基于晶体塑性的涡轮盘短裂纹扩展模拟方法

针对低周疲劳载荷下发动机涡轮盘早期短裂纹扩展行为，提出适用于工程结构的耦合晶体塑性（CP）理论和扩展有限元方法（XFEM）的多晶短裂纹模拟方法。该方法采用晶体内总累积分解切应变作为裂纹扩展判据并使裂纹沿最活跃滑移系对应的滑移平面传播。框架采用子模型技术/分区域网格细化以及宏-介观本构结合的方法解决真实工程结构和微观模型尺度不匹配的问题，在可接受的计算代价下预测了涡轮盘危险截面处的短裂纹扩展路径及速率。结果表明该结构内早期裂纹生长路径及速率受到晶体取向的影响而出现较大分散性，同时验证了基于CP-XFEM的框架在预测工程结构短裂纹扩展寿命及分散性上的可行性。 

Simulation method of short crack propagation in turbine disks based on crystal plasticity

In view of the early-stage short crack propagation behaviour in turbine disks under low-cycle fatigue，a method coupling crystal plasticity （CP） theory and extended finite element method （XFEM） was proposed to simulate short cracks in engineering structures.The method used the total cumulative shear strain in crystals as the criterion of crack propagation and made the crack propagate along the slip plane with the most active slip system.By using sub-model technology/regional refinement of grids and a combination of macro-micro constitutive models，the framework overcame the scale mismatch between the real engineering structure and the micro model，and then predicted the short crack propagation path and rate in the dangerous section of a technique turbine disk at an acceptable calculation cost.The results showed that the short crack propagation path and rate in structures was highly affected by crystal orientations，resulting in a large dispersion of fatigue life.At the same time，it verified the feasibility of the CP-XFEM-based framework in predicting the short crack propagation life of engineering structures.