LiToTac: An Interactive-Interface Software for Finite Element Analysis of Multiple Contact Dynamics

In order to investigate the mechanical behavior of systems with complex architecture and a large number of contacting bodies,a finite element software,named LiToTac,has been developed by using the object-oriented programming technique.This software,with an interactive graphical user interface,is able to handle highly non-linear problems including multiple contacts and large deformation.More importantly,the contact detection based on a hybrid three-stages methodology can be performed automatically,which is more efficient than the common strategies of pre-defining contact zones in commercial FEM software like ANSYS,ABAQUS,etc.In addition,the contact solver in LiToTac is portable between dynamic and quasi-static codes and can accurately solve contact coupled with friction in a reduced system.Several numerical examples are carried out to illustrate the functionality and capacity of the software package.

High-efciency improved symmetric successive over-relaxation preconditioned conjugate gradient method for solving large-scale finite element linear equations

Fast solving large-scale linear equations in the finite element analysis is a classical subject in computational mechanics. It is a key technique in computer aided engineering （CAE） and computer aided manufacturing （CAM）. This paper presents a high-efficiency improved symmetric successive over-relaxation （ISSOR） preconditioned conjugate gradient （PCG） method, which maintains lelism consistent with the original form. Ideally, the by 50% as compared with the original algorithm. the convergence and inherent paralcomputation can It is suitable for be reduced nearly high-performance computing with its inherent basic high-efficiency operations. By comparing with the numerical results, it is shown that the proposed method has the best performance.

Finite element based design of software for integrated passive and active vibration control

Presents the design scheme developed for design of software for Integrated Passive and Active Vibration Control(IPAVC) and the coding of a prototyne system, and the selection of the famous finite element program MSC/NASTRAN as an important module of software to deal with large and complicated structures and systems with an example to demonstrate the prototype system.

Research of the Higher-order Finite Element Arithmetic for Radiation Exchange

With the development of aeronautic and astronautic techniques, radiation becomes much more significant while the structure is exposed to the higher and higher temperature. Most of the current finite element software packages treat it using the net-radiation method or absorbed radiation method based on the assumption of isothermal surface with uniform radiation heat flux, which brings the conflict between the precision and the quantity of grids. Using integral method to compute the variable radiation heat flux in higher-order finite element, the precision can be improved greatly while using the same quantity of grids, because it is more consistent with the distribution of real temperature. In this paper, the integral is only processed on the same integral points as those used for solving the finite element equations, so it may be of high efficiency. In an academic testing model, the result is contrast to which get in ANSYS, proving the high precision of the method. Then an actual sandwich panel used in the thermal protection system is analyzed with the method, and the error is comparatively low to the analytical answer while the computation being of high efficiency.

Experimental research and finite element analysis of bridge piers failed in flexure-shear modes

In recent earthquakes, a large number of reinforced concrete （RC） bridges were severely damaged due to mixed flexure-shear failure modes of the bridge piers. An integrated experimental and finite element （FE） analysis study is described in this paper to study the seismic performance of the bridge piers that failed in flexure-shear modes. In the first part, a nonlinear cyclic loading test on six RC bridge piers with circular cross sections is carried out experimentally. The damage states, ductility and energy dissipation parameters, stiffness degradation and shear strength of the piers are studied and compared with each other. The experimental results suggest that all the piers exhibit stable flexural response at displacement ductilities up to four before exhibiting brittle shear failure. The ultimate performance of the piers is dominated by shear capacity due to significant shear cracking, and in some cases, rupturing of spiral bars. In the second part, modeling approaches describing the hysteretic behavior of the piers are investigated by using ANSYS software. A set of models with different parameters is selected and evaluated through comparison with experimental results. The influences of the shear retention coefficients between concrete cracks, the Bauschinger effect in longitudinal reinforcement, the bond-slip relationship between the longitudinal reinforcement and the concrete and the concrete failure surface on the simulated hysteretic curves are discussed. Then, a modified analysis model is presented and its accuracy is verified by comparing the simulated results with experimental ones. This research uses models available in commercial FE codes and is intended for researchers and engineers interested in using ANSYS software to predict the hysteretic behavior of reinforced concrete structures.

