CAE在汽车座椅轻量化设计中的应用

以汽车座椅靠背为研究对象,利用材料力学原理分别设计3种不同截面形状的钢制座椅靠背圆钢管,基于Hyper Works有限元软件对3种方案进行静强度模拟分析,运用密度法对新型铝合金座椅骨架进行拓扑优化设计。结果表明：截面为椭圆型的钢管比等截面面积的圆形钢管具有更大的抗弯强度,拓扑优化是一种有效的结构概念设计方法,使铝合金座椅靠背质量减轻16．5％,从结构和材料2方面实现了汽车座精轻量化的目的。     

基于水平集描述的结构拓扑与构件布局联合优化新方法

该文提出了一种结构拓扑与内嵌构件布局联合优化的新颖方法。这种方法突出的特点是利用水平集函数隐式地描述不规则的构件形状,因此可以非常方便地处理构件之间的互不覆盖约束条件。数值算例表明：较之文献中已有的方法,该文算法能够以更小的计算量有效地实现结构拓扑与内嵌构件布局的联合优化。     

汽车动力总成悬置骨架的拓扑优化设计

以某商用车动力总成的悬置骨架为分析对象,基于变密度法建立拓扑优化的数学模型及其求解方法;运用有限元软件Hyperworks中的Optistruct模块将拓扑优化方法应用到该商用车动力总成的悬置骨架结构设计中,对单工况下的骨架结构进行优化设计。根据优化的结果并结合生产经验,设计出新悬置骨架的结构。最后用ABAQUS软件对悬置总成进行应力、变形和体积的计算。结果表明,经过优化的悬置骨架安全性能得到提高,重量减轻。     

汽车座椅造型设计分析

通过对汽车座椅造型设计因素的分析,提出在进行汽车座椅造型时所需要解决的问题,以帮助设计师在设计中快速准确地确定目标进行调查和问题的分析,从而使汽车座椅的造型设计更加有效,为企业和设计师提供分析资料和理论支撑。     

考虑结构稳定性的变密度拓扑优化方法

将稳定性问题引入传统变密度法中,可实现包含稳定性约束的平面模型结构拓扑优化。以单元相对密度为设计变量,结构柔度最小为目标函数,结构体积和失稳载荷因子为约束条件建立优化问题数学模型,提出了一种考虑结构稳定性的变密度拓扑优化方法。通过分析结构柔度、体积、失稳载荷因子对设计变量的灵敏度,并基于拉格朗日乘子法和Kuhn-Tucker条件,推导了优化问题的迭代准则。同时,利用基于约束条件的泰勒展开式求解优化准则中的拉格朗日乘子。通过推导平面四节点四边形单元几何刚度矩阵的显式表达式,得到了优化准则中的几何应变能。最后,通过算例对提出的方法进行了验证,并与不考虑稳定性的传统变密度拓扑优化方法进行对比,结果表明该方法能显著提高拓扑优化结果的稳定性。研究结果对细长受压结构的优化设计有重要指导意义,对结构的稳定性设计有一定参考价值。     

空间反射镜轻量化结构的拓扑优化设计

为满足较高面形要求,实现空间反射镜的高度轻量化设计,在直径500 mm 圆反射镜的设计过程中引入拓扑优化方法.依据变密度法建立SIMP模型,在反射镜光轴方向重力的工况下,以结构整体柔度为设计约束,最小体积为设计目标,经过选代,得到了RMS值小于5nm,轻量化率达到75.83%的结构.在同等质量下,传统的三角形孔轻量化结构的RMS值为8.17nm,轻量化率为67.39%.并对优化后的结构与三角形轻量化结构在径向重力工况下进行了面形对比,计算结果满足设计要求.拓扑优化的轻量化方式在面形和轻量化率上都优于传统形式.     

桁架结构智能布局优化设计

结构的布局优化由于涉及尺寸、形状和拓扑三个层次的综合设计而成为优化问题中的难点,结合桁架结构提出了一个基于多个初始基结构的布局优化方法。以智能生成的、型式多样合理的基结构代替传统模型中的单一基结构,然后从不同基结构下的拓扑优化结果中找出最优设计。在克服传统基结构法有可能限制求解空间而丢失最优解这一局限性的同时,将形状和拓扑优化设计有效分离,降低了求解的难度,并且结合拓扑变化法,实现了桁架结构从选型生成、分析计算到优化设计的一体化智能设计过程。算例表明:利用该文提出的方法进行桁架结构的最优布局设计是可靠有效的。     

基于模糊PID控制的汽车座椅测试系统的设计

汽车座椅静载强度的测试直接关系到乘员的人身安全,其测试系统要求控制精度高,超调量小以及稳态误差小。传统的PID控制由于参数整定差,不能满足汽车座椅测试系统高精度的要求。本文将模糊控制与PID控制结合起来,设计了模糊PID控制器。通过MATLAB/Simulink对控制器的仿真分,比较传统控制和模糊PID控制的性能,验证模糊PID控制器的优越性。最终试验结果表明:模糊PID控制系统的超调量在3%以内,稳态误差在0.7%以内,具有较高的控制精度,符合测试要求。     

