微观结构下多晶材料的疲劳损伤模型及裂纹的数值模拟方法

Model for Fatigue Damage and Numerical Simulation Method of Cracks for Polycrystalline Material under Microstructure

考虑多晶材料疲劳行为受晶粒拓扑结构的影响,建立了多晶材料Voronoi镶嵌的有限元微观结构模型,并在Voronoi边界插入内聚力单元模拟晶界特性。在此基础上,基于Abaqus双线性内聚力本构关系,建立了内聚力单元的疲劳累积损伤模型,定义了损伤变量,损伤判据以及损伤规律;通过Abaqus UMAT(User-defined material mechanical behavior)子程序编写了内聚力单元疲劳损伤的数值计算程序,实现了对微观结构下材料滚动接触疲劳裂纹萌生与扩展的行为模拟。以滚子与滚道的接触疲劳分析为例,将数值模拟结果与实测结果相比,表明了该数值仿真方法模拟多晶材料裂纹形成和扩展的有效性。

Considering the fatigue behavior of polycrystalline material affected by grain topology,the finite element model for microstructure with Voronoi tessellation algorithm is established,and the grain boundary characteristics is simulated by inserting the cohesive elements.Then,based on the constitutive relationship of Abaqus bilinear cohesive force,the model for fatigue cumulative damage of cohesive element is established,and the damage variable,damage criterion and damage law are defined.The fatigue damage of cohesive elements is calculated with Abaqus User-defined material mechanical behavior.The calculation program realizes the behavior simulation of the rolling contact fatigue crack initiation and propagation under the microstructure.Finally,the contact fatigue analysis of the roller and the raceway is taken as an example.The simulation results are compared with the measured,which shows the effectiveness of the simulation method in simulating the formation and propagation of cracks for polycrystalline materials.