E、剪物(Axial Tension&Compression,shear) 3、强度条件(Strength condition) T= A Id为材料的许用切应力(Allowable 剪切面 shearing stress of a material) Il= n Tu-剪切极限应力 (ultimate shearing stress) n-安全系数(factor of safety)(Axial Tension & Compression，shear) 3、强度条件（Strength condition) [] 为材料的许用切应力(Allowable shearing stress of a material) (factor of safety) m m F 剪切面 F F m m  =    A FS n u  [ ] = n - 安全系数  u - 剪切极限应力 (ultimate shearing stress)