一种新的应力率定义

本文研究客观应力率的定义及表示,在放弃了客观应力率形式上的对称性以后定义了一类广义的非对称的客观应力率。从Cauchy应力原理出发,通过构造应力向量形式上和变形及变形率无关的客观导数,得到两种形式的应力率;它们表示作用在参考构形中单位物质面元应力向量的真实变化,这样就消除了应力率定义中的不确定性。用新应力率对次弹性体简单剪切进行了计算,得到的应力不振荡,且满足超弹性正应力-剪应力普适关系。

A NEW KIND OF OBJECTIVE STRESS RATE

The paper deals with the definition and representation of objective stress rates. At first the requirement in symmetry to the form of the objective stress rates is given up and a family of generalized stress rates is defined. From the Cauchy fundamental principle of stress, two new unsyrnmetric objective stress rates are derived through objective rates of stress vectors, these rates are in form independent of deformation and deformation rate. The new objective stress rates represent the true change of the stress vector exerted on a unit area element in rtference configuration. This the incietermination in the definition of the objective stress rate can be removed. The new stress rate is applied to a hypoelastic body experiencing simple shear, there is no oscillation in the stresses and the general normal stress-shear stress relation for superelasticity is also satisfied.