空心车轴不同形状比裂纹应力强度因子的仿真研究

空心车轴在运用中可能会出现意外损伤而诱发表面裂纹。应力强度因子是预测裂纹扩展情况的重要参数。本文分析了空心车轴的运用载荷,根据所测载荷谱,采取有限元方法计算车轴横截面的应力分布情况。采用四分之一20节点等参退化奇异单元模拟裂纹前缘的应力奇异性,建立空心车轴表面裂纹扩展的有限元模型,并对裂纹前缘进行离散,实现正交扩展,得到不同步扩展的裂纹前缘。在此基础上对裂纹前缘不同位置的应力强度因子进行计算分析,得出不同初始形状裂纹前缘扩展中的应力强度因子分布规律。计算结果表明,具有不同初始形状的裂纹,随着裂纹的扩展,裂纹形状将趋于某一形状比范围内。与解析方法计算的结果比较,二者基本吻合。

The Finite Element Research of Stress Intensity Factors at Surface Crack Front of Hollow Axles

Accidental damages may occur on the surface of hollow axles of high-speed railway vehicles in running and this may induce surface cracks.The stress intensity factors are important parameters for estimating crack propagation.So the service loads of hollow axles are defined,and the stresses of hollow axle cross sections are obtained according to the load spectrum by finite element calculating.Quarter point 20-node isoparametric degenerative singular elements are used to simulate the stress singularity in the region near the crack tip.The finite element model of crack extension of hollow axles is established,and the crack front is dispersed to realize orthogonal extension.Based on this the stress intensity factors of the crack front are calculated,and the distribution rules of the stress intensity factors of different initial-shapes cracks are obtained.The results show that the crack tends to fall within a special aspect ratio scope with extension.The conclusions agree with the analytic results.