吊钩是起重机的重要零件,当吊载物品时,吊钩钩身的曲线部分处在复杂的应力状态下。我们熟知并常用的吊钩断面形状是梯形断面如图1所示。A-B是危险断面,在这个断面上,拉力和弯矩的数值最大。断面上的法向应力由拉伸应力和弯曲应力所合成,内侧应力为σ拉十σ弯,外侧应力为σ拉-σ弯。从图1(b)可见,断面上内外侧应力合成后的差值很 Hooks are an important part of a crane. When lifting an item, the curved part of the hook body is under complex stress conditions. We are familiar and commonly used hook cross-section shape is trapezoidal section shown in Figure 1. A-B is a dangerous section, in this section, the maximum value of tension and bending moment. The normal stress on the cross-section is composed of tensile stress and bending stress. The stress in the inside is σ = 10 ° and the stress in the outside is σ = σ. As can be seen from Fig. 1 (b), the difference between the internal and external stresses on the cross section is very high