An enriched finite element method for efficient solutions of transient heat diffusion problems with multiple heat sources

Engineering with Computers - We propose an efficient formulation using the framework of Generalized Finite Element Method (GFEM) for the solutions of transient heat diffusion problems having...     

Relations between FEM and FVM applied to the poisson equation

The Finite Volume Method (FVM) with Voronoi bosex for discretizing elliptic boundary value problems is discussed. For this method the matrix of the linear system of equations is shown to be equal to the matrix for the Finite Element Method (FEM) iff a Delaunay triangulation is used.     

A combined DEM–FEM numerical method for Shot Peening parameter optimisation

A numerical modelling approach capable of simulating Shot Peening (SP) processes of industrial interest was developed by combining the Discrete Element Method (DEM) with the Finite Element Method (FEM).In this approach, shot–shot and shot–target interactions as well as the overall shot flow were simulated efficiently using rigid body dynamics. A new algorithm to dynamically adapt the coefficient of restitution (CoR) for repeated impacts of shots on the same spot was implemented in the DEM code to take into account the effect of material hardening. Then, a parametric study was conducted using the Finite Element Method (FEM) to investigate the influence of the SP parameters on the development of residual stresses.Finally, a two-step coupling method is presented to combine the output of DEM simulation with FEM analyses to retrieve the Compressive Residual Stresses (CRS) after multiple impacts with the aim to evaluate the minimum area required to be modelled to realistically capture the field of residual stresses. A series of such coupled analyses were performed to determine the effect of peening angle and the combination of initial velocity and mass flow rate on CRS.     

基于边界面法的完整实体应力分析理论与应用

提出基于边界面法（Boundary Face Method,BFM）的完整实体应力分析方法.在该分析中,避免对结构作几何上的简化,结构的所有局部细节都按实际形状尺寸作为三维实体处理.以边界积分方程为理论基础的BFM是完整实体应力分析的自然选择.在该方法中,边界积分和场变量插值都在实体边界曲面的参数空间里实现.高斯积分点的几何数据,如坐标、雅可比和外法向量都直接由曲面算得,而不是通过单元插值近似获得,从而避免几何误差.该方法的实现直接基于边界表征的CAD模型,可做到与CAD软件的无缝连接.线弹性问题的应用实例表明,该方法可以简单有效地模拟具有细小特征的复杂结构,并且计算结果的应力精度比边界元法（Boundary Element Method,BEM）和有限元法（Finite Element Method,FEM）高.     

Development of an RVE using a DEM–FEM scheme under modified approximate periodic boundary condition to estimate the elastic mechanical properties of open foams

Engineering with Computers - In this article, a methodology based on Discrete Element Method (DEM) and Finite Elements Method (FEM) combined with modified Approximate Periodic Boundary Condition...     

基于ANSYS的铝电解槽电场数值仿真研究

铝电解槽的电场作为形成各物理场的基础,其分布好坏直接影响电解槽的生产。采用基于ANSYS的仿真分析方法研究了铝电解槽的电场分布。采用有限元法,建立了铝电解槽电场的数学模型,并利用有限元仿真分析软件ANSYS建立电解槽三维电场有限元模型,计算了铝电解槽各导电部分的电场分布,总结了分布规律,为电解槽多物理场优化提供基础。其仿真结果与实测结果相吻合,验证了方法的正确性。     

复合材料层合板非线性热振动分析

采用有限元方法研究复合材料层合板结构在线性温度场作用下非线性热振动特性．采用特征值屈曲分析方法,判断了结构在线性温度场作用下的临界屈曲分歧点,计算了结构的一阶弯曲固有频率,分析了铺层角度及铺层层数对结构临界屈曲温度分布和结构固有频率的影响,总结了其对复合材料层合板结构热振动特性影响的一般规律．这些结论对复合材料结构设计、抗热设计有一定的指导意义．     

Cubical Mass-Spring Model design based on a tensile deformation test and nonlinear material model

