基于Bodner-Partom理论的FGH96合金本构建模研究

Study on Constitutive Model for FGH96 Superalloy Based on Bodner-Partom Theory

为研究某航空发动机涡轮盘典型材料粉末高温合金FGH96高温下的变形特性,基于Bodner-Partom(B-P)统一粘塑性本构理论对其高温下的力学行为进行本构建模。开展了550℃下的单轴拉伸及低周疲劳试验,利用Levenberg-Marquardt算法对模型参数进行了优化识别。采用隐式积分算法将本构方程离散为差分方程组,推导了一致切线刚度矩阵,为提高积分过程的精度和可靠性,引入以非弹性应变增量为度量的积分步长控制策略。通过用户子程序接口UMAT将B-P模型引入到ABAQUS有限元软件中进行数值模拟。结果表明:高温下FGH96材料表现出一定的率相关性及循环软化特性,模拟曲线与试验结果平均相对误差在10%以内,具有较好的一致性,说明B-P模型能够较好地模拟FGH96合金高温下的变形特性,验证了本实验模型与UMAT子程序的准确性。

In order to study the deformation characteristics of a typical material powder metallurgy superalloy FGH96 used in aeroengine turbine disk,the Bodner-Partom(B-P)unified viscoplastic constitutive theory was used to construct its mechanical behavior of FGH96 at high temperature.Uniaxial tension and low cycle fatigue tests were carried out at 550℃,and the model parameters were identified and optimized by Levenberg-Marquardt algorithm.In order to improve the accuracy and reliability of the integration process,an integral step control strategy based on inelastic strain increment was introduced.The B-P model was introduced into ABAQUS finite element software through the user material subroutine UMAT for numerical simulation.The results showed that the FGH96 superalloy exhibits a certain rate dependence and cyclic softening characteristics at high temperature.The average relative error between the simulation curve and the test results is less than 10%,which shows that the B-P model can better simulate the deformation characteristics of FGH96 superalloy at high temperature,and the accuracy of the model and the UMAT subroutine is verified.