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过去应用的铁路大型平车车耳孔强度计算方法,为经典力学的薄环或厚环理论。导出的最大应力断面的弯矩公式,薄环为M_B=Pr/2(1-2/π),厚环为M=PR/2(1-2/π+2e/πR)。而机械工程常用的别尔卡尔德厚环应力公式则为σ=(M/W)K+σ_e。上述理论均认为,与外载荷相垂直断面是最大应力断面。但是,D_(20)、D_(45)等大型车车耳孔的实验应力表明:最大应力断面引前经典理论断面约10°～20°,且该断面的应力值,比经典理论断面应力值约大20～30％。应用平面应力有限元法,将车耳划分为368个节点,639个单元,耳孔外载荷按正弦分布,电算结果符合试验结果。可知,平面有限元法可以应用于某些车辆结构的实际设计。
In the past, the method of calculating the ear hole strength of a large flat car used in railway vehicles was a thin ring or thick ring theory of classical mechanics. The bending moment formula of the maximum stress section derived is M_B = Pr / 2 (1-2 / π) for thin ring and M = PR / 2 (1-2 / π + 2e / πR) for thick ring. However, the commonly used Bezcald thick-ring stress formula in mechanical engineering is σ = (M / W) K + σ_e. The above theory is that the vertical section with the outer load is the maximum stress section. However, the experimental stress in the ear holes of large car such as D 20 and D 45 shows that the maximum theoretical cross-section of the maximum stress section is about 10 ° ~ 20 °, and the stress value of this section is larger than that of the classical theory section 20 to 30%. The plane stress finite element method is used to divide the ear of a car into 368 nodes and 639 units. The external load of the ear hole is distributed in the sine. The calculation result accords with the test result. It can be seen that the planar finite element method can be applied to the actual design of some vehicle structures.