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采用Voronoi图,生成具有随机晶粒形状的三维多晶集合体模型,并赋予每个晶粒相应的取向。基于率相关晶体塑性理论,开发了用户材料子程序,并将其嵌入有限元软件中模拟面心立方多晶集合体在单轴单向拉伸过程中的应力-应变响应,分析了网格细化及晶粒取向对模拟结果的影响。研究表明,随网格细化应力值有所降低,但变化不大,为保证结果的可靠度,平均每个晶粒离散的单元数目在5个以上;随多晶集合体中晶粒数目的增加,由于取向的随机性产生的应力-应变的差异逐渐减小,模拟时多晶集合体中晶粒的数目大于50个;模型较好的反映了材料的真应力随应变速率增加而增大的规律,且模拟结果和实验结果吻合良好,说明该模型具有较高的可靠性。
Using the Voronoi diagram, a three-dimensional polycrystalline aggregate model with random grain shapes is generated and given the corresponding orientation of each grain. Based on the rate-dependent crystal plasticity theory, a user material subroutine was developed and embedded in finite element software to simulate the stress-strain response of a face-centered cubic polycrystalline aggregate during uniaxial uniaxial tensioning. Effect of Grain Orientation on Simulation Results. The results show that, with the grid refinement, the stress value decreases slightly, but the change is insignificant. In order to ensure the reliability of the result, the average number of discrete elements per crystal grain is more than 5; with the number of crystal grains in the polycrystalline aggregate Increases, the difference of stress-strain due to the randomness of orientation decreases gradually, and the number of grains in the polycrystalline aggregate is greater than 50 during the simulation. The model better reflects that the true stress of the material increases with increasing strain rate The simulation results agree well with the experimental results, which shows that the model has high reliability.