车身零件预装变形有限元虚拟评估分析

在车身工艺同步工程阶段,通过有限元仿真方法对车身制造过程中预装零件的不同产品设计方案进行虚拟评估分析,根据分析结果指导零件设计优化.该仿真方法在生产实物阶段得到验证,可提前识别制造过程质量风险.与传统的通过经验评估判断零件预装变形的方法相比,在工艺同步工程中应用有限元仿真技术,为解决车身制造过程中的复杂工况变形问题提供理论分析方法和依据,可靠性高,并达到缩短制造周期、降低制造成本的目的 .     

车身产品设计中的多层次尺寸链构建

尺寸偏差是影响汽车车身装配性能的一个主要因素,为了控制尺寸偏差,必须构建尺寸链模型以分析尺寸之间的相互复杂关系.以汽车车身设计为研究对象,分析了汽车车身装配的多层次、多等级特性;应用车身设计中的基准点系统和功能尺寸系统建立一种多级尺寸链模型,包括整车级、总成级、分总成级和零件级尺寸链.实例结构表明,所建立的多级装配尺寸链模型能使车身装配中的尺寸关系层次清晰化,并能对尺寸关系进行优化,使极为烦琐复杂的车身尺寸分析、偏差设计能有条不紊地逐步进行,为车身设计与制造改善找到了一条切实可行的路径.     

矢量化在车身CAD技术中的应用研究

本文研究了在车身内外覆盖件及其模具设计制造过程中遇到的由二维产品图纸建立三维CAD模型的问题，提出了应用矢量化和三维造型技术，实现由二维产品图建立三维CAD模型的原型系统，利用该系统，完成了若干实际工作。实践表明，本文提出的方法和原型系统对于解决由二维模型建造三维模型问题是非常有效的。     

多目标轻量化的白车身隐式参数数值模拟

普通方法构建的白车身多目标轻量化设计模型存在精准度低、优化效果差的问题.通过隐式参数数值模拟方法,先对白车身构建隐式参数化模型,再通过非安全件轻量化优化设计和正面碰撞安全件轻量化优化设计实现白车身多目标轻量化.通过对该方法的性能优化验证及对比实验发现,经过多次迭代后,上述方法构建的白车身模型的精准度均大于90％,优化变化率大于8％.     

基于有限元分析的重型卡车车架铆钉应力精确计算法

针对某重型卡车在行驶过程中铆钉脱落的问题,提出基于有限元分析的车架及其连接铆钉应力计算方法．在对整体车架进行结构强度分析时,先用梁单元离散铆钉并进行线性分析,再对感兴趣的部分划分边界,建立详细的铆钉接触子模型,做非线性分析．通过施加边界条件和进行非线性求解,得到铆钉上详细的应力分布情况．由接触子模型计算得到的22颗铆钉应力值,符合重型卡车在行驶过程中铆钉脱落的实际情况,表明该方法切实可行．深入分析22颗铆钉的应力情况,给出重型卡车车架铆钉的非线性计算结果与线性计算结果的比例因数0．285（铆钉连接的板壳有应力集中处为0．35）,为解决同类问题提供简单易行的方法．     

装配式混凝土结构套筒灌浆连接偏差仿真

为有效监测装配式混凝土结构套筒灌浆连接质量,针对装配式混凝土结构套筒灌浆连接偏差展开仿真.以单独套筒制备A组两个试件A1、A2,以混凝土和套筒制备B组两个试件B1、B2,在各试件相同位置粘贴压电片,并选用均方根(RMS)、均方根偏差(RMSD)及协方差(Cov)作为评估套筒灌浆饱满度缺陷的指标进行仿真,仿真中,运用压电阻抗技术采集各试件压电片五种灌浆工况下的电导信号,依据所采集的电导信号运算出各试件压电片电导的Drms值、RMSD值与Cov值,通过运算结果得出,B1试件的实际灌浆饱满度最高,A1试件的实际灌浆饱满度最低,B1试件的套筒灌浆连接偏差最小,A1试件的套筒灌浆连接偏差最大.     

车身设计尺寸质量评价的装配尺寸链自动生成

提出一种适合计算机推演的车身尺寸链生成方法．在研究装配有向图表达基础上建立车身装配接触链模型，并应用图论方法开发了以关键尺寸为目标的路径搜索算法；通过可行路径和尺寸链的映射关系，生成车身装配尺寸链．该方法的实现，有助于建立计算机辅助的车身柔性件尺寸质量评价系统。     

汽车车身CAD/CAM系统中曲面片光滑连接方法的研究

本文根据相容性一般条件,建立了曲面片沿U、V双向光滑连接的控制顶点调整方程,对方程的性质进行了讨论;建立了曲面单向光滑连接的升阶连接条件;在此基础上,提出适合于汽车车身曲面片光滑连接的四种基本形式及实现方法.     

