融合点阵拓扑优化法和熵权法的铲运机外观设计

为更好地指导矿山开采大型机械设备的创新设计,归纳铲运机外观特点,提出点阵拓扑优化法和熵权法(EWM)设计、评估铲运机外观。首先,通过点阵拓扑优化法设计铲运机外观,使用层次分析法-熵权法(AHP-EWM)对评价指标赋权,搭建层次准则模型;其次,通过调研归纳出创造性指标、美学指标、功能性指标、经济性指标、技术性指标5个指标并建立评价体系;然后,运用层次分析法(AHP)对一级指标主观赋权,通过EWM分析二级指标的客观权重,依据python计算灰色关联度、多属性决策分析权重(CRITIC)、独立性权重、模糊综合评价法和逼近理想解排序法、理想点法(TOPSIS法)5种方法的权重,通过对比分析并验证AHP-EWM的可行性;最后,基于指标权重与方案得分优化备选方案设计,并使用最小支持向量机(LSSVM)来验证模型。结果表明:使用LSSVM模型进行回归分析,其决定系数达到0.93以上,均方误差在0.01以内,明显优于传统模型且精度较高,验证点阵拓扑优化法和EWM相结合的优化决策模型。

基于人工材料密度的新型拓扑优化理论和算法研究

对基于人工材料密度的拓扑优化理论作了深入分析;推导出了一种基于人工材料密度的拓扑优化准则算法,将该算法应用于拓扑优化的计算中,并给出了基于人工材料密度的拓扑优化迭代分析流程;提出了一种卷积因子方法,用于消除拓扑优化计算结果中易出现的棋盘格式和多孔材料现象;通过数值计算验证了理论和算法的有效性;分析讨论了不同优化参数对拓扑优化计算结果的影响。

轮盘概念设计中拓扑和形状同时优化方法

为了减小人为选择参数对优化结果的影响,针对航空发动机轮盘概念设计阶段的结构优化问题,提出了拓扑和形状同时优化(STSO)法.该方法是在变密度(SIMP)法的基础上,通过分析优化目标和约束的灵敏度,用序列二次规划优化(SQP)法进行求解.接着,以板壳结构为例,对比分析了STSO法和分步优化法的结果,说明了拓扑和形状同时优化方法的优点.最后,将同时优化方法应用于轮盘结构概念设计,对比分析了使用拓扑和形状同时优化方法与单独拓扑优化方法进行轮盘结构优化的结果,探讨了不同振型对应的频率约束对优化结果的影响.结果表明,不同振型对应的频率约束下优化结果的结构形式呈现多样性;相较于单独拓扑优化方法,STSO法收敛速度较快、结果也更精确;但是由于形状优化变量取值范围选取不当,有可能会出现网格畸变过大,而导致STSO法所得的结果无效.

应用拓扑优化理论进行结构概念设计

介绍了将拓扑优化方法与CAD/CAE系统进行集成,应用于解决船舶舵叶连接法兰面加工专机的升降台的拓扑结构优化.优化结果为结构详细设计阶段提供了设计优化区域和原型.

基于变密度法的山地自行车关键连接结构件拓扑优化设计

针对山地自行车减震器端和车架连接端的关键结构部件的轻量化设计问题,构建等比例三维实体模型,并采用变密度理论的拓扑优化方法,以最大化刚度为优化目标,以设计空间总体积和质量作为约束条件,对山地自行车结构部件进行拓扑优化再设计。优化求解获得一个新型的连接结构件,并对该结构在实际工况下的Mises应力、最大位移和安全系数等进行仿真校核,通过优化前后结构的分析结果综合对比,发现在保证结构部件强度、可靠性的前提下,该结构部件实现减重约50%,极大节省材料消耗。

基于拓扑优化的拼焊板后背门轻量化设计

将拼焊板技术应用于汽车轻量化设计,提出了基于拓扑优化的拼焊板轻量化设计方法。通过SIMP(solid isotropic material with penalization)法拓扑优化确定分块数目以及焊缝线位置。再以板件厚度作为设计变量,利用序列二次规划法进行多目标优化。运用该方法对某SUV车型后背门进行了轻量化设计,在保证拼焊板后背门各种刚度和模态性能指标的前提下,达到了轻量化的效果。具有工程实际意义。

