应力状态的分类 单向应力状态应力矩阵 单向应力状态 One Dimensional State of Stresses x y  x 单向应力状态 ( One Dimensional State of Stresses ) 应力状态的分类 单向应力状态应力矩阵           = 0 0 0 0 0 0  x 0 0 σ