposed. • The proposed technique is capable of quantifying both the epistemic and aleatory uncertainties. • A large number of 29,000 time history finite element simulations were performed. • For any practical purposes, this technique reduces the computational cost by almost 80% • The use of side information from a feature matrix is shown to be very effective. Abstract In recent years, uncertainty appears in different aspects of physical simulations including probabilistic boundary, stochastic loading, and multiscale modeling. Stretching across engineering domains and applied mathematics, uncertainty quantification is a multi-disciplinary field which is an inseparable part of risk analysis. However, many real-world problems deal with large number of simulations or experiments. Considering the limited budget and time to perform all these efforts (specially for practitioners), an essential task is to reduce the computational cost in an uncertain environment. This paper proposes to use a matrix completion technique for reducing the overall computational cost of engineering systems when they are subjected to the simultaneous effects of aleatory and epistemic uncertainties with high dimensions. The proposed method is further improved using hidden information in the uncertain variables based on clustering techniques. Several parametric and Monte Carlo simulations were performed to demonstrate the accuracy of our method with different compression ratios. Experimental results show a decent overall performance of our technique for high-dimensional hybrid uncertain systems. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a novel methodology for fast simulation and analysis of transient heat transfer problems. The proposed methodology is suitable for real-time applications owing to (i) establishing the solution method from the viewpoint of computationally efficient explicit dynamics, (ii) proposing an element-level thermal load computation to eliminate the need for assembling global thermal stiffness matrix, leading to (iii) an explicit formulation of nodal temperature computation to eliminate the need for iterations anywhere in the algorithm, (iv) pre-computing the constant matrices and simulation parameters to facilitate online calculation, and (v) utilising computationally efficient finite elements to efficiently obtain thermal responses in the spatial domain, all of which lead to a significant reduction in computation time for fast run-time simulation. The proposed fast explicit dynamics finite element algorithm (FED-FEM) employs nonlinear thermal material properties, such as temperature-dependent thermal conductivity and specific heat capacity, and nonlinear thermal boundary conditions, such as heat convection and radiation, to account for the nonlinear characteristics of transient heat transfer problems. Simulations and comparison analyses demonstrate that not only can the proposed methodology handle isotropic, orthotropic, anisotropic and temperature-dependent thermal properties but also satisfy the standard patch tests and achieve good agreement with those of the commercial finite element analysis packages for numerical accuracy, for three-dimensional (3-D) heat conduction, convection, radiation, and thermal gradient concentration problems. Furthermore, the proposed FED-FEM algorithm is computationally efficient and only consumes a small computation time, capable of achieving real-time computational performance, leading to a novel methodology suitable for real-time simulation and analysis of transient heat transfer problems. [ABSTRACT FROM AUTHOR]

Highlights • A wide gap Hybrid thrust magnetic bearing (HTMB) with passive and active restoring axial forces is presented. • The proposed HTMB features a biconical iron rotor and a U shaped stator core containing the coil and PMs. • The proposed HTMB has linear axial force-current characteristics. • The undesired radial force is almost uncoupled from the windings current in the proposed HTMB. Abstract Active thrust magnetic bearings provide an axial force to balance the moving parts of machines. However, most devices produce null or unbalancing passive forces. Furthermore, reported designs usually feature very small axial and radial gaps. This paper presents a thrust actuator for wide axial gaps that produces both passive and active restoring axial forces. It features a long biconical rotor and a stator housing a single winding and two permanent magnets. Simulations are done using finite-element-analysis (FEA) and compared to magnetic circuit analysis and experimental results from a prototype with a diameter of 48 mm and 20 mm axial displacement. [ABSTRACT FROM AUTHOR]

Abstract This paper proposes to confront a mixed domain decomposition method with industrial computations, in particular the simulation of quasi-static assemblies with frictional contact between the parts. The method is implemented in a non-invasive manner around an industrial finite element software. The performance of the algorithm is studied on industrial assemblies. Highlights • Automatic choice of the mixed parameters based on bounding boxes to approximate the size of subdomains. • A description of the non invasive parallel implementation of the method with the software salome and code-aster. • Applications to complex structures given by our industrial partners. It involves pre-loaded bolts with frictional contact. [ABSTRACT FROM AUTHOR]

