45钢单轴应变循环软化行为的本构模型

为了更好地描述材料的循环软化行为,基于调质处理的45钢在对称与非对称应变循环加载下的变形特征,建立了其循环塑性本构模型.模型中考虑了材料在初始1/4循环加载时达到上屈服限后的应变软化现象.此外,用屈服面半径和背应力演化方程对后继循环软化行为进行了模拟.结果表明,在低周疲劳过程中,无论是循环软化滞回圈形状,还是循环应力幅值随循环周次的变化,理论预测与实验结果均吻合得很好.

Constitutive Model for Cyclic Softening Behavior of 45 Steel under Uniaxial Cyclic Straining

In order to describe the cyclic softening behavior ot materials more exactly, a cyclic plastic constitutive model was proposed based on the deformation character of quenched-tempered 45 carbon steel under symmetrical and unsymmetrical cyclic loadings. In this model, strain softening after the upper yield stress in the first 1/4 cycle is taken into account. In addition, the subsequent cyclic softening behavior was simulated by utilizing the evolution equations of yield radius and backstress. The research results show that the predicted results agree well with the experimental ones for the shape of cyclic softening hysteresis loops and the evolution of stress amplitude with cyclic number during the low cycle fatigue.