基于NSGA-II和SVDD的转向架构架异常状态监测

转向架构架状态监测是保证轨道车辆安全运营的重要途径.研究提出了一种基于NSGA-II和SVDD的转向架构架异常状态监测方法,针对构架异常状态下样本集的随机多样和不确定性,引入SVDD算法,以构架正常状态的样本集构建SVDD超球体模型对多工况条件下构架的异常状态进行识别.同时以SVDD超球体半径定义优化目标函数f1(传感器数量)和f2(超球体聚类指标),并基于NSGA-II算法对传感器分布进行了优化.在此基础上,搭建转向架构架状态监测实验平台,对多工况条件下构架的异常状态识别进行研究.结果表明:①经优化后的传感器分布方案能有效获取转向架构架状态监测数据,当优化方案中传感器数量达到3时,识别率达到91.33％;②以转向架构架正常状态样本集构建的SVDD模型对异常状态具有很好的识别效果.     

高速列车转向架的主动稳定性研究

提出了基于构架横向振动的高速列车稳定性主动控制方法,讨论了采用惯性作动器控制构架横向振动,以及对动力转向架驱动系统采用主动弹性悬挂这两种实施方式.以车辆蛇行稳定性指标和控制力作为两个目标函数,利用遗传算法(NSGA-II)来优化控制参数和驱动系统悬挂参数.研究表明构架横向振动控制可以有效地提高转向架蛇行稳定性.同时发现当直接反馈构架状态实现构架振动控制时,控制系统时滞易导致系统失稳,因此提出一种通过反馈附加振子状态的方法来减小时滞的影响,合理的附加振子悬挂参数有利于提高车辆系统稳定性.较硬的附加振子可提高转向架控制系统的蛇行临界速度裕度,但会导致控制系统在一定的时滞内出现不稳定的现象.因此,在优化附加振子悬挂参数时,必须同时兼顾转向架蛇行稳定性和控制系统稳定性.本文对于涉及的350 km/h高速列车转向架,得出了附加振子的最佳固有频率和阻尼比.     

轨道扣件检测系统设计与分析

为了满足轨道扣件动态检测的需求,设计了一种轨道扣件检测系统,包括照明系统、摄像系统等并通过悬挂系统安装在转向架构架前端。通过关键设备参数的选型计算,设计了安装结构然后校核悬挂系统的螺栓强度,验证其螺栓连接的可靠性。并对整体结构采用ANSYS Workbench有限元分析以及实验室验证,系统符合要求,满足线路的检测需要。     

面向火箭滑车底盘设计的变密度多载荷拓扑优化方法

针对火箭滑车底盘设计中的应用,提出一种变密度多载荷拓扑优化方法.在分析火箭滑车底盘优化设计要点的基础上,采用变密度多载荷拓扑优化方法,基于ANSYS系统实现了火箭滑车底盘的拓扑优化建模和求解,并对滑车底盘拓扑优化结果进行处理及分析,获得火箭滑车底盘的结构优化布局.实例结果表明,该方法能够提高产品设计质量与效率,可以为火箭滑车设计人员提供参考.     

基于有限元分析的地铁车辆转向架构架优化设计

为实现地铁车辆转向架的轻量化设计,参照国际标准UIC 615-4,计算某地铁车辆转向架构架的主要载荷.将垂向载荷、横向载荷和纵向载荷等6种载荷组合成5种超常载荷工况,经有限元强度分析,找出应力薄弱点.通过优化模型的建立和OptiStruct的优化,实现转向架构架的轻量化设计,总质量减轻约12%.     

基于ANSYS二次开发的结构拓扑优化

将先进的结构拓扑优化思想与成熟的有限元分析软件ANSYS相结合,基于ANSYS二次开发语言APDL和UIDL编制了结构拓扑优化程序,解决了ANSYS自带的拓扑优化模块中单元类型受限及不能应用于桁架结构优化的问题,充分利用ANSYS丰富的单元类型、强大的计算和后处理能力,有利于促进结构拓扑优化的应用和研究,拓宽ANSYS软件在结构拓扑优化方面的应用领域。     

SAR信号处理系统优化设计的研究和实践

SAR信号处理系统在实现超高图像分辨率要求的同时,还需要满足空间小型化的要求.为SAR信号处理系统的研制提供一些优化设计方法,包括核心芯片选择、拓扑结构优化设计、系统结构小型化设计和软件构架设计方法等.这些优化方法已在实际工程中得到应用.     

电动滑板桥轻量化优化设计

本文通过SolidWorks建立参数化的电动滑板桥三维模型,导入ANSYS Workbench中进行静力学分析,根据分析的应力、应变结果,进行拓扑优化,得到合理的拓扑结构。结合拓扑优化结果和工程经验,以质量最小为目标函数,强度为约束条件,进行滑板桥尺寸优化设计,在保证滑板桥强度前提下,优化后的滑板桥比原滑板桥质量减少了33.33%,取得良好的轻量化效果。该优化方法为电动滑板车轻量化设计提供一种思路。     

转向架齿轮箱吊杆的优化设计

针对某转向架齿轮箱吊杆开发设计过程中吊杆原始结构工作安全因数过大的问题,为进行轻量化设计,基于OptiStruct采用拓扑优化结合自由形状优化的方法对吊杆进行优化设计.优化后吊杆的质量减轻约38.3%,其工作安全因数和刚度满足要求.     