Highlights • Detailed description for determination of residual stresses in TWB. • Influence and weight functions for sheets with various thickness transition ratios. • Residual stress profile for FSW butt joints made of AlMgSc 5028 H116. Abstract Residual stresses play a major role in the characterization of welded structures. The Cut-Compliance-method uses fracture mechanics principles and delivers stress intensity factors caused by the residual stresses, which is convenient for the evaluation of components that contain a crack. As sheets with different gauge were friction stir welded (FSW) a geometry with thickness transition evolved. Hence, the required influence function for the Cut-Compliance-method was derived for specimens with thickness transition by means of finite element simulations with fracture mechanical analysis. In order to compute residual stress profiles for the geometry with thickness transition, a weight function solution has been determined as well. Consequently, experimental data in terms of residual stress profiles and corresponding stress intensity factor distribution are obtained and presented in the paper for a FSW butt joint of an AlMgSc alloy (AA5028-H116) with identical and different sheet thicknesses. [ABSTRACT FROM AUTHOR]

Highlights • A continuum damage mechanics (CDM) and XFEM based methodology is developed for high cycle fatigue crack growth simulations. • A new damage model is proposed for the evaluation of fatigue crack growth life. • A new criterion is proposed based on the damage evolution to identify the appropriate definition of stress triaxiality. • A non-local CDM approach is implemented to reduce the mesh sensitivity. • The present methodology is found quite successful for fatigue crack growth simulations. Abstract In this paper, we have developed a continuum damage mechanics (CDM) based methodology for high cycle fatigue crack growth simulations. A fatigue damage law is proposed and implemented in the framework of extended finite element method (XFEM). A new criterion is proposed based on damage evolution to identify the appropriate definition of stress triaxiality for acquiring the constraint effect on the stress state correctly. Few mesh regularization schemes are also employed for reducing the mesh sensitivity in the results. Simulations are performed on fracture specimens of different materials subjected to constant amplitude fatigue loading. The fatigue life of a turbine disc is also predicted under constant amplitude loading. The results obtained from present methodology (CDM and XFEM) are found in good agreement with the published experimental results. These simulations highlight that the continuum damage mechanics is a simple and effective tool to perform crack growth simulations under high cycle fatigue conditions. [ABSTRACT FROM AUTHOR]

Abstract This paper introduces a new approach of breakdown theory using a computer simulation program. Based on the concept of Minimum Stressed Volume Zone (MSVZ) a simulation model of the streamer inception in air using the needle-to-plane configuration is presented. The streamer methodology first requires accurate field computation. The non-uniform electric field distribution is conducted using Poisson's equation, which is solved based on the concept of the Finite Element Method (FEM). The advantage of using FEM in the simulation of streamer progression is the ability to simulate the potential solution for a non-uniform field gap with the external injection of charges at the beginning of each streamer step. The simulation confirms that the streamer radius is 30 μ m , with 10 8 electrons at the streamer tip, then within MSVZ the radius of the streamer filament enlarges to a value of 120 μ m , so, the radius of the streamer leader near stressed high voltage electrode becomes constant at 120 μ m. After that, when the simulated field (E) at the main leader head is supply energy with eight times of critical electric field ( E cr ) value, i.e. the electric field at its tip reaches a value of E / E cr = 8 the streamer starts to branch; thus, a value of E cr of 4.5 kV / cm required for streamer initiation. The new simulation model is assessed via a comparison with other experimental and computational works. Highlights • A new simulation model of the streamer inception in gases is presented. • The non-uniform electric field distribution is conducted using Poisson's equation. • The length of the streamer step and the radius of the streamer filament are approximately equal to 30 μ m. • The critical electric field of 4.5 k V / c m is required for streamer initiation. • The FEM concept is applied using the COMSOL Multiphysics simple software computer program. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • 3D simulation model for calculating GPR and electric field surrounding an earthing system is presented. • The new model presented in two cases (isotropic and anisotropic resistivity). • The proposed model used for single and three driven rods. • Comsol multiphysics is used for the simulation model using FEM principles. Abstract A three-dimensional model for calculating the ground potential rise and the electric field distributed at the ground surface of an earthing system using driven vertical rods is presented. The electric field distribution is obtained by using Laplace's equation which is solved by finite element method. The presented model for simulating electrical field is a three-dimensional field problem with different types of earth models; one and two- layers earth models, in two different cases. The first case is represented by one driven rod while the second one is represented by three driven rods. The strength of the finite element method in this application is in its ability to allow a detailed representation of the types of the soil and different cases of the rod simulation. The new simulation model has been assessed through comparing the vertical field strength over the vertical driven rod surface, with that estimated one in other experimental and computational work. A primarily simulation for investigating the thermal effect is achieved and more investigation about this point will be presented in the future papers. [ABSTRACT FROM AUTHOR]