Mass-Spring Models (MSMs) are used to simulate the mechanical behavior of deformable bodies such as soft tissues in medical applications. Although they are fast to compute, they lack accuracy and their design remains still a great challenge. The major difficulties in building realistic MSMs lie on the spring stiffness estimation and the topology identification. In this work, the mechanical behavior of MSMs under tensile loads is analyzed before studying the spring stiffness estimation. In particular, the performed qualitative and quantitative analysis of the behavior of cubical MSMs shows that they have a nonlinear response similar to hyperelastic material models. According to this behavior, a new method for spring stiffness estimation valid for linear and nonlinear material models is proposed. This method adjusts the stress-strain and compressibility curves to a given reference behavior. The accuracy of the MSMs designed with this method is tested taking as reference some soft-tissue simulations based on nonlinear Finite Element Method (FEM). The obtained results show that MSMs can be designed to realistically model the behavior of hyperelastic materials such as soft tissues and can become an interesting alternative to other approaches such as nonlinear FEM.     

Numerical–experimental crack growth analysis in AA2024-T3 FSWed butt joints

This paper deals with a numerical and experimental investigation on the influence of residual stresses on fatigue crack growth in AA2024-T3 friction stir welded butt joints. The computational approach is based on the sequential usage of the Finite Element Method (FEM) and the Dual Boundary Element Method (DBEM). Linear elastic FE simulations are performed to evaluate the process induced residual stresses, by means of the contour method. The computed stress field is transferred to a DBEM environment and superimposed to the stress field produced by a remote fatigue traction load applied on a friction stir welded cracked specimen; the crack propagation is then simulated according to a two-parameter growth model. Numerical results have been compared with experimental data showing good agreement and evidencing the predictive capability of the proposed method. The obtained results highlight the influence of the residual stress distribution on crack growth.     

Finite element method analysis of Fokker–Plank equation in stationary and evolutionary versions

The problems that often arise in stochastic dynamics can be investigated using the Fokker–Planck (FP) equation. The response of a such systems being subjected to additive and/or multiplicative random noise is represented by probability density function (PDF) that gives the full information about a response random character. Various analytic and semi-analytic solution methods have been developed for various systems to obtain results requested. However numerical approaches offer a powerful alternative. In particular the Finite Element Method (FEM) seems to be very effective. A couple of single dynamic linear/non-linear (Duffing and Van Der Pol type) systems under additive and multiplicative random excitations are discussed using FEM as a solution tool of the FP equation. The resulting PDFs are analyzed and if the analytic results exist mutually compared.     

基于有限元方法的半导体器件电一热分析

随着微电子技术的迅猛发展,各种微电子设备获得了空前广泛的应用,电子系统对电磁干扰的敏感程度也随之增加。在电磁脉冲的影响下,电子系统中的晶体管会发生电、热击穿,因此,半导体器件的可靠性日益成为电磁兼容性领域的关键问题。为了研究半导体器件在常见电磁脉冲影响下的可靠性问题,本文采用了一种混合时域有限元方法,对半导体器件进行综合的电-热分析,通过计算机仿真数值求解半导体物理方程和热力学方程,获得在电磁脉冲下半导体器件内部的温度分布情况。从仿真结果可以看到,半导体器件在电磁脉冲作用下会产生严重的热效应,内部温度甚至能达到材料熔点。因而,在电子系统设计中必须采用相应的技术对半导体器件进行电磁防护。     

Evolutionary fuzzy SVR modeling of weld residual stress

Residual stresses are an integral part of the total stress acting on any component in service. It is important to determine and/or predict the magnitude, nature and direction of the residual stress to estimate the life of important engineering parts, particularly welded components. Researchers have developed many direct measuring techniques for welding residual stress. Intelligent techniques have been developed to predict residual stresses to meet the demands of advanced manufacturing planning. This research paper explores the development of Finite Element model and evolutionary fuzzy support vector regression model for the prediction of residual stress in welding. Residual stress model is developed using Finite Element Simulation. Results from Finite Element Method (FEM) model are used to train and test the developed Fuzzy Support Vector Regression model tuned with Genetic Algorithm (FSVRGA) using K-fold cross validation method. The performance of the developed model is compared with Support Vector Regression model and Fuzzy Support Vector Regression model. The proposed and developed model is superior in terms of computational speed and accuracy. Developed models are validated and reported. The developed model finds scope in setting the initial weld process parameters.     

