52弹性体的剪切形变 1.剪切形死剪划应力与应戏 力偶: F=-F F F 剪切应力:τ a 99 F ■口■■■■ F 力偶矩的平衡条件:(rac)b=(rbc)aF = - F’ ， F’’ = - F’’’ τ τ’ ： (τa c) b = (τ’b c) a → τ = τ’ F F F’’ ’’’ F’ a b c