Simulated Experiments for Teaching Mutually-Coupled Circuits CAD Techniques Using Analytic and Finite Element Solutions

The paper describes an approach to teaching mutually-coupled circuits CAD techniques to undergraduate students pursuing a degree course in electrical engineering or physics, and explains how a series of simulated experiments may be incorporated into the existing subjects. The simulated experiments make use of a two-dimensional open-access software based on the finite-element method. At the laboratory meetings, the students learn how to set up field problems for solution, and how to examine the results. Simulation tasks based on three axisymmetric open-boundary problems are used to introduce different numeric techniques to compute inductance and magnetic forces. The paper takes the reader to a step-by-step simulation journey, and provides all the basic elements required for further exploration of axially-symmetric systems.

Design of Finite Element Tools for Coupled Surface and Volume Meshes

Many problems with underlying variational structure involve a coupling of volume with surface effects.A straight-forward approach in a finite element discretiza- tion is to make use of the surface triangulation that is naturally induced by the volume triangulation.In an adaptive method one wants to facilitate'matching'local mesh modifications,i.e.,local refinement and/or coarsening,of volume and surface mesh with standard tools such that the surface grid is always induced by the volume grid. We describe the concepts behind this approach for bisectional refinement and describe new tools incorporated in the finite element toolbox ALBERTA.We also present several important applications of the mesh coupling.

Performance Comparisons of Programs in Different Programming Languages Converted from Legacy Finite Element Codes

The FORTRAN programming language was used in early days of writing finite element field computation to write programs Much of those codes were developed in an ad hoc way. Today, modem software developers face problems in understanding, modifying and utilizing those codes. As modem software engineers are very concerned with object oriented design, if those codes are converted into an object oriented language, they could be redesigned and deployed in an object oriented system. Those legacy codes often need to be converted not only into an object oriented programming language such as Java but also into functional oriented languages such as C. Conversion of those legacy codes into modem languages gives many advantages. The purpose of this paper is to compare the performances of such converted legacy finite element codes originally written in FORTRAN, the relevant converted C program and Java program. Sample finite element programs written in FORTRAN are converted for purposes of comparison into modem languages such as C and Java. Performances are compared based on the execution time. In addition to that, the memory sizes of the execution file of FORTRAN and C programs are also compared. Java being interpretive there is no execution file to compare.

Finite Element Analysis of the Dynamic Behaviour of Transmission Line Conductors Using MATLAB

The dynamic behaviour of power line cables have been a source of interest to researchers ever since the phenomenon was first noticed in the 1920s. Conductor oscillation is mostly caused by the dynamic forces of nature such as wind loading. This imposes a periodic force on the conductors which is highly undesirable. It is therefore important for engineers to account for the possible effect of the wind loading when designing the power line. Investigations have shown that modeling the exact dynamic behaviour of a conductor is very difficult. Based on this fact, getting the exact analytical solution to conductor vibration is difficult, which is almost impossible, hence the numerical approximation becomes an option. This paper presents the developed finite element method used to analyse the dynamic behaviour of transmission line conductors. The developed FEM （finite element method） is implemented on MATLAB. The numerical analysis using MATLAB that is presented in this paper is used to simulate the response of the conductor when subjected to external loading in the time domain. The simulation is used to analyse the transverse vibration of the conductor. The formulation of the stiffness matrix and load vector is done and the results obtained are used to evaluate the conductor＇s internal energy dissipation. This finite element solution is compared with the results documented in literature. This numerical simulation is also used to investigate the effects of varying the axial tension on energy dissipation within the strands. Hence, this evolved in physically appropriate energy characterization process that can be used to evaluate the conductor self-damping with respect to line contact.

Analysis of Demagnetizer Operation Using the Finite Element Method

Permanent magnets with high energy products are widely used in a variety of electromagnetic devices. Such devices can be found in marine, aerospace, and robotic applications which require the minimization of weight and volume of the electromagnetic device. During the magnetizing process, the magnet may not be perfectly magnetized. Therefore, it needs to be demagnetized. Because of high coercivity of some permanent magnets, the demagnetization process requires the intense magnetic fields in close proximity with the magnetic material. The fields must be produced for a short period of time （millisecond range） and they also must be bidirectional in order to overcome the coercivity of magnetic material. Different parameters have been known to affect the demagnetizer operation such as the core shape, core material, turn number, cross section of air gap, magnet type and so on. The amplitude and waveform of the fixture current is obtained from PSPICE simulations and also from experimental measurement. A 2D finite element analysis is developed to simulate the magnetic fields and the mechanical forces. In this paper, the main parameters affecting the optimal design of the demagnetizer are discussed. Simulation results show that the core structure, air gap width, and turn numbers are the most important parameters when designing such a device.

