基于内聚力模型的金属粉末压坯拉伸裂纹扩展模拟

压坯裂纹损伤预测分析对于生产高质量粉末冶金零件具有重要的指导作用。本文将修正的Drucker–Prager Cap模型与内聚力损伤模型相结合,并利用Python语言在损伤断裂区域内批量插入内聚力单元,模拟金属粉末压坯在外载荷作用下裂纹扩展过程。同时,采用不同类型的内聚力模型对巴西圆盘实验过程进行模拟,通过实验验证对比分析可知,采用指数内聚力模型模拟压坯拉伸裂纹扩展的结果与实验结果更为吻合,并且与实验后期压坯边缘出现剪切带的现象也较为一致。

Simulation of tensile crack propagation of metal powder green compact based on cohesive zone model

The prediction and analysis of green compact crack damage have the important guiding effect on the production of high quality powder metallurgy parts.In this paper,the modified Drucker-Prager Cap model was combined with cohesive damage model,and the cohesive elements was inserted into fracture region by Python to simulate the crack propagation process of metal powder compact under the external load.At the same time,different types of cohesive zone models were used to simulate the Brazilian disk experiment.The experimental results show that the tensile crack propagation of green compacts simulated by exponential cohesive model is consistent with the experimental results,and the appearance of shear band at green compact edge in the later stage of experiment is similar with that simulated by exponential cohesive model.