U75V钢轨钢耦合损伤循环塑性本构模型研究

Study on Damage-coupled Cyclic Plastic Constitutive Model of U75V Rail Steel

针对我国重载铁路和地铁用钢在实际服役过程中的全寿命棘轮行为,开展U75V钢轨钢耦合损伤循环塑性本构模型研究。首先通过不同平均应力和不同应力幅值的循环实验,研究U75V钢轨钢在室温下的全寿命棘轮行为;然后基于损伤力学和循环塑性框架,采用损伤修正的Chaboche随动硬化模型,引入指数型损伤演化律,建立耦合损伤的循环塑性本构模型;最后针对材料的失效模式,建立基于损伤临界值的疲劳失效判据,预测失效寿命。研究结果表明,模拟循环稳定时的棘轮应变率误差小于22.0%,失效时的棘轮应变误差小于38.0%;预测U75V钢轨钢的低周疲劳寿命均在1.5倍误差带内。总的来说,该耦合损伤循环塑性本构模型能描述U75V钢轨钢在非对称单轴应力循环下的全寿命棘轮行为。

In order to address the whole-life ratcheting behavior of U75V rail steel for heavy-haul railways and subways in China,the damage-coupled cyclic plastic constitutive model of U75V rail steel is investigated in this paper.Firstly,the whole-life ratcheting behavior of U75V rail steel at room temperature is studied through cyclic experiments with different average stresses and different stress amplitudes;subsequently,a damage-coupled cyclic plastic constitutive model is proposed in the framework of damage mechanics and cyclic plasticity.The proposed model incorporates the damaged-coupled Chaboche kinematic hardening model and exponential damage evolution law.Finally,based on the observed failure modes of the material in the experiments,the critical value of the damage variable is adopted as the fatigue failure criterion for predicting the failure life.Results demonstrate that when the cycle is stable,the simulated ratcheting strain rate error is below 22.0%,while it reaches 38.0%during cycle failures.The predicted fatigue life of U75V rail steel falls within the 1.5 times error band.Overall,the developed damage-coupled cyclic plastic constitutive model effectively describes the whole-life ratcheting behavior of U75V rail steel subjected to cyclic asymmetric uniaxial stress loadings.