针对3D打印材料孔洞应力集中计算的映射算法

目的 利用映射算法以较小计算成本获得3D打印材料孔洞应力集中分布情况，为3D打印材料疲劳寿命预测及结构优化设计的有限元分析提供新方法。方法 提取单个孔洞应力集中影响范围内的节点及应力，并计算出各节点的应力集中系数。以寻找最近点的方式将无孔洞模型相应节点的应力值乘以不同的应力集中系数来体现孔洞的应力集中。若多节点映射到同一节点，则乘以多个应力集中系数的平均值；对距离边界较近的点，则乘以边界影响系数。结果 材料内部孔洞的映射结果与实际计算结果误差小于8%；而对于自由边界孔洞聚集的情况，误差小于15%。结论 映射算法能够有效表征3D打印材料孔洞的应力集中，以较小的成本获得含孔洞缺陷模型的应力分布。该算法为临床植入体优化设计及疲劳分析提供有限元结果。
Objective To obtain the distribution of stress concentration on the microporous structure of 3D-printed materials through a mapping algorithm with low calculation cost, so as to provide a new method of finite element calculation of 3D-printed materials for the prediction of fatigue life and the optimization of structural design. Methods Node coordinates and stress values within the influential region of the single pore were extracted to calculate the stress concentration coefficients of different nodes. The nearest node to each node on the ideal model was determined by distance, and the corresponding coefficient was multiplied by its stress value. When the nearest nodes of several nodes were the same, the average of these coefficients was assigned. For the pores close to the edge, an edge coefficient must be multiplied to reduce the error. Results An error of less than 8% between the mapping result and the calculation result was achieved for the case in which the pores were not near the edge, but for the case in which the pores were close to each other near the edge, the error was less than 15%. Conclusions The mapping algorithm can effectively characterize the stress concentration of the microporous structure of 3D-printed materials, and determine the stress distribution with low cost. This novel algorithm provides the finite element result for the optimization design and fatigue analysis of implants in clinical applications.