在我国的材料力学教材和教学中,多数只讲授最大拉伸正应力理论、最大伸长线应变理论、最大剪应力理论、歪形能理论,以及莫尔强度理论.在讲授最大剪应力理论,即屈服准则 τ_(max)=(σ_1-σ_3)/2=c,亦即σ_1-σ_3=σ_s,时都要讲到,这个理论由于未考虑中间主应力σ_2对材料强度的影响而对材料在复杂应力状 In China’s material mechanics textbooks and teaching, most of them only teach the maximum tensile stress theory, the maximum elongation strain theory, the maximum shear stress theory, crooked energy theory and Moore strength theory.In the teaching of the theory of maximum shear stress, namely The yield criterion τ_max = σ_1-σ_3 / 2 = c, that is, when σ_1-σ_3 = σ_s, it should be mentioned that this theory does not consider the influence of the intermediate principal stress σ_2 on the material strength, Stress-like