优化过程知识引导的挖掘机动臂结构优化设计新策略

针对现有智能优化算法求解挖掘机动臂结构优化问题效率低、易陷入局部最优等问题,提出一种优化过程知识挖掘、处理和利用策略.构建基于任务知识指导的优化过程知识挖掘、处理和利用机制,探讨了运用优化过程知识引导遗传算法数值优化搜索的途径,并建立群体成员分组的知识利用算子以及选择、交叉、变异操作的知识利用算子.以中型液压挖掘机动臂结构优化任务为例,以所构建的知识利用算子引导遗传算法的数值优化搜索,通过与现有遗传算法进行对比,表明优化过程知识的利用可以有效提高优化效率并改善优化效果.     

基于有限元分析的装载机铲斗结构优化

装载机铲斗的形状、结构复杂,传统的类比经验设计方法难以计算应力分布,结构设计不尽合理,存在很大的盲目性.采用Pro/E完成铲斗三维实体建模,然后将模型导入ANSYS中,进行铲斗的有限元分析,同时对各板件的厚度进行了结构优化.分析结果表明:铲斗在满足性能和强度要求的前提下实现了轻量化,对铲斗及其他复杂结构件的优化设计具有指导意义.     

铝制发动机盖行人保护分析与结构优化策略

基于行人碰撞保护标准在汽车设计中的要求,将铝材料应用于发动机盖,通过CAE仿真分析了铝制发动机盖和钢制发动机盖对行人碰撞头部伤害标准HIC。对铝制发动机盖的结构提出了优化策略,以达到碰撞时保护行人的目的。     

基于灵敏度变化率的渐进结构频率优化算法

为了提高渐进结构优化方法用于频率优化时计算效率和质量,首先提出了灵敏度变化率的概念.在此基础上,结合ESO方法和频率灵敏度,建立了结构有限单元增、删的准则,给出了一种新的频率优化算法.该算法采用了灵敏度再分配法,有效抑制了优化中的棋盘格,提高了优化效果.提供的算倒表明了该方法在频率优化时的效率和准确性方面有一定程度的提...     

大型卷板机上梁的模态分析与结构优化设计

在保证大型卷板机上梁结构力学特性的前提下,对上梁结构进行了简化,建立了有限元模型。通过对该有限元模型进行自由模态分析,得到上梁的各阶模态频率和振型,为动态设计提供了参考。对不合理结构进行优化设计,以提高上梁本身的固有频率,使上梁结构刚度更趋合理。总结提出提高结构模态频率和振型的措施。     

结合专家群体评估法的渐进结构优化算法

结构拓扑优化作为现在迅速发展的结构化设计的一个分支,已得到广泛应用。基于渐进结构优化(ESO)方法,结合灰色理论中的专家群体评估法,得到一种新的处理多目标优化的方法。首先使用线性加权法对一平面简支梁进行优化分析得到三组拓扑结构。然后运用该新方法对同一算例进行优化得到三组拓扑结构。并将最终拓扑结构进行对比。     

XFEM schemes for level set based structural optimization

In this paper, some elegant extended finite element method (XFEM) schemes for level set method structural optimization are proposed. Firstly, two- dimension (2D) and three-dimension (3D) XFEM schemes with partition integral method are developed and numerical examples are employed to evaluate their accuracy, which indicate that an accurate analysis result can be obtained on the structural boundary. Furthermore, the methods for improving the computational accuracy and efficiency of XFEM are studied, which include the XFEM integral scheme without quadrature sub-cells and higher order element XFEM scheme. Numerical examples show that the XFEM scheme without quadrature sub-cells can yield similar accuracy of structural analysis while prominently reducing the time cost and that higher order XFEM elements can improve the computational accuracy of structural analysis in the boundary elements, but the time cost is increasing. Therefore, the balance of time cost between FE system scale and the order of element needs to be discussed. Finally, the reliability and advantages of the proposed XFEM schemes are illustrated with several 2D and 3D mean compliance minimization examples that are widely used in the recent literature of structural topology optimization. All numerical results demonstrate that the proposed XFEM is a promising structural analysis approach for structural optimization with the level set method.     

废旧印刷电路板振动拆除装置设计及其动力学仿真

开发废旧印刷电路板上电子元件和基板的拆除分离设备,一直是电子电器产品回收的难点问题。在分析比较国内外现有废旧印刷电路板电子元件拆除方法的基础上,文章介绍了一种废旧印刷电路板元器件无损拆除装置的设计原理和结构模型。然后采用虚拟样机技术对废旧电路板元器件振动拆除过程中产生的接触—碰撞问题进行动力学仿真,确定了不同激振力下电路板与振动头之间的碰撞力(即拆除力)的大小的关系,从而优化设备结构参数、缩短设备开发周期、降低了开发成本。     

