课堂测试(3) m 解:围绕A点取一个单元体 0m0x+6+1( 45 T 2 tan 20 ao →a0=-45ax1=45 O.-0 1+.t E 10 E 1+μE1 4 E 2 GP 2(1+m)2E1261Wx  y m m A 45° x -45° 解：围绕A点取一个单元体 x x x y x y τ τ σ σ σ σ σ σ + =  − + + = 2 2 min max ) 2 ( 2 = − − − = x y x σ σ τ α 2 tan 2 0 x τ E μ σ μσ E ε  + = − = 1 ( ) 1 1 1 3 x x σ = τ σ = σ = −τ 1 2 0 3  45 α0 = −  α1 = 45 1 1 ε τ μ E x = + 1 1 1 1 80.2 GPa 2(1 ) 2 2 x t E m G = +m W    =  =  = 课堂测试（3）  1  3 A