孔洞敏感超塑性材料变形的数值分析

本文用两种数值方法,非线性长波分析和刚粘塑性有限元方法研究了孔洞敏感的超塑性材料在单向拉伸和园板涨形中的不均匀变形和断裂过程。分析表明,这种过程是不均匀几何失稳与内部孔洞长大的结合与相互作用的结果。材料的应变速率敏感性指数与孔洞长大速率通过不同的变形机理图控制着这种过程。叠加的静水压力能够改变孔洞敏感材料的断裂模式,从常压下没有宏观颈缩的孔洞断裂到无内部孔洞的外部颈缩断裂。

Numeric Analysis of Superplastic Deformation in Gavity-Sensitive Material

In this paper,the development of non-uniform deformation and the proc- ess of fracture in cavity-sensitive superplastic material under uniaxial tension and circulat sheet bulging are numerically analyzed by using both the one-di- mensional approximate analysis and the rigid-viscoplastic FEM.The analysis shows that the process is the result of the comaination of the non-uniform geo- metric-instability and the internal cavity growth,and the interaction on each other.It is controlled by the sensitive index of the strain rate and the cavity growth rate of material.The fracture mode can be changed by a superimposed pressure,from the fracture without external necking at the constant pressure to the fracture with necking development or extensive thinning at a pressure large enough to completely suppress cavity growth.