基于拓扑优化的结构加强筋布局降噪方法研究

基于变密度拓扑优化方法,提出了通过优化加强筋布局来降低谐振结构辐射声功率的策略。优化中将加强筋单元的伪密度作为设计变量,约束为加强筋质量上限,所用寻优算法为移动渐近线(MMA)系列算法中的MMA-GC-MMA混合算法。对结构的振动响应使用有限元方法求解,对声辐射使用边界元方法求解,并在此基础上分析了目标函数对设计变量的灵敏度。以加筋箱体为例进行优化,验证了所提方法在降噪设计中的可行性和有效性,并对结果进行了讨论。     

结构拓扑优化的发展及其模型转化为独立层次的迫切性

回顾了结构拓扑优化的发展过程,叙述了结构拓扑优化的研究现状,阐述了各种常用的拓扑优化方法。结合作者在结构拓扑优化方面的研究工作,介绍了ICM(独立、连续、映射)方法,并通过连续结构和离散结构的典型数值算例说明了将结构拓扑优化的模型转化为独立层次进行研究的迫切性和重要性。     

Integrated layout design of multi‐component system

A new integrated layout optimization method is proposed here for the design of multi‐component systems. By introducing movable components into the design domain, the components layout and the supporting structural topology are optimized simultaneously. The developed design procedure mainly consists of three parts: (i) Introduction of non‐overlap constraints between components. The finite circle method (FCM) is used to avoid the components overlaps and also overlaps between components and the design domain boundaries. (ii) Layout optimization of the components and supporting structure. Locations and orientations of the components are assumed as geometrical design variables for the optimal placement while topology design variables of the supporting structure are defined by the density points. Meanwhile, embedded meshing techniques are developed to take into account the finite element mesh change caused by the component movements. (iii) Consistent material interpolation scheme between element stiffness and inertial load. The commonly used solid isotropic material with penalization model is improved to avoid the singularity of localized deformation in the presence of design dependent loading when the element stiffness and the involved inertial load are weakened by the element material removal. Finally, to validate the proposed design procedure, a variety of multi‐component system layout design problems are tested and solved on account of inertia loads and gravity center position constraint. Solutions are compared with traditional topology designs without component. Copyright © 2008 John Wiley & Sons, Ltd.     

桁架结构布局优化的并行子空间方法

由于结构布局优化存在设计变量类型众多和变量耦合等问题,采取合适的优化方法获得满足结构设计要求的最小质量的结构具有重要的工程意义.基于多学科设计优化方法中的并行子空间优化法,提出一种桁架结构布局优化的并行子空间优化方法.将结构布局设计问题按设计变量类型分为布局、形状和尺寸三个并行的子空间,设计变量在各自的子空间内单独优化,各子空间优化结束后,在系统级中协调3类设计变量,保持最小质量的子空间的优化设计变量不变,采用近似一维搜索的方法协调其他子空间的设计变量,然后进行下一次迭代直至收敛.2个算例表明该方法能够取得较好的优化结果,具有实际工程应用价值.     

Computational evaluation of automotive camber component for light-weight design

Due to global warming, environmental issues are one of the most interesting issues in the world. Especially for automobiles that emit pollutants, the issue of lightweight design is one of the important research areas. Thus, this study deals with the lightweight design of a camber link, an automotive suspension component, through finite element analysis. With reference to the camber link made of steel (SM45C) material that has been proven by commercialization, we will replace it with A356 aluminum alloy material to reduce the weight. Here, the design was changed through finite element analysis to reinforce the reduction of rigidity due to material substitution. In particular, we propose a method of designing a camber link considering the safety factor by analyzing the change of stress applied to the suspension. The weight reduction of about 14 % was achieved through static analysis using the weight factor. Using the dynamic optimization method through static analysis using the weight factor and stress ratio, it can be seen that the application is convenient and easy for the lightweight and optimal design of automobile parts.     

Finite-element analysis and structural optimization design study for cradle seat of CNC machine tool

In order to improve the machining precision of the five-axis CNC machine tool, the cradle seat must have good structure and mechanical properties. Using the CAD/CAE-integrated design platform, static finite-element analysis and sensitivity analysis of the original cradle seat were conducted. Based on the above analysis, the weak part of the original cradle seat was discovered. A multi-objective optimization design process for the cradle seat’s weak part was carried out, and six groups of non-inferior solutions were obtained. From the six groups of optimization design schemes and the original design scheme, the optimal design scheme was selected using fuzzy matter-element method and the entropy-weight method. The cradle seat’s mass was reduced by 2.76%, and the maximum deformation was reduced by 27.38%. The impact test analysis results showed that the dynamic performance of the cradle seat, after optimization design, was greatly improved, which proves that the proposed structural optimization design method based on sensitivity analysis is reasonable and feasible.     

