疲劳多裂纹扩展的常规态型近场动力学分析

Ordinary state-based peridynamics method for fatigue multi-crack propagation

摘要:

为改进疲劳多裂纹扩展问题的分析,建立了常规态型近场动力学的疲劳多裂纹扩展模拟方法.在常规态型近场动力学的理论框架基础上,采用近场动力学疲劳裂纹萌生和扩展模型,建立了一个可模拟疲劳裂纹萌生与扩展的平面应力近场动力学模型.针对近场动力学疲劳模型计算量庞大的问题,又引入“临界断裂数”来优化模型的计算流程,提升模型的计算速度,以单边裂纹板为研究对象,通过选取不同“临界断裂数”的值寻求计算效率与裂纹路径精准度之间的平衡.从计算结果的对比中可以发现,当采用恰当的“临界断裂数”时,计算速度得到了较大的提升,同时裂纹仍能保证精准的形状.然后,该模型被用于非共线多裂纹板的疲劳破坏模拟仿真之中,当采用不同的“临界断裂数”时,计算运行得到的疲劳裂纹扩展路径以及相应的a-N曲线均能与实验得到的结果取得良好的吻合.研究结果表明,近场动力学疲劳分析方法不需引入断裂准则和预知裂纹路径,裂纹可以任意扩展.

Abstract:

To improve the analysis of fatigue multi-crack propagation problem, a method for fatigue multi-crack propagation simulation based on ordinary state-based peridynamics was established. Based on ordinary state-based peridynamics theory, a plane stress peridynamics model for fatigue crack initiation and propagation was proposed by using peridynamics fatigue theory. Due to the large amount of calculation for the peridynamics fatigue model, a parameter named “critical broken bonds number” was introduced to the model to speed up computation. The balance between computational efficiency and suitable crack path accuracy was studied with different “critical broken bonds number” based on an edge-cracked panel. Results show that the calculation was speeded up when an appropriate broken bond number was used, and the crack extention road also kept a precise shape. The fatigue crack of panel with multiple cracks was simulated by the peridynamics fatigue model with different “critical broken bonds number”, and the fatigue crack paths and a-N curve agreed well with the experimental result. Results show that fatigue crack can propagate arbitrarily by the suggested peridynamics fatigue model without setting extra crack extension criteria or preset crack routes, and it significantly improves fatigue multi-crack propagation simulation.