提高组件系统布局协同优化设计效率的新策略

组件系统布局协同优化设计是一种能够同时进行组件装填和结构构型的优化设计方法.提出提高协同优化设计效率的新方法引入以下3种新技术:①采用改进的网格嵌入技术,简化了组件的网格嵌入过程,提高了有限元建模效率;②引入超单元技术,将有限元模型的组件部分生成为组件超单元,节省了有限元计算分析时间;③采用面向超单元的几何设计变量半解...     

基于图论和拓扑结构分析的机械式无级变速器的创新设计

归纳了原始机构的拓扑构造特性,运用图论理论得到了原始机构的拓扑缩图.通过对机构的原始拓朴缩图进行二度点的分配,消去同构方案后,即可综合出符合条件的拓扑全图和一系列相时应的运动链图谱.在此基础上指定各构件和运动副的类型,得到与原始机构具有相同或相似功能的新型机构.设计者可根据功能要求和具体的设计环境,从中筛选出好的结构.     

基于类桁架连续体框架结构位移约束的拓扑优化

采用正交纤维增强材料模型,在弱的基材料内沿正交方向嵌入致密的杆件,以节点的密度和方向作为设计变量.在水平荷载作用下,以节点在任意一点水平方向的位移为目标函数,采用有限元分析方法优化框架结构材料的分布形成类桁架连续体.最后将结果应用于工程实例,并采用ANSYS进行对比分析.     

考虑可制造性的拓扑优化结果的几何重构

拓扑优化结果是一个边界呈离散阶梯状的非参数化模型,这使得拓扑优化结果的制造变得困难,因此需要将拓扑优化结果参数化几何重构,获得光滑的边界以满足机械制造要求,并且尽量不影响拓扑优化结果的结构响应。针对该问题,首先对拓扑优化结果进行二值化处理和边界识别,然后利用链码对拓扑优化结果的离散边界点进行排序和分段,最后用B样条曲线分段描述拓扑优化结果的外边界与内边界完成参数化建模。通过算例验证了几何重构方法的可行性,算例表明在满足可制造性要求的前提下,重构模型的结构响应能够较好的与拓扑优化初始设计结果保持一致,结构响应误差可以控制在5%以内。     

基于HyperWorks的卡车车身结构拓扑优化设计

以数学规划为基础,使材料在设计空间中得到最优的分布和形状,为设计者提供设计思路,能够缩短新产品的设计时间。利用变密度法,对卡车车架进行拓扑优化设计,不但满足了设计要求,而且为此类超静定结构的设计提供了思路。     

全承载式客车车身结构轻量化设计

以某全承载式客车车身结构为基础车型,构建拓扑优化模型,把车身侧围及顶盖部分区域作为设计空间;以质量分数为约束条件,加权柔度最小为目标;选取最为常见的四种极限工况,通过Hyperwork软件中的OptiStruct进行计算,经过若干论迭代后得到拓扑优化的结果。根据拓扑优化结果,结合工程要求及规范和客车车身应具备的整体性能,指导客车车身设计,在保证车身结构性能要求的前提下,合理布置材料,提高材料的利用率,减少冗余,达到车身结构轻量化的目的。     

桁架结构选型优化设计的新探索

考虑桁架结构选型的复杂性 ,提出一种基于拓扑组概念的实际方法 :先决定可能的拓扑组数目 ,经过结构静定性分析、节点检查和刚体运动检查以减少重分析次数 ,最终进行横截面积优化得到最佳结构型式。结论表明该方法实用、简单和可靠     

几种交流稳压电源主电路拓扑

对现有的交流斩控电路进行了分析,给出了工作模式和输入输出关系,并简要介绍了其优点.     

METAMORPHIC MECHANISMS AND THEIR CONFIGURATION MODELS

0 INTRODUCTION Mechanisms are fundamental PartS Of machines and robots, and ~ the central pieces for aPPliedInathematics. Mathematical tools like topological graph['], algebra['l, geometry['], and screw theoryL',']have been used to analyze and synthesize mechanisms. The study revealed new mechanisms and.onsbeti..,[6'7], and alternatively Presented new aPPlications['J for traditional mechanisms.New deployable mechanism was found in the study 'of truss,tru.tume[9] and used as a highlyco…     

Optimisation of structured grid spacing parameters for separated flow simulation using mathematical optimisation

This paper describes the use of computational fluid dynamics (CFD) and mathematical optimisation techniques to minimise the error in predicting the recirculation zone for a separated flow topology. Grid spacing parameters are varied in the optimisation process. The accuracy of separated flow solutions is known to be dependent on the grid resolution and clustering. Although general guidelines have been developed for grid generation of separated flow topologies, the flow solutions using the resulting grids often under-predict features like recirculation zones. This study addresses this aspect by providing an automatic tool for optimising the grid for solution accuracy. This approach has until recently been too expensive, but is becoming more viable with ever-increasing computer power. A two-dimensional sinusoidal hill is used as an example of a separated flow topology. The CFD simulation employs the commercial CFD solver STAR-CD to solve the Reynolds-Averaged Navier–Stokes equations with the RNG k– turbulence model. CFD solution time is drastically reduced by making use of initial field restarts. The optimisation is carried out by means of Snyman's DYNAMIC-Q method, which is specifically designed to handle constrained problems where the objective or constraint functions are expensive to evaluate. Six design variables (grid spacing parameters) are considered in this study. The results indicate that the re-attachment point of the recirculation zone is predicted to within 1% of the specified experimental value in four optimisation iterations and therefore represents a cost-effective way to determine grids based on solution accuracy.