汽车电动座椅出厂位姿调整方法研究

为了解决多自由度汽车电动座椅出厂位姿调整过程中的耦合问题,消除座垫不规则表面对调整过程的影响,实现座椅位姿的快速调整,提出了一种基于控制变量法的座椅位姿调整方法。首先,根据座垫表面的拟合曲线和座椅的几何结构,建立参考坐标系并分析座椅外部轮廓上的点与当前运动关节的转角或位移之间的数学关系。然后计算出座椅的当前位姿并给出调整方案。最后,通过仿真和实验验证了所提方法的可行性。仿真和实验结果表明：该方法能够消除座垫不规则表面和关节耦合对调整过程的影响,同时能提高调整的准确度和效率。研究结果对改进汽车电动座椅出厂位姿调整方法和提高座椅调整效率有一定的参考意义。     

Finite-circle method for component approximation and packing design optimization

In this article, the finite-circle method is introduced for 2D packing optimization. Each component is approximated with a group of circles and the non-overlapping constraints between components are converted into simple constraints between circles. Three new algorithms—the bisection algorithm, the three-step algorithm, and the improved three-step algorithm with gap—are developed to automatically generate fewer circles approximating the components. The approximation accuracy, the circle number, and the computing time are analyzed in detail. Considering the fact that packing optimization is an NP-hard problem, both genetic and gradient-based algorithms are integrated in the finite-circle method to solve the problem. A mixed approach is proposed when the number of components is relatively large. Various tests are carried out to validate the proposed algorithms and design approach. Satisfactory results are obtained.     

舰艇武器布置问题的一种协同优化算法

针对舰艇武器布置问题的特点，提出了一种基于粒子群优化和分类器系统的协同优化算法，以粒子群优化进行优化计算，用分类器系统消除约束．计算实例表明，该算法能较好地实现优化计算，并能节省大量的计算时间．     

The constraints satisfaction problem approach in the design of an architectural functional layout

A design support system with a new strategy for finding the optimal functional configurations of rooms for architectural layouts is presented. A set of configurations satisfying given constraints is generated and ranked according to multiple objectives. The method can be applied to problems in architectural practice, urban or graphic design—wherever allocation of related geometrical elements of known shape is optimized. Although the methodology is shown using simplified examples—a single story residential building with two apartments each having two rooms—the results resemble realistic functional layouts. One example of a practical size problem of a layout of three apartments with a total of 20 rooms is demonstrated, where the generated solution can be used as a base for a realistic architectural blueprint. The discretization of design space is discussed, followed by application of a backtrack search algorithm used for generating a set of potentially ‘good’ room configurations. Next the solutions are classified by a machine learning method (FFN) as ‘proper’ or ‘improper’ according to the internal communication criteria. Examples of interactive ranking of the ‘proper’ configurations according to multiple criteria and choosing ‘the best’ ones are presented. The proposed framework is general and universal—the criteria, parameters and weights can be individually defined by a user and the search algorithm can be adjusted to a specific problem.     

System for computer-aided cavity layout design for die-casting dies

Die-casting is one of the methods used to produce a large number of components with a good surface finish by injecting cast alloys into a metal mould under high pressure. The design of a die-casting die requires human expertise and is normally performed by trial and error, which leads to monetary and time losses. Automation at the initial die design stage would result in higher productivity and would reduce the production lead time. Decisions regarding the number of cavities, the layout pattern and the placement of cavities in die-casting are critical for die design and manufacturing. This paper presents research work on a system for computer-aided cavity layout design for die-casting dies. The proposed system consists of three modules: (1) determination of number of cavities; (2) selection of layout pattern; and (3) placement of cavities in the die base. It enables die designers to generate a cavity layout design automatically from a computer-aided design (CAD) file of the part with little information provided manually. The optimal number of cavities is determined by considering economic, technical, geometrical and time limitations, followed by the selection of a layout pattern. Thereafter, cavities are placed in the die base. The developed system depends on a database of die-casting machines and materials along with a knowledge base of die design. This system has been tested on a number of die-casting parts and results have been found to be along the lines of those obtained by the industry. The proposed system is more comprehensive than those presently available and is a step in the right direction for design-manufacturing integration for die-casting.     

An engineering method for complex structural optimization involving both size and topology design variables

This work presents an engineering method for optimizing structures made of bars, beams, plates, or a combination of those components. Corresponding problems involve both continuous (size) and discrete (topology) variables. Using a branched multipoint approximate function, which involves such mixed variables, a series of sequential approximate problems are constructed to make the primal problem explicit. To solve the approximate problems, genetic algorithm (GA) is utilized to optimize discrete variables, and when calculating individual fitness values in GA, a second-level approximate problem only involving retained continuous variables is built to optimize continuous variables. The solution to the second-level approximate problem can be easily obtained with dual methods. Structural analyses are only needed before improving the branched approximate functions in the iteration cycles. The method aims at optimal design of discrete structures consisting of bars, beams, plates, or other components. Numerical examples are given to illustrate its effectiveness, including frame topology optimization, layout optimization of stiffeners modeled with beams or shells, concurrent layout optimization of beam and shell components, and an application in a microsatellite structure. Optimization results show that the number of structural analyses is dramatically decreased when compared with pure GA while even comparable to pure sizing optimization.