Highlights • Descriptions of the experimental tests of two large-size RC containment specimens. • Descriptions of CSMM-based shell element for simulation of RC shell-type structures. • Nonlinear FE analysis of the RC containments using CSMM-based shell element. • Discussions and comparisons of experimental outcomes and analytical results. Abstract The nuclear containment structure is one of the most important infrastructure systems ensuring the safety of a nuclear power plant. The structural behavior of a cylindrical containment structure made of reinforced concrete (RC) with large dimensions and numerous rebars is complex and difficult to predict. The complex behavior of the RC containment structure has been investigated in an international collaboration project between the National Center for Research on Earthquake Engineering (NCREE) in Taipei, Taiwan and the University of Houston (UH), Houston, Texas. At NCREE two 1/13 scaled cylindrical RC containment specimens were tested under reversed cyclic loads [1]. At UH, a finite element simulation of the two tested specimens was developed using a finite element analysis (FEA) program SCS [2]. In the program, a new shell element, the so-called CSMM-based shell element, was developed based on the Cyclic Softened Membrane Model [3] and the formulation of an 8-node Serendipity curved shell element [4] with a multi-layer approach [5]. The UH simulated seismic behavior was close to the NCREE experimental results. This paper presents the theoretical development of the FEA program SCS and the comparisons of its predictions with the experimental structural behavior of the two RC containment specimens. This simulation model and the FEA program are excellent tools to develop effective performance-based design provisions. [ABSTRACT FROM AUTHOR]

Highlights • Structural test and analysis data in one consistent data model. • Using ISO 10303 STEP AP209 to keep the traceability between structural testing and analysis. • Improving data retention of structural test and simulation data using STEP. Abstract This paper proposes a method for incorporating FEA data and structural test data into one common standardized data model based on the ISO 10303 STEP Standard [1]. The proposed method takes advantage of data structures and elements defined in STEP AP209 Edition 2 [2] to provide traceability between analysis and testing phases; information such as sensor and finite elements, test and FEA load cases, and test and FEA results are included. It also presents an introduction to STEP and AP209e2, and discusses how it can be used in a Simulation Data Management environment. [ABSTRACT FROM AUTHOR]

Abstract Parameter-adaptive variational mode decomposition (VMD) has attenuated the dominant effect of prior parameters, especially the predefined mode number and balancing parameter, which heavily trouble the traditional VMD. However, parameter-adaptive VMD still encounters some problems when it is applied to the data from industry applications. On one hand, the mode number chosen using parameter-adaptive VMD is not the optimal. Numbers of redundant modes are decomposed. On another hand, parameter-adaptive VMD has much space for the improvement when it is applied to compound-fault diagnosis. To solve these issues and further enhance its performance, an improved parameter-adaptive VMD (IPAVMD) is proposed in this paper. Firstly, a new index, called ensemble kurtosis, is constructed by combining with kurtosis and the envelope spectrum kurtosis. It can simultaneously take the cyclostationary and impulsiveness into consideration. Secondly, the optimization objective function of grasshopper optimization algorithm is improved based on the ensemble kurtosis. The improved method chooses the mean value of the ensemble kurtosis of all modes rather than that of the individual mode as objective function. Thirdly, to extract all potential fault information, an iteration algorithm is used in the new method. Benefiting from these improvements, the proposed IPAVMD outperforms the traditional parameter-adaptive VMD and further expands the application to compound-fault diagnosis. It has been verified by a series of simulated signals and a real dataset from the axle box bearings of locomotive. Highlights • Benefiting from the proposal of ensemble kurtosis and new optimization objective function, IPAVMD can provide a better solution for the selection of VMD prior parameters. • IPAVMD can obtain the satisfying decomposition results with higher efficiency than the original parameter-adaptive VMD method. [ABSTRACT FROM AUTHOR]

