一个机翼肋板的FreeSize和Topology优化结果比较

一个机翼肋板的FreeSize和Topology优化结果比较
前言
应用OptiStruct软件中分别采用FreeSize和Topology优化方法对一个机翼肋板结构进行了优化设计。

结构部件描述——四个板壳结构部件：总体尺寸24（12）*30，厚度0.1、0.2、0.06；
载荷和边界条件：
结构优化设计：The design region is the web and the rest of the components are non-design.
设计目标:：Minimize weighted compliance WCOMP；加权柔性最小；
约束条件：V olume fraction on the web < 0.3；web的体积比例小于30%；
free sizing optimization的设计变量：Thickness of each shell element in the design space；设计空间中每个单元的厚度；
拓扑优化（topology optimization）的设计变量：Element density of each element in the design domain；设计域中每个单元的密度；
FreeSize优化
图1 free-sizing优化结果（初始均匀厚度0.1，下图表示厚度大于0.024的材料）Topology优化
图2 Topology优化结果（初始均匀厚度0.1，下图表示厚度大于0.024的材料）优化结果比较、分析、结论
Results from the topology optimization show a truss type design with extensive cavities and voids, while the results from free-sizing optimization tend to come up with shear panels. While solid/void density distribution is the only choice for solid elements; for shell structures, intermediate densities can be interpreted as different thicknesses and penalizing then could result in potentially inefficient shell structures. Moreover, since a large portion of aerospace structures are shell structures, a shear panel type design is often desirable for manufacturing purposes especially for machine milled shell structures. Free-sizing optimization can prove to be very beneficial in those situations.。