空洞敏感材料轴对称超塑约束胀形的数值研究

NUMERICAL STUDY OF AXISYMMETRICAL RESTAINED BULGING WITH SUPERIMPOSED PRESSURE FOR CAVITY SENSITIVE SUPERPLASTIC MATERIALS

本文将含有变形损伤的本构关系引入大应变刚粘塑性有限元模型，研究空洞敏感材料轴对称起塑约束胀形的变形特性与损伤机制。讨论了材料速率敏感指数ｍ、空洞长大速率Ｄ０、静水背压力Ｐｈ、摩擦因子Ａｍ以及模具几何（宽高比ＲＤ／ＨＰ）对胀形件厚度不均匀性及空洞扩展的影响。

In this paper, a contitutive relation containing deformation damage is introduced into a rigid visco plastic finite element model for large strain problems. The superplastic deformation characteristics and the damage mechanism of axisymmetrical constrained bulging for cavity sensitive materials are numerically studied. The influences of the strain rate sensitive exponent m, the cavith growth rate D, the hydrostatic back pressure Ph, the friction factor Am and the die geometrical shapes (the ratio between the width RD and the height Hp) on the limit thicdness inhomogeneity and the cavity growth of bulged sheets are discussed in detail. Manners and methods improving the inhomogeneity and controlling the cavitation growth are proposed as well.