For Finite Element Method Research Articles

Fluid-Structure Interaction in Microchannel Using Lattice Boltzmann Method and Size-Dependent Beam Element

AbstractFluid-structure interaction (FSI) problems in microchannels play prominent roles in many engineering applications. The present study is an effort towards the simulation of flow in microchannel considering FSI. Top boundary of the microchannel is assumed to be rigid and the bottom boundary, which is modeled as a Bernoulli-Euler beam, is simulated by size-dependent beam elements for finite element method (FEM) based on a modified couple stress theory. The lattice Boltzmann method (LBM) using D2Q13 LB model is coupled to the FEM in order to solve fluid part of FSI problem. In the present study, the governing equations are non-dimensionalized and the set of dimensionless groups is exhibited to show their effects on micro-beam displacement. The numerical results show that the displacements of the micro-beam predicted by the size-dependent beam element are smaller than those by the classical beam element.

J0410301 インデンテーション試験による主応力面を考慮した定常クリープ特性評価法([J041-03]工業材料の変形特性・強度およびそのモデル化 クリープ・変態・被膜強度・締結,機械材料・材料加工部門)

Estimation methods for the creep properties by measuring the micro size deformation is required for finite element method (FEM) analysis considering the creep deformation of the solder joint in-situ. The indentation creep test is one of the effective methods to directly evaluate the creep deformation of solder joint. However, the indentation test cannot give the same creep properties as the creep properties obtained by the uniaxial creep tests using a bulk specimen. The authors proposed an indentation test conducted under a constant depth to determine a suitable reference area, which leads to the same creep characteristics as those obtained by the uniaxial creep test. One of the remaining problems of the indentation test is the reference area cannot be determined without the creep data obtained by the uniaxial creep test. In this paper, a method to determine the reference area without the uniaxial creep tests using a bulk specimen is proposed. For the determination of the new reference area, numerical indentation tests under a constant depth process for four kinds of solder alloys were conducted by FEM. The numerical simulation showed that the reference area obtained considering the distribution of the principal stress gives the almost same creep characteristic as that obtained by the uniaxial creep using bulk specimens.

An efficient GPU acceleration format for finite element analysis

This paper proposes a new Graphics Processing Unit (GPU)-accelerated storage format to speed up Sparse Matrix Vector Products (SMVPs) for Finite Element Method (FEM) analysis of electromagnetic problems. A new format called Modified Compile Time Optimization (MCTO) format is used to reduce much execution time and design for hastening the iterative solution of FEM equations especially when rows have uneven lengths. The MCTO-applied FEM is about 10 times faster than conventional FEM on a CPU, and faster than other row-major ordering formats on a GPU. Numerical results show that the proposed GPU-accelerated storage format turns out to be an excellent accelerator.

Efficient modeling of coil filament losses in 2D

Purpose – The authors aim to search for a practical and accurate way to get good loss estimates for coil filaments in electrical machines, for example transformers. At the moment including loss estimations into standard finite element computations is prohibitively expensive for large coils. Design/methodology/approach – A low-dimensional function space for finite element method (FEM) is introduced on the filament-air interface and then extended into the filament to significantly reduce the number of unknowns per filament. Careful choice of these extensions enables good loss estimate accuracy. The result is a system matrix assembly block that can be used verbatim for all filaments, further reducing the cost. Both net current and voltage per length of the filament are readily available in the problem formulation. Findings – The loss estimates from the developed model agree well with traditional FEM and the computation times are faster. Originality/value – To produce accurate loss estimates in large coils, t...

Determination of pitting sensitivity of the aluminium alloy EN AW-6060-T6 in a carbon-fibre reinforced plastic/aluminium rivet joint by finite element simulation of the galvanic corrosion process

The galvanic corrosion of a rivet joint combining an EN AW-6060-T6 aluminium sheet and a CFRP (carbon fibre reinforced plastic) laminate by an Almac®-coated self-piercing rivet was investigated electrochemically in a 5wt% NaCl solution. The corrosion parameters of the joint components were separately determined by potentiodynamic polarisation and were used for finite-element-method (FEM) simulations to analyse the galvanic corrosion behaviour at joint conditions. A critical distance for galvanic induced pitting corrosion at the aluminium alloy surface was determined by FEM and confirmed by an immersion test in the same environment.