基于复杂约束拓扑优化的负泊松比超材料设计

针对现阶段超材料拓扑优化设计在飞行器设计领域存在的微观尺度上难以制造和宏观尺度上不具有周期性的问题,提出了一种宏观尺度下的超材料拓扑优化设计方法,分别应用优化准则法和移动渐近线法进行了指定泊松比约束的超材料拓扑优化设计,得到了在横向、纵向两个方向上的泊松比都满足约束的负泊松比超材料,并对两种优化算法的设计结果进行了对比分析.针对拓扑优化得到的胞元构型,建立了理论模型和有限元模型,对拓扑优化结果的力学性能进行验证.经理论模型和有限元模型计算,拓扑优化设计结果的泊松比满足设计要求,证明了宏观尺度拓扑优化方法设计负泊松比超材料的有效性.

基于拓扑与形状优化的超薄圆锯片曲线缝结构设计

为实现超薄型圆锯片曲线缝的结构设计,基于变密度法拓扑优化和模式搜索算法的形状优化相结合的方法,对圆锯片的曲线缝结构进行优化设计。通过基于变密度法的拓扑优化,确定曲线缝开设位置;以圆锯片整体振幅作为评价标准,以拓扑优化后得出的设计域作为边界条件,通过模式搜索算法对圆锯片曲线缝结构形状进行优化,得出给定约束和载荷条件下的最优解。在试验过程中进一步证明了曲线缝形状对锯片轴向振动影响的重要性。

含有限PMU的主动配电网故障定位

对于含分布式电源(DG)的主动配电网,基于同步相量测量单元(PMU)的监测信息进行故障分析与处理,从而达到定位目的。首先采用拓扑优化法对PMU进行布点优化配置,同时将系统划分为不同区域。利用PMU监测所得实时潮流和电气量信息,基于功率增量方向原理可初步判断发生故障的区域;其次计算候选故障区域内各条区段发生不同类型故障时,各节点PMU相电流计算值,并与实际短路时的电流测量值相比较,利用区段定位优化模型所得计算误差选出故障区段;最后对于故障区段,利用基于双端相量信息的测距公式得到具体故障位置。仿真基于改进IEEE 33节点配电系统进行了不同位置、不同类型以及不同电源出力控制的短路实验,结果显示在不同短路条件下的系统定位误差均低于1%。

Multiobjective Optimization of Truss Topology by Linear/Sequential Linear Programming Method

The present paper deals with a multiobjective optimization of truss topology by either Sequential Linear Programming （SLP） method or Linear Programming （LP） method. The ground structure approach is often used to solve this kind of design problems. In this paper, the topology optimization is formulated as a Multiobjective Optimization Problem （MOP）, which is to find the cross-sectional area of truss members, such that both the total volume of members and the weighted mean compliance are minimized. Based upon the Karush-Kuhn-Tucker conditions （the optimality condition）, the Pareto optimal front of this problem can be obtained theoretically. The truss topology optimization under multiple load cases can be solved by the SLP. On the other hand, the LP such as the Simplex method or the interior point method can be applied to find one of the Pareto optimal solutions of the MOP under single load case. The applications of either the SLP or the LP are illustrated in numerical examples with discussion on characteristics of design results.

A new solution for topology optimization problems with multiple loads:The guide-weight method

The guide-weight method is introduced to solve two kinds of topology optimization problems with multiple loads in this paper.The guide-weight method and its Lagrange multipliers' solution methods are presented first,and the Lagrange multipliers' soution method of problems with multiple constraints is improved by the dual method.Then the iterative formulas of the guide-weight method for topology optimization problems of minimum compliance and minimum weight are derived and coresponding numerical examples are calculated.The results of the examples exhibits that when the guide-weight method is used to solve topology optimization problems with multiple loads,it works very well with simple iterative formulas,and has fast convergence and good solution.After comparison with the results calculated by the SCP method in Ansys,one can conclude that the guide-weight method is an effective method and it provides a new way for solving topology optimization problems.

