基于晶体塑性模型与内聚力单元模拟的接触疲劳亚表面原奥晶界裂纹萌生

Simulation of Subsurface Crack Initiation at Original Austenite Grain Boundaries Under Rolling Contact Fatigue Using Crystal Plasticity and Cohesive Elements

材料在接触疲劳载荷下亚表面裂纹的萌生是其主要损伤模式之一.采用晶体塑性模型耦合内聚力单元,模拟高强钢在滚动接触疲劳载荷下亚表面原奥氏体晶界处的疲劳裂纹萌生.基于内聚力模型的损伤起始准则和疲劳损伤演化规律,并利用USDFLD子程序将内聚力单元的疲劳损伤与晶体塑性模型结合,计算了滚动接触疲劳加载下的损伤随循环次数的累积.对Voronoi模型下的疲劳裂纹萌生进行了模拟,研究了晶体取向对裂纹萌生的影响.结果表明,裂纹的萌生受剪切应力主导,萌生位置在最大剪切应力范围内,模拟结果和试验观察一致.晶粒取向对裂纹萌生位置与萌生寿命有显著影响.

Subsurface crack initiation is one of the primary damage modes for materials under rolling contact fatigue.A crystal plasticity model combined with the cohesive zone elements is used to simulate the subsurface fatigue crack initiation at original austenite grain boundaries in a high strength steel.Based on the cohesive zone model of damage initiation criterion and fatigue damage evolution law,the damage accumulation with the number of cycles was calculated utilizing the crystal plasticity model in conjunction with the USDFLD subroutine.The fatigue crack initiation in the Voronoi model is simulated,and the effect of the crystal orientation on the crack initiation is investigated.The results indicate that the crack initiation is dominated by the shear stress,and the initiation position is within the range of maximum shear stress.The simulation results are consistent with the experimental observations.The grain orientation has a significant impact on the crack initiation location.