New knowledge-based genetic algorithm for excavator boom structural optimization

Due to the insufficiency of utilizing knowledge to guide the complex optimal searching, existing genetic algorithms fail to effectively solve excavator boom structural optimization problem. To improve the optimization efficiency and quality, a new knowledge-based real-coded genetic algorithm is proposed. A dual evolution mechanism combining knowledge evolution with genetic algorithm is established to extract, handle and utilize the shallow and deep implicit constraint knowledge to guide the optimal searching of genetic algorithm circularly. Based on this dual evolution mechanism, knowledge evolution and population evolution can be connected by knowledge influence operators to improve the conflgurability of knowledge and genetic operators. Then, the new knowledge-based selection operator, crossover operator and mutation operator are proposed to integrate the optimal process knowledge and domain culture to guide the excavator boom structural optimization. Eight kinds of testing algorithms, which include different genetic operators, arc taken as examples to solve the structural optimization of a medium-sized excavator boom. By comparing the results of optimization, it is shown that the algorithm including all the new knowledge-based genetic operators can more remarkably improve the evolutionary rate and searching ability than other testing algorithms, which demonstrates the effectiveness of knowledge for guiding optimal searching. The proposed knowledge-based genetic algorithm by combining multi-level knowledge evolution with numerical optimization provides a new effective method for solving the complex engineering optimization problem.     

3P3R型磨削机器人的结构参数计算与优化

针对设计机器人中考虑到灵活空间需要包络整个工件,灵活空间的大小受到机器人结构尺寸与磨削机和机器人的摆放位置影响等问题,提出了3P3R的结构构型,并对该机器人结构参数计算与灵活空间等方面进行研究。首先给出了运用旋量建模方法的运动学分析,后又将待加工的工件模型进行了简化,在总结前人工作的基础上,参考加工实际情况,提出了虚拟球的概念,针对特定的的加工工件设计机器人的尺寸,重点讨论了机器人与砂带机位置参数的计算方法,给出了详细公式推导与计算流程图,对于整个磨削系统的结构计算进行了系统综合,运用蒙特卡洛方法对于机器人的灵活空间进行了验证,并在Matlab平台上进行了编程实现。最后,研究结果证实,该优化算法具有可靠性与实用性;同时这种逆推机器人结构参数并优化的方法也可应用到其他机器人的结构设计中。     

人工神经网络在结构优化设计中的应用

将有限元法与人工神经网络相结合,利用人工神经网络的非线性映射能力,训练一个可以预测不同输入参数时的结构应力或位移等信息的人工神经网络,使其可以方便地代入到优化设计程序中,其中重点介绍的是人工神经网络的教师样本构造问题。用一实例详细说明了方法的使用过程,结果表明了这种方法的有效性。     

框式热压机机架有限元分析及结构优化设计

针对某型号框式热压机的框形板上横板与侧板拐角处发生断裂这一问题,利用Pro/E软件建立了热压机机架结构参数化模型,运用ANSYS软件时其机架进行有限元分析,找出了原结构设计存在的问题.在机架满足具有足够的强度和刚度的前提下,以机架结构的质量最轻为目标,对热压机的机架进行了结构参数优化设计.优化后的框架结构与原结构相比,使热压机质量减轻了约9%,最大应力降低了约23%,获得了较为理想的结构和尺寸,实现了增加热压机的使用寿命及降低制造成本的目的.     

基于均匀能密度准则的SKO法在结构优化中的应用

拓扑优化方法在结构设计的概念设计阶段是一种非常重要的方法,近年来一直是结构优化设计研究领域中的前沿课题和热点问题.研究结构优化仿生设计方法SKO法的原理及方法,以ANSYS为平台实现SKO法的软件操作,提出基于均匀能密度准则的SKO法,并对汽车发动机内罩进行拓扑优化,通过比较优化前后的数据证明,提出的方法正确、有效.     

电感位移传感器结构特性研究

在电感位移传感器设计中,电感传感器内线圈与磁芯的结构特性是影响传感器性能的关键因素。为提高传感器检测性能,根据毕奥-沙伐尔定律建立了传感器内线圈与磁芯模型,利用有限元分析软件建立了相应结构模型。通过分析线圈与磁芯各项参数变化以及线圈与磁芯存在安装与加工误差的情况,得到了各参数变化以及安装与加工误差对传感器测量性能的影响,以此对线圈和磁芯进行了优化。研究结果表明,当线圈长度与磁芯长度的比值在1.45~1.6之间时,传感器能获得较大的电感相对变化量;线圈长度、磁芯长度与磁芯半径的变化对线性度的影响不明显,线性度在0.5%附近,磁芯安装偏心与倾斜对传感器性能影响较小,可忽略不计;电感相对变化量会随着磁芯锥度的增大而减小。     