基于ANSYS Workbench的T形结构优化设计

针对T形结构传统设计周期长、材料利用率低、设计成本高等问题,使用SolidWorks建立数字模型,将其转换成ANSYS Workbench可读的格式文件,进行拓扑优化设计。对T形结构在载荷作用下进行最优化设计,建立以单元材料密度为设计变量,以结构最小柔顺度为目标函数,以质量减少百分比为约束函数的数学模型。采用ANSYS Workbench的Topology Optimization模块进行拓扑优化设计,对比优化前、后结构的应力和变形,可知运用拓扑优化技术实现T形结构的轻量化设计合理有效。     

On the influence of model reduction techniques in topology optimization of flexible multibody systems using the floating frame of reference approach

Employing the floating frame of reference formulation in the topology optimization of dynamically loaded components of flexible multibody systems seems to be a natural choice. In this formulation the deformation of flexible bodies is approximated by global shape functions, which are commonly obtained from finite element models using model reduction techniques. For topology optimization these finite element models can be parameterized using the solid isotropic material with penalization (SIMP) approach. However, little is known about the interplay of model reduction and SIMP parameterization. Also securing the model reduction quality despite major changes of the design during the optimization has not been addressed yet. Thus, using the examples of a flexible frame and a slider-crank mechanism this work discusses the proper choice of the model reduction technique in the topology optimization of flexible multibody systems.     

基于无网格径向点插值方法的简谐激励下的连续体结构拓扑优化

针对用有限元法进行连续体结构拓扑优化时需不断重构网格来处理网格畸变和网格移动,且存在数值计算不稳定等问题,基于无网格径向点插值方法(Radial Point Interpolation Method,RPIM)对简谐激励下的连续体结构进行拓扑优化.选取节点的相对密度作为设计变量,以结构动柔度最小化为目标函数,基于带惩罚的各向同性固体微结构(Solid Isotropic Microstructure with Penalization,SIMP)模型建立简谐激励下的优化模型;采用伴随法求解得到目标函数的敏度分析公式;利用优化准则法求解优化模型.经典的二维连续体结构拓扑优化算例证明该方法的可行性和有效性.     

Evolutionary topology optimization of continuum structures with smooth boundary representation

This paper develops an extended bi-directional evolutionary structural optimization (BESO) method for topology optimization of continuum structures with smoothed boundary representation. In contrast to conventional zigzag BESO designs and removal/addition of elements, the newly proposed evolutionary topology optimization (ETO) method, determines implicitly the smooth structural topology by a level-set function (LSF) constructed by nodal sensitivity numbers. The projection relationship between the design model and the finite element analysis (FEA) model is established. The analysis of the design model is replaced by the FEA model with various elemental volume fractions, which are determined by the auxiliary LSF. The introduction of sensitivity LSF results in intermediate volume elements along the solid-void interface of the FEA model, thus contributing to the better convergence of the optimized topology for the design model. The effectiveness and robustness of the proposed method are verified by a series of 2D and 3D topology optimization design problems including compliance minimization and natural frequency maximization. It has been shown that the developed ETO method is capable of generating a clear and smooth boundary representation; meanwhile the resultant designs are less dependent on the initial guess design and the finite element mesh resolution.     

Automotive applications of topology optimization

Topology optimization is used for obtaining the best layout of vehicle structural components to achieve predetermined performance goals. An in-house topology optimization software, TOP, has been developed to analyse important automotive components. The topology design problem is formulated as a general optimization problem and is solved by the mathematical programming method. The MSC/NASTRAN finite element code is employed for response analyses. The use of MSC/NASTRAN is significant, because it not only allows engineers to use a wellaccepted and widely-used finite element code with no size limit on the model, but also permits developers to concentrate on the rest of the topology optimization program. Three automotive examples including a simplified truck frame, a deck lid, and a space frame structure are presented.     

Topology optimization of free vibrating continuum structures based on the element free Galerkin method

In this paper, the topology optimization design of the free vibrating continuum structures is formulated based on the element free Galerkin (EFG) method. Considering the relative density of nodes as design variable, and the maximization of the fundamental eigenvalue as an objective function, the mathematical formulation of the topology optimization model is developed using the solid isotropic microstructures with penalization (SIMP) interpolation scheme. The topology optimization problem is solved by the optimality criteria method. Finally, the feasibility and efficiency of the proposed method are illustrated with several 2D examples that are widely used in the topology optimization design.     

An efficient moving morphable component (MMC)-based approach for multi-resolution topology optimization

In the present work, a highly efficient moving morphable component (MMC)-based approach for multi-resolution topology optimization is proposed. In this approach, high-resolution optimization results can be obtained with a smaller number of design variables and a relatively low degree of freedoms (DOFs). This is achieved by taking the advantage that the topology optimization model and the finite element analysis model are totally decoupled in the MMC-based problem formulation. A coarse mesh is used for structural response analysis and a design domain partitioning strategy is introduced to preserve the topological complexity of the optimized structures. Numerical examples are then provided so as to demonstrate that with the use of the proposed approach, computational efforts can be saved substantially for large-scale topology optimization problems.     

基于OptiStruct的麦弗逊悬架下控制臂优化

针对麦弗逊悬架下控制臂的优化问题,为减轻其质量、增强其刚度,基于拓扑优化理论和有限元法,用OptiStruct对某铸造麦弗逊悬架下控制臂进行拓扑优化.在规定的体积内获得最佳的材料分布,使刚度最大.优化后重建CAD模型,并与原件的刚度和模态进行比较,结果表明该优化能减轻控制臂质量、增强下控制臂刚度。     

基于拓扑和形貌优化的驾驶室结构设计

为实现汽车零部件的创新设计,以某工程车驾驶室的简化有限元模型为研究对象,用HyperMesh作前处理,在OptiStruct中建立多工况条件下拓扑优化与形貌优化组合的整体优化模型,通过OSSmooth工具将优化后的结果导出后在CATIA V5中显示.拓扑和形貌组合优化技术的实践表明,该方法对产品部件的综合设计具有较好的适用性,可为设计人员提供设计思路.