Finite element procedures for the numerical simulation of fatigue crack propagation under mixed mode loading
Finite element procedures for the numerical simulation of fatigue crack propagation under mixed mode loading
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DOI：
10.12989/sem.2010.35.3.283
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发表时间：
2010-06-20
影响因子：
2.2
通讯作者：
Alshoaibi, Abdulnaser M.
中科院分区：
文献类型：
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作者：
Alshoaibi, Abdulnaser M.
本文采用一种新的有限元软件对任意二维几何形状在恒幅载荷作用下的疲劳裂纹扩展进行了数值模拟。该软件的目的是确定二维裂纹路径和表面，以及评估部件寿命作为损伤容限评估的一部分。在整个疲劳裂纹扩展模拟过程中，在裂纹前节点附近和代表较高应力分布的单元中进行了自动自适应网格划分。在裂纹尖端奇异元的促进下，采用位移外推法估计了每个小裂纹增量处的疲劳裂纹方向和相应的应力强度因子。在线弹性断裂力学（LEFM）假设下，由应力强度因子决定的连续线性扩展模型的传播。应力强度因子范围历史必须沿着小裂纹增量记录。在完成应力强度因子范围历史记录后，预测试样的疲劳裂纹扩展寿命。为此提出并实现了一致传递算法和裂纹松弛方法。用相关实验数据和其他研究人员的数值结果验证了预测疲劳寿命的正确性。结果表明，该程序能较好地模拟疲劳寿命预测结果和疲劳裂纹路径。
This paper addresses the numerical simulation of fatigue crack growth in arbitrary 2D geometries under constant amplitude loading by the using a new finite element software. The purpose of this software is on the determination of 2D crack paths and surfaces as well as on the evaluation of components Lifetimes as a part of the damage tolerant assessment. Throughout the simulation of fatigue crack propagation an automatic adaptive mesh is carried out in the vicinity of the crack front nodes and in the elements which represent the higher stresses distribution. The fatigue crack direction and the corresponding stress-intensity factors are estimated at each small crack increment by employing the displacement extrapolation technique under facilitation of singular crack tip elements. The propagation is modeled by successive linear extensions, which are determined by the stress intensity factors under linear elastic fracture mechanics (LEFM) assumption. The stress intensity factors range history must be recorded along the small crack increments. Upon completion of the stress intensity factors range history recording, fatigue crack propagation life of the examined specimen is predicted. A consistent transfer algorithm and a crack relaxation method are proposed and implemented for this purpose. Verification of the predicted fatigue life is validated with relevant experimental data and numerical results obtained by other researchers. The comparisons show that the program is capable of demonstrating the fatigue life prediction results as well as the fatigue crack path satisfactorily.