Highlights • A more appropriate FE model was proposed to predict the CCI and CCG behavior. • The effects of simulation method on CCI and CCG of brazed joint are investigated. • The brazed RS can promote CCI and enhance CCG rate, thus reducing creep life. • The predicted results by single-material method agree well with the experiment. • Bigger uniaxial creep strain can prolong the CCI time and reduce the CCG rate. Abstract In this paper, a more appropriate finite element (FE) model was proposed to predict the creep crack initiation (CCI) and growth (CCG) behavior of HastelloyC276-BNi2 brazed joint at high temperature. The effects of single-material, bi-material and three-material method on CCI and CCG behavior have been discussed fully. The relationships between CCG rate and parameter C ∗ for different simulation methods were obtained. The results show that the simulation method has a great influence on CCI and CCG behavior of brazed joint. The brazed residual stress (RS) can accelerate CCI and enhance CCG rate, leading to the reduction of creep life. The CCI time and creep life predicted by single-material method is smaller than those by bi-material and three-material method. The creep life and crack growth morphology predicted by single-material method have a good consistent with the experimental results. The single-material method can accurately predict the CCG behavior of brazed joints. Bigger uniaxial creep strain can prolong the CCI time and reduce the CCG rate. The creep life of brazed joint can be enhanced by increasing uniaxial creep strain. [ABSTRACT FROM AUTHOR]

Abstract Finite element models of biomedical applications increasingly use anisotropic hyperelastic material formulations. Appropriate material parameters are essential for a reliable outcome of these simulations, which is why planar biaxial testing of soft biological tissues is gaining importance. However, much is still to be learned regarding the ideal methodology for performing this type of test and the subsequent parameter fitting procedure. This paper focuses on the effect of an unknown sample orientation or a mistake in the sample orientation in a planar biaxial test using rakes. To this end, finite element simulations were conducted with various degrees of misalignment. Variations to the test method and subsequent fitting procedures are compared and evaluated. For a perfectly aligned sample and for a slightly misaligned sample, the parameters of the Gasser-Ogden-Holzapfel model can be found to a reasonable accuracy using a planar biaxial test with rakes and a parameter fitting procedure that takes into account the boundary conditions. However, after a certain threshold of misalignment, reliable parameters can no longer be found. The level of this threshold seems to be material dependent. For a sample with unknown sample orientation, material parameters could theoretically be obtained by increasing the degrees of freedom along which test data is obtained, e.g. by adding the data of a rail shear test. However, in the situation and the material model studied here, the inhomogeneous boundary conditions of the test set-ups render it impossible to obtain the correct parameters, even when using the parameter fitting method that takes into account boundary conditions. To conclude, it is always important to carefully track the sample orientation during harvesting and preparation and to minimize the misalignment during mounting. For transversely isotropic samples with an unknown orientation, we advise against parameter fitting based on a planar biaxial test, even when combined with a rail shear test. [ABSTRACT FROM AUTHOR]

This paper proposes a three-dimensional model incorporating finite element (FE) meshes with infinite element (IE) boundaries for ballasted railways. Moving train loads are simulated with sliding motions of moving elements which have hard contact feature at the interface with supporting rails. Dynamic responses of ballasted railway under different train speeds are investigated in time domain and frequency domain to identify the predominant frequency and critical speed. Rayleigh wave (R-Wave) propagation is simulated using the combined FE-IE model to determine the velocity of R-Wave in the layered embankment model and its relationship with the critical speed of the ballasted railway. The proposed model is successfully validated against the results of Euler-Bernoulli Elastic Beam (E-BEB) model. [ABSTRACT FROM AUTHOR]

Recently, the market promotion of wireless power transfer (WPT) products has generated great expectations for systematic design and optimization of practical WPT system (especially the coupler). The existing optimization methods usually employ the Finite Element Analysis (FEA) to simulate the magnetic field, where the effects and requirements of overall circuit are neglected. To address this issue, an optimization approach for the coupler based on circuit simulation is proposed in this paper, and the secondary compensation capacitor is further optimized to improve the system performance. The simulation model is embedded into Simulink and the calculation part is embedded into MATLAB, where the objective is to achieve the maximum efficiency by searching three variables under adequate constraints. The numerical results imply that the proposed method is more effective and accurate than the traditional trial-and-error way, and that it suits the practical WPT system design excellently. [ABSTRACT FROM AUTHOR]

