背表面 meaning in Chinese

back surface

When targets penetrated by flat - ended projectile , shear deformation along the penetration direction appears , at the same time compressive deformation also appears in the material that is in front of the projectile . the compressive deformation begins at the back surface of the target and spreads inward
钝头弹侵彻下，侧壁材料发生轴向剪切变形，同时，弹体前方的材料发生压缩变形，压缩变形首先在靶板背表面开始，而后自背表面向靶内传播。