塑性变形中的两种损伤

本文对由微孔洞定义的损伤D~A和由弹性模量下降定义的损伤D~E进行了分析,发现两者在量值,各向同异性和不可逆性三方面均存在差异,认为它们是两个完全不同的量。文中指出现行损伤理论中的假设和模型是有缺陷的。为此,本文提出了一种二元损伤模型,使得现行损伤理论存在的一些矛盾得到了较为合理的解决。文中还讨论了受损材料的本构方程和两种损伤应变能释放率。

Two Kinds of Damage in Plastic Deformation

The differences in magnitude, in anisotropy and isotropy, and in irreversibility between scalar damage DA (defined by micro cavities)and tensor damage DE (defined by modulus of elasticity) is discussed. It has been found that DA and DE are two completely different kinds of damage. It is pointed out that there are shortcomings in Lemartre's hypothesis of strain equivalence, Sidoroff's hypothesis of strain energy equivalence and Murakami's anisotropic damage model. By using DA and DE as two internal variables, a dual damage model With which the existing damage theory is improved is proposed. The constitutive equation for damaged material and two damage strain energy release rates are also discussed.