复杂形状粉末冶金压坯裂纹损伤模型及防控方法研究

Powder Metallurgy(PM) has become preferred manufacturing technology on key components in the aeroengine and automotive manufacturin. But cracking is one of the critical concerns in the PM industry, especially with the increasing demand for comples shaped and high- performace parts. Currently, predict on crack in powder compacts are mostly concentrated in the qualitative analysis, as well as the lack of consideration in interaction and contact between the all phases during the forming process. And then, the project intends to establish a more accurate powder forming mechanical model based on the generalized plastic mechanics as well as metal powder compacts model crack damage model and damage evolution criterion. The quantitative analysis and prevention of cracks on complex green powder metallurgy compacts in all phases will performance by extend the finite element method (X-FEM). The cracks prevention methods in complex green powder compacts will proposed based on the crack formation law and limit working parameters. This research will provide scientific reference on designs of PM components, compaction process and die.

粉末冶金技术已成为航空发动机和汽车关键零部件的优选制备技术。但生产高精度、形状复杂的零件压坯时，其裂纹的产生是粉末冶金工业一直需要解决的问题。目前粉末压坯的裂纹预测研究大多集中在定性分析，且缺乏考虑成形过程中各环节之间的相互影响和联系。为此，本项目拟基于广义塑性力学建立更精确的粉末成形力学模型与金属粉末压坯裂纹损伤模型，以及压坯裂纹损伤演化准则；以扩展有限元（X-FEM）分析方法为手段，实现复杂形状压坯全制备周期内裂纹损伤定量分析与预测，获得压坯裂纹损伤规律与极限工况参数；基于以上成果，提出压坯裂纹损伤防控方法，为粉末冶金零件设计、压制工艺设计和模具设计提供科学的参考依据。

本项目基于广义塑性力学模型建立金属粉末压坯裂纹损伤模型，并对复杂形状粉末冶金零件压坯裂纹损伤及防控方法进行研究。主要研究内容有：基于实验参数建立密度相关的金属粉末成形数学模型，并结合反演优化方法与Python语言编写程序，实现模型参数快速获取；针对金属粉末压坯在成形过程中裂纹形成的特点，建立金属粉末压坯裂纹损伤模型，推导软化准则，并结合断裂破坏实验确定模型参数，利用Abaqus子程序编写裂纹初始准则判据；分别采用内聚力单元和扩展有限元法对金属粉末压坯的拉伸裂纹以及剪切裂纹的形成与演化进行模拟验证分析；针对粉末冶金工业中四类典型零件进行压制成形过程的数值仿真，讨论不同压制工艺对压坯成形密度、裂纹损伤的影响，进而计算出极限工况参数，提出压坯裂纹损伤防控方法。本项目研究的重要结果为，基于Abaqus-Matlab联合仿真平台，采用Python语言开发GUI界面实现快速建模，结合Abaqus子程序开发，建立一套快速实现金属粉末压制成形模拟的一体化方法，包括材料模型参数的快速获取、压坯零件模型的参数化建模以及压坯裂纹的萌生和扩展，为粉末冶金零件设计、压制工艺设计和模具设计提供科学的参考依据，对生产高质量粉末冶金零件起到重要指导作用。