基于弹塑性变形的快速展平算法与网格参数化

针对复杂CAD模型的展平问题,提出在三角网格上数值模拟汽车覆盖件一步逆成形的优化算法,实现了对车身零件毛坯料的快速估计.首先对初始网格进行补洞与局部重新网格化等预处理,得到辅助网格;为了减少变形,采用基于能量释放的初始解预示算法,并用基于金属板材弹塑性变形的一步逆算法进行迭代优化,得到修正的展平网格,经后处理得到最终参数化结果.将文中算法应用到自由边界网格参数化上,通过大量数值实验和比较结果表明,该算法不仅适用于工业上的坯料预估,而且在网格参数化的面积、扭曲变形方面有明显改善,同时具有较好的保角效果.     

用CATIA运动模拟分析汽车内饰摆轮机构运动

目前汽车行业竞争越来越激烈,客户希望在尽量合理的价格内、较短的时间里完成最好的产品。其中汽车内饰功能件,由于会在客户驾乘时使用,影响着整车的质量、舒适性和豪华度,是客户选择汽车时的重要因素。本文讨论的内饰摆轮机构件多用于内饰储物盒、烟灰缸等功能件中,用来实现PUSH-PUSH开闭盒体的功能。因该类零件运动大多较为复杂,分析困难,本文介绍在CATIA中模拟该类运动,解决实际问题的方法。     

Worst-Case Simulation of Discrete Linear Time-Invariant Interval Dynamic Systems

In this paper, a new approach to worst-case simulation of discrete linear time- invariant interval dynamic systems is proposed. For stable systems, the new approach solves the problem of worst-case simulation by determining the interval hull enclosing the system states region at every iteration through optimisation. The originality of this approach is that it maintains time-invariant parametric uncertainties during the simulation process. Several previous algorithms have considered the case of parametric time-varying uncertainties (El Ghauoi, L., Calafiore, G.: Worst-Case Simulation of Uncertain Systems, in: Garulli, A., Tesi, A., and Vicino, A. (eds), Robustness in Identification and Control, Springer, London, 1999). However, Cuguer' o (Avoiding Possible Instability in Robust Simulation of Stable Parametric Uncertain Time-Invariant Systems, in: Proceedings of 40th Conference on Decision and Control, Florida, 2001) has presented possible instability problems when simulating a time-invariant uncertain system as if it were time-varying, this result being the motivation for the approach proposed in this paper. The optimisation problem associated with the approach proposed must be solved globally in order to guarantee that the minimum volume box enclosing the region of system states has been derived. In this paper, a global optimisation algorithm based on an interval branch and bound strategy is proposed. Finally, two real application examples are used to test the performance of the approach proposed.     

Demand-driven logic simulation using a network of loosely coupled processors

Logic simulation is used extensively in the design of digital systems for the purpose of studying the behaviour of circuits under various conditions and for verifying the required performance of circuits. There is considerable interest in methods which reduce the simulation time during the design process. In this paper, we investigate how this can be achieved by simulating the action of logic circuits using a network of loosely coupled processors. Circuits modelled as directed graphs comprising clocked sequential components and (unclocked) arbitrary combinational logic gates can be partitioned into separate tasks each consisting of a sequential component with an associated network of combinational components. We present cost functions for evaluating a task subject to probabilistic assumptions about the functioning of the circuits. The circuit evaluation method used in the simulation process is significant. We apply lazy evaluation, a demand-driven evaluation strategy in which signals in the circuit are evaluated on a ‘need to do' basis, resulting in a considerable saving in circuit simulation time. We achieve distributed logic simulation using a network of workstations and show from experimental results that by using such a configuration, we essentially obtain a single computation engine which can be used to obtain speedups in circuit simulation when compared with uniprocessor simulation systems. Interprocess communications between tasks on different workstations proceed via remote procedure calls while local communications between tasks take place via shared memory. The method of partitioning used in the circuit model ensures that communications between tasks take place only at defined times in the simulation sequence.     