3-D Finite-Element Numerical Simulation of Centrifugal Induction Electrosalg Casting Solidification Process

A 3-D finite-element numerical simulation model of temperature field for CIESC casting solidification process was developed with the aid of ANSYS software and a series of corresponding experiments were made. The results showed that the good agreement was obtained between the numerical simulation and the experiments. Based on the numerical simulation results, the characteristics of temperature distribution in the castings during CIESC solidification process were analyzed and summarized. According to the G/R-1/2 method and numerical simulation results, there is no any shrinkage defect in the CIESC casting and structure or casting is fine and compact.

Simulation of large-scale numerical substructure in real-time dynamic hybrid testing

A solution scheme is proposed in this paper for an existing RTDHT system to simulate large-scale finite element （FE） numerical substructures. The analysis of the FE numerical substructure is split into response analysis and signal generation tasks, and executed in two different target computers in real-time. One target computer implements the response analysis task, wherein a large time-step is used to solve the FE substructure, and another target computer implements the signal generation task, wherein an interpolation program is used to generate control signals in a small time-step to meet the input demand of the controller. By using this strategy, the scale of the FE numerical substructure simulation may be increased significantly. The proposed scheme is initially verified by two FE numerical substructure models with 98 and 1240 degrees of freedom （DOFs）. Thereafter, RTDHTs of a single frame-foundation structure are implemented where the foundation, considered as the numerical substructure, is simulated by the FE model with 1240 DOFs. Good agreements between the results of the RTDHT and those from the FE analysis in ABAQUS are obtained.

Large-scale two-dimensional nonlinear FE analysis on PGA amplification effect with depth and focusing effect of Fuzhou Basin

Based on the explicit finite element(FE) method and platform of ABAQUS,considering both the inhomogeneity of soils and concave-convex fluctuation of topography,a large-scale refined two-dimensional(2D) FE nonlinear analytical model for Fuzhou Basin was established.The peak ground motion acceleration(PGA) and focusing effect with depth were analyzed.Meanwhile,the results by wave propagation of one-dimensional(1D) layered medium equivalent linearization method were added for contrast.The results show that:1) PGA at different depths are obviously amplified compared to the input ground motion,amplification effect of both funnel-shaped depression and upheaval areas(based on the shape of bedrock surface) present especially remarkable.The 2D results indicate that the PGA displays a non-monotonic decreasing with depth and a greater focusing effect of some particular layers,while the 1D results turn out that the PGA decreases with depth,except that PGA at few particular depth increases abruptly; 2) To the funnel-shaped depression areas,PGA amplification effect above 8 m depth shows relatively larger,to the upheaval areas,PGA amplification effect from 15 m to 25 m depth seems more significant.However,the regularities of the PGA amplification effect could hardly be found in the rest areas; 3) It appears a higher regression rate of PGA amplification coefficient with depth when under a smaller input motion; 4) The frequency spectral characteristic of input motion has noticeable effects on PGA amplification tendency.

Software development of modeling assistant for continuous suspension bridges with multi-pylon

Building a reasonable and accurate finite element model is the first and critical step for structural analysis of complicated bridge. In this article, modeling assistant for continuous suspension with multi-pylon is developed based on .Net platform, with VB.Net, C# language and OpenGL graphic technique. With parameterized modeling method, finite element model of this kind of bridge can be built quickly and accurately, and multi-type element modeling with uniform parameters is realized. With advanced graphic technique, three-dimensional model graph can be real-timely previewed for intuitive data check. With an example of practice project, the accuracy and feasibility of this modeling method and practicality of this software are verified.

