基于DPC-CZM混合模型的金属粉末压坯裂纹三维数值模拟

Three-dimensional Numerical Simulation of Green Metal Powder Compacts Crack Based on DPC-CZM Mixed Model

消除和控制金属粉末压坯裂纹对生产高质量粉末冶金零件具有指导作用。本工作将修正的Drucker-Prager Cap(DPC)模型与内聚力模型(CZM)相结合,分别定义金属粉末压坯实体单元与零厚度内聚力单元的力学行为。通过巴西圆盘和单轴压缩试验获取压坯断裂性能参数,编写Python程序在实体单元中批量插入零厚度内聚力单元,模拟金属粉末压坯在外载荷作用下的拉伸和剪切裂纹以及裂纹扩展过程,并与实验结果进行对比分析。研究结果表明,采用指数型内聚力本构模型与DPC模型混合,可更准确地描述压坯裂纹损伤区的变化,与零厚度内聚力单元相关的裂纹扩展过程与实验结果更为一致。

Elimination and control of green metal powder compacts cracks can guide the production of high-quality powder metallurgy parts.In this work,the modified Drucker-Prager Cap(DPC)model and the cohesive model(CZM)are combined to define the mechanical behavior.The modified DPC model is used to define the solid elements,the cohesive model is used to define the zero-thickness element.Through Brazilian disc and uniaxial compression test,the fracture performance parameters of the blank were obtained,then the Python program was programmed to insert zero-thickness cohesive element in the solid element.The tensile and shear crack of green metal powder compacts under external load are simulated and compared with the experimental results.The results show that combining the exponential cohesive zone constitutive model with the DPC model can be used to describe the change of crack damage zone more accurately,which was also able to reflect the green compacts damage process and crack propagation associated with the zero-thickness elements.