一种自紧厚壁圆筒非线性混合硬化模型及残余应力分析

为准确地计算自紧身管强度及疲劳寿命，建立一种能反映其非线性应力与应变关系和包辛格效应等性能的材料本构模型，用以提高残余应力计算精度。基于非线性随动硬化模型，建立一种适用于表征自紧身管力学性能的非线性混合硬化模型，通过数值计算可获得残余应力分布情况；为提高数值计算的收敛速度，结合所建立的材料本构模型和各参量间的弹塑性关系，推导了与本构模型密切相关的一致切线刚度矩阵；为验证该本构模型的正确性，综合运用拉压试验和优化算法确定材料参数，进行了自紧身管残余应力有限元数值计算及分析。结果表明：数值计算的残余应力分布曲线与试验数据基本吻合；建立的炮钢本构关系模型能真实反映自紧厚壁圆筒的残余应力分布情况。

A Nonlinear Combined Hardening Model for Residual Stress Analysis of Autofretted Thick-walled Cylinder

In order to compute the strength and fatigue life of autofretted barrel exactly, a constitutive model which can reflect the material characteristics of gun steel, including Bauschinger effect and the nonlinear relationship between stress and strain, is constructed for improving the calculating accuracy of residual stress. On the basis of a nonlinear kinematic hardening model, a nonlinear combined hardening model which is used to describe the mechanical properties of autofretted barrel and calculate the residual stress distribution is proposed. According to the proposed constitutive model and the elastic-plastic relationship among parameters, a tensor-form consistent tangent modulus related to the constitutive model is derived for increasing the convergence speed of numerical calculation. To verify the constitutive model, the material parameters are determined by combining the tension compression tests and optimization algorithm. The residual stress of autofretted barrel is calculated by utilizing these parameters and FEA method. The difference between the calculated and experimental results is small. The results show that the proposed constitutive model can reflect the residual stress distribution of autofretted thick-walled cylinder effectively.