A Generic Computational Solution of a Natural Convection Flow past an Infinite Vertical Porous Plate

A simulation was carried out on an unsteady flow of a viscous, incompressible and electrically conducting fluid past an infinite vertical porous plate. A generic computer program using the Galerkin finite element method is employed to solve the coupled non-linear differential equations for velocity and temperature fields. The diffusion equation, the energy equation, the momentum equations and other relevant parameters are transformed into interpretable postfix codes. Numerical calculations are carried out on the flow fields both in the presence of cooling and heating of the plate by free convection currents. The effects of the dimensionless parameters, namely, the Prandtl number, the Eckert number, the modified Grashof number, the Schmidt number and the time on the temperature and velocity distributions are discussed.

ANSYS和ADAMS在菌落挑取机器人结构设计中的运用

针对现有菌落挑取机器人挑取速度低、集成自动化程度低、挑针重复利用率低等问题,设计出一种多针同时操作的转盘式挑取机器人。首先,为保证主要受力部件(气缸安装版与转盘)的应力、应变在误差范围内,运用有限元分析软件ANSYS Workbench分别对其校核了Z轴定位精度和平面定位精度,由静力学分析结果确定其强度可靠且精度满足设计要求,准确挑取;其次,为保证菌落挑取过程平稳,利用仿真软件ADAMS对菌落分度挑选机构(弧面分度凸轮)进行动力学分析,研究分度挑选机构的动态特性及其运动规律,发现各运动参数的仿真结果与理论相吻合,保证新型机器人在挑取过程中可以避免冲击和振动的发生。该结果表明:挑取机构的强度、刚度及运动的平稳性均满足要求,有效验证了设计的合理性。

有限元及工程软件课程思政探索及实践

有限元及工程软件是力学及相关专业重要的研究生专业核心课之一,已成为工程设计分析和科学研究中物理过程建模的重要计算工具。在课堂教学过程中加强课程思政,是高校提高人才培养质量的有效途径,对培养具有很强专业素质的“四有”新人具有重要意义。为加强有限元及工程软件的课程思政教学,根据课程内容及特点分析课程思政的必要性,确定课程思政目标,给出课程思政内容的教学设计,使课程内容与课程思政元素有机融合,同时探讨课程思政的教学实践方案,可为专业课程的课程思政教学提供借鉴。

基于有限元自主仿真软件的教学创新研究

随着数字化建设的不断推进,计算机辅助工程(Computer Aided Engineering, CAE)在各领域的应用也愈发广泛,将CAE仿真技术引入课堂,以数字化教学模式培养新时代具有创新能力的复合型人才已经成为教育发展的必然趋势。国外商用有限元仿真软件存在操作烦琐,无仿真基础学生一时难以上手等问题。国产自主开发的有限元仿真软件配有众多应用接口,凭借其操作简单、功能完善等优势脱颖而出,为CAE仿真与课堂教学的结合注入全新的活力。

电工装备低频电磁仿真中若干关键问题研究现状及趋势

低频电磁场仿真是电气装备智能化的基础核心技术。该文基于计算电磁学自20世纪60年代以来的发展历程,讨论了低频电磁场仿真中若干关键问题的发展现状,展望了当前数值仿真领域的发展趋势。首先,介绍了低频电磁场计算基本方程及数值离散方法;其次,对低频电磁场计算中材料建模的均一化、各向异性、磁滞模型等方面开展了分析和探讨;随后,针对空间多尺度、趋肤效应、开放边界以及变形与运动对低频电磁场仿真中网格和离散格式的特殊性进行了阐释,分析了当前电磁-力-热多物理耦合中的关键问题,介绍了数字孪生模型构建中基于物理模型和数据驱动的建模方法及近期工作;最后,对数值仿真在优化设计、人工智能、新一代仿真软件等方面的发展趋势进行了分析和展望。当前,多尺度多物理耦合建模仿真方法仍是电磁场计算领域的研究重点。传统数值仿真与新兴计算技术、人工智能的结合愈加紧密。智能制造和数字孪生等前沿需求下,电磁场计算面临高效迭代仿真和实时仿真的挑战,由物理模型和数据共同驱动的替代建模是解决这两方面挑战的重要手段。工业CAE仿真软件架构正在发生着深刻变革,迫切需要我国自主CAE仿真软件核心技术及应用生态的提升。