3207 鉄道車両の床下機器の高減衰弾性支持による車体弾性振動低減 : 新幹線相当車両における数値的検討と実車加振試験(OS1-2 振動の低減,OS1 交通・物流システムの高速化、利便性、快適性の向上,オーガナイズド・セッション(OS))

In this paper, we investigated the effect of reduction of flexural vibration in a railway vehicle carbody by supporting underfloor equipment using high-damping elastic mounts. At first, a numerical model for finite element method (FEM) simulation was built to check the reduction capability of flexural vibration by this method. Then, we developed underfloor equipment units with elastic mounts and dummy weight, so as to be able to easily change the layout and the mass of underfloor equipment. And excitation tests of a Shinkansen-type test vehicle with the underfloor equipment units were conducted, and good vibration reduction performance was observed in the tests.

Natural element method for radiative heat transfer in two-dimensional semitransparent medium

The natural element method (NEM) is employed for solving radiative heat transfer problem in a two-dimensional enclosure containing an absorbing, emitting and isotropically scattering medium. Medium boundaries are considered to be opaque, diffuse as well as gray. The NEM referred to as natural neighbor Galerkin method is a new technique in the field of computational mechanics and can be considered as a meshless numerical method. Unlike most of other meshless methods such as element-free Galerkin method or those based on radial basis functions, the shape functions used in NEM, which are based on the Voronoi tesselation of a set of nodes, are strictly interpolant and the essential boundary conditions can be imposed by directly substituting the corresponding terms in the system of equations. Three types of radiative heat transfer problems are addressed. For pure radiation, studies are made for three representative benchmark problems dealing with radiative equilibrium and non-radiative equilibrium. For coupled heat transfer, transient conduction and radiation problem in a rectangular geometry, steady conduction and radiation problem in a gray cylindrical ring are solved. For these problems considered, tests are presented for various parameters, such as the aspect ratio, conduction-radiation parameter, optical thickness, scattering albedo and surface emissivity. Results for NEM are compared with those for finite element method (FEM) generated by the authors and those reported in the literatures. By comparison, it is shown that NEM is efficient, accurate and stable, and can be used for solving radiative heat transfer problem in 2-D semitransparent media.

ANALYTICAL MODELING OF THE EFFECT OF THE TOOL FLANK WEAR WIDTH ON THE RESIDUAL STRESS DISTRIBUTION

Tool flank wear has significant effects on the cutting process, as it affects cutting forces, temperature and residual stresses. In this article, analytical models are developed to predict the cutting temperature and residual stresses in the orthogonal machining of a worn tool. In these models, measured forces, cutting conditions, tool geometry, and material properties are used as inputs. Stresses resulting from thermal stresses, fresh tool stresses and stresses due to tool flank wear are used in this analytical elasto-plastic model, and the residual stresses are determined by a relaxation procedure. The analytical model is verified experimentally with X-ray diffraction measurements. With the analytical model presented here, accurate residual stress profiles in worn tools are shown, while the computational time is significantly reduced from days, typical for finite-element method (FEM) models, to seconds.

Loaded Meshing Simulation of Face-gear Drive with Spur Involute Pinion Based on Finite Element Analysis

The transmission performance,contact stress and bending stress of face-gear drive under torque are studied.Based on the calculated results of Hertz contact theory,a method to get reasonable amounts of grid for finite element method(FEM),is introduced.According to the contact ratio,it investigates the applications of FEM with five teeth,and one with seven teeth,which are used to research on the loaded meshing simulation of face-gear drive.The dangerous positions for contact stress and bending stress of face-gear are found,and their values are given out.The transmission performance of face-gear drive,such as contact ratio,transmission error and the loading distribution coefficient,can be computed by this method.When the face gear is under different torques,their relationship to loadings can be got.The results of research turn out that,the grid size of finite element model,which is decided by Hertz contact theory,is reasonable.The values of stresses in the meshing simulation are reliable,and the conclusions about the transmission performance of face-gear drive are correct.

Reconstruction and Mesh Simplification of Tooth Model

A method for reconstruction of tooth model based on rotate scanning using structured light match technology was proposed. And an algorithm of mesh simplification of the surface point of tooth model using section lines sampling with fixed angles was achieved, which can provide regular surface mesh points for finite element method (FEM). Experiments showed that the method and algorithm could generate accurate surface mesh model which can provide excellent data support for finite element biomechanical model analysis.

