粉末高速压制成形过程中的应力波分析

The pressure wave analysis in high velocity compaction process

应用离散单元法,模拟了粉末高速压制成形过程中的压力传播过程.根据粉末高速压制成形的工艺特性,把一次压制过程分为弹性加载、塑性变形、弹性卸载三个阶段;基于离散单元法的基本理论,分别建立了三个阶段的控制方程;应用PFC2D软件对粉末高速压制过程模腔内部颗粒的运动状态进行了数值模拟,给出了压坯内部的压力分布,得出了实验中无法测量的压坯内部应力传播波形.数值模拟结果显示,压力作用曲线表现出明显的弛豫现象,形成了倾斜度不同的锯齿状加载波形和卸载波形,压坯底层的应力波与实验得到的应力波相符.

The pressure propagation in high velocity compaction process is simulated based on the discrete element method in this paper.Because the full process is divided into elastic loading,plastic deformation and elastic unloading,the governing equations are established in three stages respectively.With the help of computing software PFC2D,the impacting force through different layers of powders can be obtained,which cannot be observed in experiment.The simulation results show obviously a delay phenomenon and serrate waves with different gradients in loading and unloading processes.Finally,the simulated low-level stress waves are compared with available experimental data,which are consistent with each other.