应用于粉末冶金的修正Drucker-Prager/Cap模型

A MODIFIED DRUCKER-PRAGER/CAP MODEL FOR POWDER METALLURGY

摘要:

粉末冶金是金属材料成形工艺的重要环节,但现有各种模型都无法完整模拟金属粉末在压制前后期特有的力学性能。本文通过引入致密金属的屈服强度,对Drucker-Prager/Cap模型进行修改,将其屈服面限制在致密金属的Von Mises屈服面以内,并随着压制过程,使之无限接近Von Mises屈服面。通过与文献试验数据对比,证明了本文提出的修正模型具有相当高的精度。最终将该模型应用于高温合金的热等静压模拟,其变形模拟结果与实验相符,并且应力分布比传统Drucker-Prager/Cap模型的计算结果更加合理。

Abstract:

Powder Metallurgy is an important part of the forming process for metal materials. However, most material models are not able to simulate the variation of mechanical characters during the compressing process. In this paper, the Drucker-Prager/Cap model is modified by including the fully densified metal yield strength. This modified Drucker-Prager/Cap model can limit the yield strength of metal powder within the Von Mises surface of a fully densified metal. With the compressing process, the powder’s surface is infinitely close to Von Mises surface. By comparing of the model prediction and the published experimental results, this modified model works well in terms of accuracy. And, it is applied to the simulation of a hot isostatic pressing for a supper alloy. The prediction of the deformation as well as the stress distribution by this model is more accurate compared to the real test than that by the traditional Drucker-Prager/Cap model.