V850E/MS1嵌入式处理器的实现

针对嵌入式系统软件的开发效率问题,通过对V850E/MS1体系结构建模研究,提出并实现一个高效的指令集模拟器V850E/MS1- sim,该模拟器主要由指令集系统、内存管理、终端系统和外设接口组成,采用指令集模拟和串行模拟的方法。仿真实验结果表明,V850E/MS1-sim在保证模拟精确性的同时,提高了模拟效率。     

Simulation of impact, based on an approach to detect interference

This paper describes a method for simulating impacts which occur during the motion of planar mechanisms. An interference detection method is proposed. Using this, distance between bodies can be determined during simulation, without having to solve a system of nonlinear equations. The approach is illustrated by simulating a cam–follower mechanism. Impact is modelled using nonlinear compliance at the point of contact, and friction is modelled as Coulomb’s friction. Numerical integration is partially validated using energy balance.     

The kernel density estimate/point distribution model (KDE-PDM) for statistical shape modeling of automotive stampings and assemblies

The ability to effectively model dimensional variation of stampings and assemblies is an important tool for manufacturers to investigate, assess and control quality levels of their products. Statistical Process Control (SPC) and Six-Sigma approaches use the assumptions of statistical independence and normally distributed data to create quality process control guidelines which are predominantly used in industry. Multivariate statistical techniques such as Principal Components Analysis (PCA) have been more recently applied to automotive body assembly analysis in order to capture the surface co-linearity present in the dimensional variation of stampings and assemblies. This paper combines the Point Distribution Model, which is based on PCA, and Kernel Density Estimation to provide a statistical shape model (the KDE–PDM) that can deal with high dimensional data sets, represent correlated variation modes, and provide accurate estimates of the underlying shape distribution. Examples from FE simulation and production case studies are presented to highlight the advantages of the KDE–PDM over two other statistical shape models: the univariate shape model, and the original PDM. The KDE–PDM's capabilities make it particularly suited to variation monitoring and diagnosis of high dimensional measurement data sets made available by optical measurement devices, and some suggestions for its implementation are also presented.     

物流车辆监控系统建模与仿真

物流的运输系统常常需要考虑交通堵塞、路径选择、能源危机、成本控制等各种复杂因素，对物流车辆调度人员提出了很高的要求，因此该文提出建立物流车辆监控仿真系统来模拟物流运输过程中对车辆实时动态的调度。该文结合GIS／GPS／GSM车辆监控系统的工作原理，设计了物流车辆监控系统模型，并构建了基于HLA（High Level Architecture）的物流车辆监控仿真系统框架。从应用的角度分析了HLA仿真开发过程，初步实现物流车辆监控模拟系统联邦，为车辆调度员进行教学和培训提供了一个模拟现实的环境，对物流车辆监控系统的实现起到了一定的辅助作用。     

Using a simulation model for knowledge elicitation and knowledge management

The work reported in this paper is part of a project simulating maintenance operations in an automotive engine production facility. The decisions made by the people in charge of these operations form a crucial element of this simulation. Eliciting this knowledge is problematic. One approach is to use the simulation model as part of the knowledge elicitation process.This paper reports on the experience so far with using a simulation model to support knowledge management in this way. Issues are discussed regarding the data available, the use of the model, and the elicitation process itself.     

Modelling and simulation of forming process of the lithographically fabricated out-of-plane microlens using a cellular automata method

Three dimensional (3D) cellular automata (CA) model has been successfully applied in photoresist etching simulation in recent years. In this paper, a simplified 3D CA model is used to simulate the etching process of out-of-plane microlens fabricated on thick SU-8 photoresist. The simulation results are compared with experimental results. This CA model can be developed as a computer-aided design tool to predict the optimum process parameters during the forming of lithographically fabricated microlens.     

MATLAB在模型参考模糊自适应控制系统仿真中的应用

该文详细介绍了用MATLAB（SIMULINK）语言对模型参考模糊自适应控制（MRFAC）系统进行仿真的步骤和方法，可以看出SIMULINK工具箱是控制系统动态仿真的有力工具，而且相对于以往任何一种仿真方法，MATLAB语言更方便，高效，具有无可比拟的优越性。     

电子对抗的仿真与实现

针对无线电引信与电子干扰机之间的电子对抗，探讨了对其进行计算机仿真的原理和实现方法。在此基础上，构建了一个实际的电子对抗仿真系统。该系统可以在实验室条件下模拟与实际战斗情况相仿的战斗环境和战斗过程，对引信与干扰机之间的电子对抗过程进行仿真、测试并记录引信与干扰机的工作情况。最后以动画仿真的方式在计算机上实现了引信与干扰机之间电子对抗的仿真。