On utilizing topology optimization to design support structure to prevent residual stress induced build failure in laser powder bed metal additive manufacturing
On utilizing topology optimization to design support structure to prevent residual stress induced build failure in laser powder bed metal additive manufacturing
复制标题
DOI：
10.1016/j.addma.2019.03.001
复制
发表时间：
2019-05-01
影响因子：
11
通讯作者：
To, Albert
中科院分区：
文献类型：
--
作者：
Cheng, Lin;Liang, Xuan;To, Albert
金属增材制造（AM）作为一种新兴的制造技术，已逐渐被接受用于制造最终用途部件。然而，阻碍其广泛应用的最关键问题之一是制造过程中残余应力积累导致的构建失败。本文的目的是研究利用拓扑优化设计支撑结构以减轻残余应力引起的建造失败的可行性。为了使拓扑优化计算上易于处理，固有应变法进行快速预测的残余应力在AM构建。利用周期性网格结构的开孔性和自支撑性，采用梯度网格结构优化设计支撑结构。优化的目标是在应力约束下使牺牲支撑结构的质量最小。通过限制屈服强度下的最大应力，可以防止由残余应力引起的破裂。为了验证该方法的可行性，分别设计了双悬臂梁和髋关节植入体的支撑结构。优化后的支撑结构可实现约60%的减重。优化后的支撑结构在AM实现设计后不再出现应力开裂，证明了该方法的有效性。
Metal additive manufacturing (AM) as an emerging manufacturing technique has been gradually accepted to manufacture end-use components. However, one of the most critical issues preventing its broad applications is on build failure resulting from residual stress accumulation in manufacturing process. The goal of this work is to investigate the feasibility of using topology optimization to design support structure to mitigate residual stress induced build failure. To make topology optimization computationally tractable, the inherent strain method is employed to perform fast prediction of residual stress in an AM build. Graded lattice structure optimization is utilized to design the support structure due to the open-celled and self-supporting nature of periodic lattice structure. The objective for the optimization is to minimize the mass of sacrificial support structure under stress constraint. By limiting the maximum stress under the yield strength, cracking resulting from residual stress can be prevented. To show the feasibility of the proposed method, the support structure of a double-cantilever beam and a hip implant is designed, respectively. The support structure after optimization can achieve a weight reduction of approximately 60%. The components with optimized support structures no longer suffer from stress-induced cracking after the designs are realized by AM, which proves the effectiveness of the proposed method.