基于中心点精确响应面法的板壳结构优化

对响应面方法中两个最为关键的概念——近似函数及试验设计做了简单描述,选择线性函数作为约束条件的近似函数形式,并对位移和应力约束作不同处理,位移约束不合常数项,而应力约束含常数项。提出了一种适合建立一阶形式响应面并使结构分析次数最少的试验设计方法——中心扩展法。求解响应面时在最小二乘法的基础之上作了改进,提出中心点精确响应面法,使拟合的响应面中心点处的响应值精确等于有限元分析值。最后通过数值算例说明改进后的响应面法对于板壳结构优化的可行性和优越性。     

固定式刚度测试仪有限元分析及结构优化

固定式刚度测试仪是针对大型汽车覆盖件刚度测量的高精度测量仪器.通过确定相关参数、建立机架有限元模型,运用有限元软件ANSYS对固定式刚度测试仪初定方案进行了结构分析,并通过查看锡青铜衬套应力云图,找出初定方案所存在的问题;在此基础上对结构进行优化并进行有限元分析,通过对比分析结果,确定了固定式刚度测试仪优化后结构的合理性.优化方案解决了初定方案所存在的问题,减小了两边立导柱和衬套之间的摩擦力,改善了摩擦力的不均衡性,使横梁的升降更加平稳.     

多工况悬架下摆臂结构优化设计方法研究

采用了多种优化设计方法,以某悬架结构为例进行了结构优化设计方法研究.通过对车辆行驶工况和对车体空间布置的分析,建立了拓扑优化可设计域和非可设计域,完成了悬架结构的拓扑优化设计,并建立了工程结构.基于强度分布与应力干涉理论,将可靠性理论和优化方法相结合,进行了可靠性优化设计.其优化结果与尺寸优化和形状优化结果进行了对比,证明了优化设计方法的有效性和可行性,为工程结构提供了一种新设计思路.     

Spring-joint method for topology optimization of planar passive compliant mechanisms

There is seldom approach developed for the initial topology design of flexure-based compliant mechanisms. The most commonly-used approaches, which start with an existing rigid-body mechanism, do not consider the performances between different topologies. Moreover, they rely heavily on the rigid-body topology, therefore limit the diversity of compliant mechanisms topology. To obtain the optimal initial topology of such mechanisms directly from problem specifications without referencing to the existing mechanism topologies, a spring-joint method is presented for a restricted class of the serial passive flexure-based compliant mechanisms, which are the building blocks of parallel compliant mechanisms. The topology of the compliant mechanisms is represented by a serial spring-joint mechanism（SSJM） that is a traditional rigid-body mechanism with a torsional spring acting on each joint, and is described by position vectors of the spring-joints. A simplified compliance matrix, determined by the position vectors, is used to characterize the tip of the SSJM kinematically, and is optimized to ensure the desired freedoms of the compliant mechanisms during optimization. The topology optimization problem is formulated as finding out the optimal position of the spring-joints in a blank design domain with an objective function derived from the simplified compliance matrix. In design examples, syntheses of the compliant mechanisms with both single freedom and two decoupled freedoms are presented to illustrate the proposed method. The proposed method provides a new way for the initial design of flexure-based compliant mechanisms.     

面向结构形状控制的驱动器结构参数与控制电压协同优化设计

飞机翼面结构形状的控制设计是提高飞机性能的关键技术。本文以压电纤维复合薄膜（Microfiber Composite,MFC）为驱动器,研究了协同优化设计MFC驱动器结构参数与控制电压以使飞机翼面结构具有理想形状的方法。以MFC的电极宽度、电极指间距、MFC厚度、压电陶瓷体积分数等驱动器结构参数以及控制电压为设计变量,以控制偏差最小为优化目标,以驱动器的击穿电压为约束,建立了驱动器结构参数与控制电压协同优化设计的模型;通过分析MFC驱动器结构参数对驱动性能的影响,给出了最优的驱动器结构参数;针对类似机翼翼面形状的平板扭转型面,给出了驱动器结构参数与控制电压协同的最优控制设计。设计结果表明：对于扭转变形,多个不同控制电压控制的型面均方差是相同控制电压控制均方差的45%,分析结果验证了本文所建立的协同优化设计方法的有效性。     

Particle swarm optimization for achieving the minimum profile error in honing process

Gears are among the most important mechanical components of the modern industry. The topography of the gears’ tooth flank has an intricate and complex form and requires great finishing and quality. Commonly, traditional grinding processes are applied to finishing gear profile. However, the use of honing process has grown in recent years to provide the best finishing in industrial products. In this study, the honing process was improved applying a particle swarm optimization. Pinions of steering systems were used as work pieces to testify the optimization technique. The input parameters were the spindle speed, feed rate in X direction, feed rate in Z direction, oscillation time, and spark out time. The experimental measures were compared with simulation tests using the responses total profile deviation (f_α), total helix deviation (f_β), and total cumulative pitch deviation (f_p). The results showed that profile error was minimized, and the quality was improved based a set of strategies that were held simultaneously in the input parameters.