变载条件下镍基单晶合金蠕变本构建模方法

针对镍基单晶合金在变载条件下的蠕变计算问题,基于“等损伤”假设提出了一种用于变应力/温度条件下的硬化准则,并与耦合损伤的蠕变模型相结合。采用Arrhenius对数关系式对蠕变应变速率进行温度内插,使之能够用于给定温度范围的蠕变计算。将上述蠕变模型编写为ABAQUS/UMAT用户子程序,利用DD3,CMSX-4,DD6和DDXX共4种单晶合金的蠕变试验数据,验证了子程序对不同温度和应力、不同晶体取向、变应力/温度条件下单晶合金蠕变曲线的模拟能力。结果显示：该蠕变模型能够精确模拟单晶合金在较宽温度范围和不同晶体取向的蠕变曲线;相比于传统蠕变模型,该蠕变模型更加简单有效,对于变应力/温度条件下单晶合金的蠕变行为具有较高的模拟精度;所开发的子程序可用于单晶涡轮叶片在变工况条件下的蠕变响应分析。

Creep Constitutive Modeling of Nickel-Base Single Crystal Superalloy under Varying Loading

Aiming at the creep calculation of Nickel-base single crystal (SC) superalloy under varying loading, based on the hypothesis of "equal damage", a new damage hardening criterion suitable for varying stress/temperature conditions was proposed. The hardening criterion was combined with the creep law coupling damage. The Arrhenius logarithmic relation was used to interpolate the creep strain rate according to the temperature to calculate creep in a certain temperature range. The above model was coded as ABAQUS / UMAT subroutine. The creep test data of DD3, CMSX-4, DD6 and DDXX were used to verify the ability of the model in simulating creep deformation under different temperatures and loads, different crystal orientations, varying stress/temperature conditions. The results show that the model can accurately simulate the creep deformation of SC superalloy at different temperatures and different crystal orientations. Compared with traditional models, the new creep model is simpler and more effective with higher accuracy for simulating the creep deformation of SC superalloy under varying stress and temperature conditions. The developed subroutine can be used to calculate the creep response of SC turbine blade under varying loading conditions.