运动学涡度、极摩尔圆及其在一般剪切带定量分析中的应用

自然界中剪切带通常是由平行于剪切带方向的简单剪切和与之垂直的纯剪切共同作用的结果。利用运动学涡度(W_K)可以定量地分析两者间的比值大小。一般摩尔圆只能应用于共轴应变,而极摩尔圆可应用于共轴与非共轴变形,并为求取W_K提供了一种简便可行的方法。本文对一般剪切带的概念及其分类进行了描述,对运动学涡度和极摩尔国的原理及其应用进行了系统的论述,并在此基础上提出了几种新的实用的极摩尔国编制方法。 

KINEMATIC VORTICITY, POLAR MOHR CIRCLE AND THIER APPLICATION IN QUANTITATIVE ANALYSIS OF GENERAL SHEAR ZONES

Most of shear zones in nature are results of co-actions of simple and pure shears and called general shear zones.A general shear zone can be narrowed or broadened. The relationship between simple and pure shears, and the change of shear zones in thickness can be analysed quantitatively by the method of kinematic vorticity (W_K) and polar Mohr circle. The kinematic vorticity is a measure of the non-coaxiality in progressive deformation history and, therefore, is the ratio of the pure shear to simple shear of a general shear zone.
W_K=cos (v), where v is the angle between the two eigenvectors in a shear zone. For a pure shear, v=90°, W_K=0;for a simple shear, v=0°, W_K=1;and for a general shear, 0° < v < 90°, 0 < W_K < 1. A polar Mohr circle, which can be constructed with some more practical methods presented by this paper f provides a convenient and feasible method for measuring v.
Once a polar Mohr circle is constructed, the angle (v), kinematic vorticity (W_K), ratio of the strain-rates (ε/γ)and the change of thickness of a shear zone can be obtained.