Inverse computation of cohesive fracture properties from displacement fields

The cohesive zone model (CZM) is a key technique for finite element (FE) simulation of fracture of quasi-brittle materials; yet its constitutive relationship is usually determined empirically from global measurements. A more convincing way to obtain the cohesive relation is to experimentally determine the relation between crack separation and crack surface traction. Recent developments in experimental mechanics such as photoelasticity and digital image correlation (DIC) enable accurate measurement of whole-field surface displacement. The cohesive stress at the crack surface cannot be measured directly, but may be determined indirectly through the displacement field near the crack surface. An inverse problem thereby is formulated in order to extract the cohesive relation by fully utilizing the measured displacement field. As the focus in this article is to develop a framework to solve the inverse problem effectively, synthetic displacement field data obtained from finite element analysis (FEA) are used. First, by assuming the cohesive relation with a few governing parameters, a direct problem is solved to obtain the complete synthetic displacement field at certain loading levels. The computed displacement field is then assumed known, while the cohesive relation is solved in the inverse problem through the unconstrained, derivative-free Nelder–Mead (N–M) optimization method. Linear and cubic splines with an arbitrary number of control points are used to represent the shape of the CZM. The unconstrained nature of N–M method and the physical validity of the CZM shape are guaranteed by introducing barrier terms. Comprehensive numerical tests are carried out to investigate the sensitivity of the inverse procedure to experimental errors. The results show that even at a high level of experimental error, the computed CZM is still well estimated, which demonstrates the practical usefulness of the proposed method. The technique introduced in this work can be generalized to compute other internal or boundary stresses from the whole displacement field using the FE method.

A downloadable meshed human canine tooth model with PDL and bone for finite element simulations

Objective The aim of this study is to relieve scientists from the complex and time-consuming task of model generation by providing a model of a canine tooth and its periradicular tissues for Finite Element Method (FEM) simulations. Methods This was achieved with diverse commercial software, based on a micro-computed tomography of the specimen. Results The Finite Element (FE) Model consists of enamel, dentin, nerve (innervation), periodontal ligament (PDL), and the surrounding cortical bone with trabecular structure. The area and volume meshes are of a very high quality in order to represent the model in a detailed form. Material properties are to be set individually by every user. The tooth model is provided for Abaqus ®, Ansys ®, HyperMesh ®, Nastran ® and as STL files, in an ASCII format for free download. Significance This can help reduce the cost and effort of generating a tooth model for some research institutions, and may encourage other research groups to provide their high quality models for other researchers. By providing FE models, research results, especially FEM simulations, could be easily verified by others.

E3 Dynamic Characteristics Design System for 3D Nanostructure Fabricated by FIB-CVD(Other manufacturing-related technologies)

Small size structures of diamond-like carbon (DLC) deposited by FIB-CVD contain microscopic non-uniformity in its mechanical properties. This is mainly due to containing Ga implanted by Ga ion irradiation during deposition. In studying applications of DLC nanostructures to mechanical devices, the non-uniform properties cause difficulties in designing nanomechanical devices. In order to establish a modeling method for nanomechanical device design, precise mechanical property evaluation was studied. For the property characterization, several techniques such as transmission electron microscope (TEM), ion implantation simulation and density measurement by vibration were examined. Then, an analysis model for Finite Element Method (FEM)-based dynamic characteristic designing was built up.

OS0109 ガラス質中空球強化複合材料の温度による機械的特性の変化(弾性数理解析とその応用,オーガナイズドセッション)

In this study, the thermal conductivity of Sirasu Balloon/Epoxy composites was examined in order to evaluate mechanical and thermal property of the composites in temperature environmental conditions. The matrix resin of the composite is epoxy resin and its dispersion is micro glassy "Sirasu Balloon". The composite system developed is a kind of micro porous materials. A homogenization theory with multi-scale analytical method is described for evaluation of the thermal conductivity of the composites. From the experimental results, we proposed a unit cell model of micro porous materials for Finite Element Method (FEM) analysis. FEM analysis method was described for evaluation of the composite material system in temperature environmental conditions. By using the unit cell model and setting the mechanical and thermal properties of each material at the temperature, some numerical calculations were performed for the mechanical properties and thermal conductivity of composites. Analytical results made good agreement with experimental results in the temperature conditions.

