Yang Wuxin, Huang Loulin, Singamneni Sarat
Department of Mechanical Engineering, Auckland University of Technology, Auckland, New Zealand.
3D Print Addit Manuf. 2023 Aug 1;10(4):792-807. doi: 10.1089/3dp.2021.0241. Epub 2023 Aug 9.
Spatially varying material properties allow the dynamic response of structural systems to be almost arbitrarily tailored, far beyond the first or fundamental natural frequency. Continuing advances in manufacturing technology are making it possible to achieve the necessary range of stiffness and density variations, but the design of these property distributions is a challenging task because of the complex multidimensional nature of the problem. Generative design methods based on evolutionary optimization algorithms have been successfully used to obtain solutions based on multi-material distributions. However, the applicability of these solutions is limited by their reliance on multi-material additive manufacturing (AM), which currently only offers digitally mixed acrylic polymer options that are generally unsuitable to produce functional parts. A novel structured material solution is proposed here, in which the problem domain is divided into several volume elements (voxels), each of which contains a structure whose geometrical form is altered to adjust its effective properties to desired values. The single material structural solution will be amenable for ready fabrication by the powder-based selective laser sintering and melting processes with real engineering polymer and metal systems, thereby allowing for the realization of the benefits in real-world applications. The resulting continuous design spaces are searched using a modern evolutionary algorithm, the covariance matrix adaptation evolution strategy (CMA-ES). A MATLAB implementation of this evolutionary design method, in conjunction with finite element simulations for fitness evaluation, showed good convergence for several different cantilever beam test cases when tested against several different sets of target natural frequencies. Correlations with the multi-material solutions show that the single structured material approach is on par or even better in some cases, even though the test domain was discretized into 80% fewer voxels than for the multi-material case. Furthermore, the voxel structures can be realized using current AM technologies.
空间变化的材料特性使结构系统的动态响应几乎可以任意定制，远远超出第一阶或基频。制造技术的不断进步使得实现必要的刚度和密度变化范围成为可能，但由于问题的复杂多维性质，这些特性分布的设计是一项具有挑战性的任务。基于进化优化算法的生成式设计方法已成功用于获得基于多材料分布的解决方案。然而，这些解决方案的适用性受到其对多材料增材制造（AM）的依赖的限制，目前多材料增材制造仅提供数字混合丙烯酸聚合物选项，通常不适合生产功能部件。本文提出了一种新颖的结构化材料解决方案，其中将问题域划分为几个体积元素（体素），每个体素都包含一种结构，其几何形状会被改变以将其有效特性调整到所需值。单一材料的结构解决方案将便于通过基于粉末的选择性激光烧结和熔化工艺，使用实际工程聚合物和金属系统进行现成制造，从而在实际应用中实现其优势。使用现代进化算法——协方差矩阵自适应进化策略（CMA-ES）搜索由此产生的连续设计空间。这种进化设计方法的MATLAB实现，结合用于适应度评估的有限元模拟，在针对几组不同的目标固有频率进行测试时，对几个不同的悬臂梁测试案例显示出良好的收敛性。与多材料解决方案的相关性表明，单一结构化材料方法在某些情况下相当甚至更好，尽管测试域离散化为体素的数量比多材料情况少80%。此外，体素结构可以使用当前的增材制造技术实现。