Compliant mechanisms design based on pairs of curves

The success of compliant mechanism design by structural topology optimization approach depends,to a large extent,on its structural geometry representation scheme.In this work,a novel representation scheme based on pairs of curves is presented.In the representation,the structure is characterized by a set of input/output(I/O) regions.While it is still unknown how the rest of the design space will be occupied by the structure,the I/O regions must exist somewhere because any structure must have parts which interact with its surroundings by way of at least one loading region,one support region,and one output region.For a valid structural design,pairs of Bezier curves are used to connect I/O regions in order to form one single connected load-bearing structure.The boundary is explicitly described,so the need for smoothening of the blurred and jagged edges can be avoided by developing such a representation scheme to directly generate smooth boundary structures.With the scheme,shape and topology can be optimized simultaneously,and the obtained topology solutions have no check-board phenomena nor intermediate zones.A multi-objective genetic algorithm is then applied to couple with the representation scheme for defining and encoding the structural geometry in the form of graph.The solution framework is integrated with a nonlinear fixed grid finite element method(FG-FEM) code for large-displacement analyses of the compliant structures.Simulation results from a displacement inverter indicated that the proposed representation scheme is appropriate.

Topology optimization of thermoelastic structures using the guide-weight method

The guide-weight method is introduced to solve the topology optimization problems of thermoelastic structures in this paper.First,the solid isotropic microstructure with penalization(SIMP)with different penalty factors is selected as a material interpolation model for the thermal and mechanical fields.The general criteria of the guide-weight method is then presented.Two types of iteration formulas of the guide-weight method are applied to the topology optimization of thermoelastic structures,one of which is to minimize the mean compliance of the structure with material constraint,whereas the other one is to minimize the total weight with displacement constraint.For each type of problem,sensitivity analysis is conducted based on SIMP model.Finally,four classical 2-dimensional numerical examples and a 3-dimensional numerical example considering the thermal field are selected to perform calculation.The factors that affect the optimal topology are discussed,and the performance of the guide-weight method is tested.The results show that the guide-weight method has the advantages of simple iterative formula,fast convergence and relatively clear topology result.

A novel global optimization method of truss topology

This paper proposes a global topology optimization algorithm based on subset simulation for the singular optimum problem subject to stress constraints of trusses. The constraints are handled by a fitness function which reflects their degree of violation. The rational and global topology results are guaranteed by the judgment of the samples’ rationality and the Metropolis-Hasting algorithm. Three examples show that the established method can quickly reduce the searching region to the feasible region and converge to the global optimum precisely enough for the singular optimum problem.

Algorithms for seismic topology optimization of water distribution network

As an essential lifeline engineering system,water distribution network should provide enough water to maintain people's life after earthquake in addition to working under daily operation.However,the design of water distribution network usually ignores the influence of earthquake,resulting in water stoppage in large area during many recent strong earthquakes.This study introduced a seismic design approach of water distribution network,i.e.,topology optimization design.With network topology as the optimization goal and seismic reliability as the constraint,a topology optimization model for designing water distribution network under earthquake is established.Meanwhile,two element investment importance indexes,a pipeline investment importance index and a diameter investment importance index,are introduced to evaluate the importance of pipelines in water distribution network.Then,four combinational optimization algorithms,a genetic algorithm,a simulated annealing genetic algorithm,an ant colony algorithm and a particle swarm algorithm,are introduced to solve this optimization model.Moreover,these optimization algorithms are used to optimize a network with 19 nodes and 27 pipelines.The optimization results of these algorithms are compared with each other.

Deployment dynamics and topology optimization of a spinning inflatable structure

Inflatable space structures may undergo the vibration of a long duration because of their features of dynamic deployment,high flexibility,and low-frequency modes.In this paper,a topology optimization methodology is proposed to reduce the vibration of a spinning inflatable structure.As the first step,a variable-length shell element is developed in the framework of arbitrary Lagrange-Euler(ALE)and absolute nodal coordinate formulation(ANCF)to accurately model the deployment dynamics of the inflatable structure.With the help of two additional material coordinates,the shell element of ALE-ANCF has the ability to describe the large deformation,large overall motion,and variable length of an inflatable structure.The nonlinear elastic forces and additional inertial forces induced by the variable length are analytically derived.In the second step,a topology optimization procedure is presented for the dynamic response of an inflatable structure through the integration of the equivalent static loads(ESL)method and the density method.The ESL sets of the variable-length inflatable structure are defined to simplify the dynamic topology optimization into a static one,while the density-based topology optimization method is used to describe the topology of the inflatable structure made of two materials and solve the static optimization problem.In order to obtain more robust optimization results,sensitivity analysis,density filter,and projection techniques are also utilized.Afterwards,a benchmark example is presented to validate the ALE-ANCF modeling scheme.The deployment dynamics and corresponding topology optimization of a spinning inflatable structure are studied to show the effectiveness of the proposed topology optimization methodology.