New adaptive mesh development for accurate near‐field enhancement computation

An accurate computation of the near-field enhancement is a key factor for the optimization of nanostructures in plasmonics. This problem has been addressed for Green's dyadic method but remains open for finite element method (FEM) where the use of non-Cartesian meshes is known to be the most efficient. We present a new adaptive mesh process based on the a posteriori error indicator estimation on the physical solution. This new procedure accelerates drastically the convergence of the solution and minimizes both the memory requirement and the computational time.

Finite element simulation of quench distortion in a low-alloy steel incorporating transformation kinetics

The uncontrolled distortion of steel parts has been a long-standing and serious problem for heat treatment processes, especially quenching. To get a better understanding of distortion, the relationship between transformation kinetics and associated distortion has been investigated using a low-alloy chromium steel. Because martensite is a major phase transformed during the quenching of steel parts and is influential in the distortion, a new martensite start ( M s) temperature and a martensite kinetics equation are proposed. Oil quenching experiments with an asymmetrically cut cylinder were conducted to confirm the effect of phase transformations on distortion. ABAQUS and its user-defined subroutines UMAT and UMATHT were used for finite element method (FEM) analysis. The predictions of the FEM simulation compare well with the measured data. The simulation results allow for a clear understanding of the relationship between the transformation kinetics and distortion.

Finite element method based simulation of stress–strain field in the quenching process

In the paper, some hypotheses for the elastic–plastic metal material in quenching process are given. According to these hypotheses, Mises yield criteria and Prandtl–Reuss flow rule, the stress–strain relationships of elastic and plastic regions in quenched material are attained. Some key technologies for finite element method (FEM) based simulation of quenching process are presented, such as FEM equations of elastic–plastic problem, the method of computing right row vector, convergence regulation, elastic–plastic ratio and initial strains in quenched material. A finite element simulation software for evaluating the stress/strain fields in quenched material is developed. A thermal elastic–plastic problem with phase-transformation and a thermal elastic problem without phase-transformation are simulated using the software. The comparisons between the simulation results and experimental/analytical results show that the simulation results are consistent with the experimental results or the analytical results.

Numerical analysis for bifurcation fracture of sheet metal forming

Abstract A new simulation code for finite element (FE) analysis is proposed for sheet metal forming with bifurcation fracture. Dynamic solution of the FE method is used instead of static solution, because the computational time using dynamic code increases linearly, whereas the time for using static code increases as self-multiplication according to increasing numbers of node. The dynamic code is also applied to a deformation of elasto-viscoplastic material because plastic deformation of real metal can be explained by dislocation theory and expressed by a mechanical model with viscosity. Moreover, this code can simulate bifurcation fracture in a process of plastic working, because the fracture is treated as a separation along a connected surface between two elements instead of disappearance of element stiffness.

Dental versus mandibular biomechanics: the influence of the PDL on the overall structural behaviour

The aim of this study is to relieve scientists from the complex and time-consuming task of model generation by providing a model of a canine tooth and its periradicular tissues for Finite Element Method (FEM) simulations.This was achieved with diverse commercial software, based on a micro-computed tomography of the specimen.The Finite Element (FE) Model consists of enamel, dentin, nerve (innervation), periodontal ligament (PDL), and the surrounding cortical bone with trabecular structure. The area and volume meshes are of a very high quality in order to represent the model in a detailed form. Material properties are to be set individually by every user.The tooth model is provided for Abaqus®, Ansys®, HyperMesh®, Nastran® and as STL files, in an ASCII format for free download.This can help reduce the cost and effort of generating a tooth model for some research institutions, and may encourage other research groups to provide their high quality models for other researchers. By providing FE models, research results, especially FEM simulations, could be easily verified by others.

Knowledge-Based Engineering System for Designing Automotive Fuel Pump Module

We developed a knowledge-based engineering system for designing automotive fuel pump module. This system enables fuel pump module to be designed faster with greater reliability. The system has following four main features : (1) database that enables systematic organization of design knowledge, (2) a design process navigator that guides design procedures, (3) a structural evaluation tool that supports the setting of boundary condition for finite element method (FEM) analysis, and (4) fuel gauge character design and suction performance simulator that are connected to a 3 dimensional computer aided design (3 D-CAD) tool. The effectiveness and reliability of the system was confirmed by designing a test fuel pump module. The total design time was decreased by 1 690 minutes less than manual operation, and the system contributed to improvements in design reliability.