A simple normal or direct stress produces a certain elongation or contraction of the material. 单纯的正应力使材料产生一定的伸长或缩短。
The condition of uniaxial stress is closely approximated in prismatic bars subjected to pure axial tensile or compressive ioading. 承受单纯轴向拉伸和压缩的棱柱杆十分近似地处于单轴的应力状态。