NURBS-Enhanced Finite Element Method (NEFEM)

The development of NURBS-Enhanced Finite Element Method (NEFEM) is revisited. This technique allows a seamless integration of the CAD boundary representation of the domain and the finite element method (FEM). The importance of the geometrical model in finite element simulations is addressed and the benefits and potential of NEFEM are discussed and compared with respect to other curved finite element techniques.     

模型修正的正交模型-正交模态改进法

正交模型-正交模态法（CMCM）是一种参数修改的新方法,它具有不依赖于灵敏度分析、不需要进行迭代的特点.但是在有限元存在整体建模误差时,该方法会出现无法完成修正计算的情况,本文针对此问题进行了改进.改进后的方法可以既可以处理存在局部建模误差的情况,也可以处理存在整体建模误差的情况.本文通过梁式结构的数值算例,比较了原修正方法（CMCM）、改进后的修正方法（ICMCM）以及商业软件模型修正FEMtools的修正效果.结果表明：改进的正交模型-正交模态方法可以使分析频率更好地逼近实验值,物理参数的修改也更加准确.     

应变式多维力传感器结构优化设计方法研究

多维力传感器的结构决定了其精度及静、动态性能指标,对应变式多维力传感器弹性体结构耦合误差传递的原因进行了探讨,对比分析了传感器特性矩阵的目标优化函数的选择与优化方法、有限元法以及正交设计与极差分析法在传感器结构优化设计中的运用,提出了综合优化设计的思想,结合实例分析并阐述了该方法的实用性和有效性.     

有限元法在并行产品设计中的应用

文章研究了有限元法在并行产品设计中的应用,提出了典型产品的并行设计过程与方法,结合典型产品设计,研究了汽车车身并行虚拟样机方法。     

An evolutionary method for efficient computation of mutual capacitance for VLSI circuits based on the method of images

The problem of computing the capacitance coupling in Very Large Scale Integrated (VLSI) circuits is studied in this work. The proposed method is an approximate extended version of the method of images. The initial problem is formulated here as an optimization problem for the solution of which a genetic algorithm (GA) is employed. The proposed method is fast, general, does not rely on fitting techniques and is applicable to an arbitrary 2D or 3D geometry configuration of conductors. Extensive simulation results are presented for several practical case studies. Comparative results are given with other methods from literature and a commercial tool employing the Finite Element Method (FEM). The results show that the capacitance value computed by our method is in close agreement to the value obtained by the other methods from literature and also by the commercial tool with the average difference ranging between 2% and 5% while demonstrating better scalability as the problem complexity rises.     

基于全电极模式的三维电阻抗成像有限元法的算法实现

三维电阻抗成像(3D-EIT)技术是当今生物医学工程领域一项全新的研究课题,其中有限元法在EIT中的实现是EIT成像的基础。本文把有限元法用于3D-EIT中,利用全电极模式(CEM)详细推导了单元矩阵和总体矩阵,建立了相应的三维EIT有限元网格模型,并在计算机上运用Matlab7.0软件得以全部实现。     

Linear buckling analysis of thin-walled members combining the Generalised Beam Theory and the Finite Element Method

A finite element procedure to carry out linear buckling analysis of thin-walled members is developed on the basis of the existing Generalised Beam Theory (GBT) and constrained Finite Strip Method (cFSM). It allows designers to uncouple the buckling modes of a finite element model and, consequently, to calculate pure elastic buckling loads. The procedure can easily be applied to members with general boundary conditions subjected to compression or bending. The results obtained are rather accurate when compared to the values calculated via GBT and cFSM. As a consequence, it is demonstrated that linear buckling analyses can be performed with the Finite Element Method in a similar way as can be done with the existing GBT and cFSM procedures.