Abstract In a hyper-connected society, IoT environment, markets are rapidly changing as smartphones penetrate global market. As smartphones are applied to various digital media, development of a novel smart product is required. In this paper, a Smart Product Design-Finite Element Analysis Process (SPD-FEAP) is developed to adopt fast-changing tends and user requirements that can be visually verified. The user requirements are derived and quantitatively evaluated from Smart Quality Function Deployment (SQFD) using WebData. Then the usage scenarios are created according to the priority of the functions derived from SQFD. 3D shape analysis by Finite Element Analysis (FEA) was conducted and printed out through Rapid Prototyping (RP) technology to identify any possible errors. Thus, a User Customized Smart Keyboard has been developed using SPD-FEAP. Graphical abstract Image 1 Highlights • Quantitative and qualitative analysis of user requirements. • 3D shape analysis by FEA. • User customized smart keyboard verification via RP. [ABSTRACT FROM AUTHOR]

Misalignment is a prevalent problem in rotor machinery. This paper proposes a numerical analysis for the mixed EHL of finite-line contacts considering tilting loads based on FEM. The Reynolds and linear elasticity equations, and Greenwood-Tripp contact model are coupled in an iterative process to solve the fluid-solid/solid-solid interaction under the compound external force and moment. Lubrication characteristics at both ends of the cylinder are analyzed and an asymmetric profile design scheme is presented to improve the lubrication performance at the cylinder's lower end. It is found that proper profile parameters can reduce EHL pressure by 40%, increasing the minimum oil film thickness by up to 100%, and thus reduce asperity contact pressure by up to 50%. • An FE model for the mixed EHL analysis of finite line contacts is developed. • The compound loading condition including the external force and moment is considered. • Lubrication characteristics of tilted finite line contact are analyzed and disclosed. • The asymmetric profile design scheme is proposed to improve lubrication performance. [ABSTRACT FROM AUTHOR]

In this paper, the effects of geometric skewness and abutment restraint on the fire resistance of a real highway bridge have been studied. Four finite element models have been investigated using rectangular and skew shapes with and without modelling the abutment. The investigation has been carried out in three steps: 1) heat transfer analysis under a specified hydrocarbon fire; 2) simulation of the thermo-mechanical response of the bridge superstructure over the entire duration of the fire using beam and shell elements to represent the structural components; 3) detailed processing and interpretation of the simulation results to understand and illustrate the global response of the structure by comparing all the models. Results indicate that a skew bridge may possess greater inherent resistance to fire. For the two-span highway bridge model, restraint from the abutment does not affect the estimated failure time significantly. [ABSTRACT FROM AUTHOR]

Industrials have an intensive use of numerical simulations in order to avoid physical testing and to speed up the design stages of their products. The numerical testing is indeed quicker to set-up, less expensive, and supplies a lot of information about the system under study. Moreover, it can be much closer to the physical tests as the computation power increases. Despite the rise of this power, time consuming simulations remain challenging to be used in design process, especially in an optimization study. Crash simulations belong to this category. These rapid dynamic computations are used by RENAULT during the sizing of the vehicle structure in order to ensure that it meets specifications set up to reach safety criteria in case of accidents. They are completed using finite element software such as VPS (Virtual Performance Solver) developed by ESI group that will be used in this study. For car manufacturers, the goal of the optimization study is to minimize the mass of the vehicle (and thus its consumption) by modifying the thicknesses of some parts (from 20 to 100 variables). Industrials such as RENAULT currently perform optimization studies based on numerical design of experiments. The number of computations required by this technique is from 3 to 10 times the number of variables. This is too much in order to be intensively used in a design process. In order to decrease the time-to-market and to explore alternative technical solutions, we explore the potential of using a parametrized reduced order model in the optimization studies. The parametrized reduced order model gives an estimation of the high-fidelity result for a new set of parameters without using the solver, by analysing the existing results of previous computations with various sets of parameters. The developed reduced order model is called ReCUR. It is partly based on a CUR approach embedded in a regression analysis. The regression statistical model uses the data of a few calculations made with the solver. Other tools such as clustering and linear programming are used to get the regression analysis more efficient. It is hoped to drastically reduce the number of required simulations of a standard optimization study. In this paper, the construction of the reduced order model will be presented. Then, the relevancy of using the reduced order model into a design process will be exhibited through the treatment of two industrial test-cases. Some improvements of the method as well as several potential uses will then be outlined. The applications will highlight the promising power of the method to shorten design process using optimization and long-run simulations. [ABSTRACT FROM AUTHOR]