判别主方向的剪应力指向判别法

A Method of Determining the Principal Direction According to the Shear Stress Direction

采用剪应力指向判别平面应力状态两个主应力与主方向之间的对应关系，无需记忆任何规则或约定。

Students needn't remember any rules or appointment when distinguishing the corresponding relation between the principal stress and principal direction in the plane stress state according to the shear stress direction. The method is visual and accurate. [