多轴循环塑性双界面本构模型研究

Study on two-surface model in multi-dimensional cyclic plastic constitutive theory

地震作用具有很大的随机性和不确定性,为准确描述结构在强震作用下的弹塑性反应,基于循环塑性理论框架,提出了改进的双界面本构模型,对屈服面及边界面的平移运动和变形演化方程进行改进,并通过在塑性应变空间中引入一个记忆面来考虑材料对应变加载历史的硬化记忆效应。模型参数均可通过单轴拉伸及单轴滞回试验曲线标定。研究结果表明:该模型能准确地预测多轴任意路径加载下多晶体金属材料的屈服平台段、Bauschinger效应、循环硬化、棘轮效应、记忆效应等行为;将预测结果与各类金属及合金材料的试验结果进行对比,二者的最大正应力、剪应力的预测误差分别在2%、4%以内,验证了模型的适用性,其可为精细化弹塑性分析提供理论依据。

Seismic action is of great randomness and uncertainty. Based on the framework of cyclic plastic theory, a modified two-surface constitutive model was proposed to accurately describe the elastic-plastic response of structure in the earthquake. The equations of translational movement and deformation evolution of yield surface and boundary surface were improved. A memory surface in the plastic strain space was proposed to evaluate the hardening memory effect of the material caused by its strain loading history. All the model parameters can be obtained through uniaxial tension and hysteresis tests. It shows that the developed constitutive model permits an exactly good description of the behavior of multicrystal metal material under multi-dimensional random loadings, including yield plateau, Bauschinger effect, cyclic hardening, ratcheting effect and memory effect etc. The applicability of the model has been verified by comparing simulated results with various metal and alloy material test results. The prediction errors of maximum normal stress and shear stress are within 2% and 4%, respectively. It provides a theoretical basis for the sophisticated elasto-plastic analysis.