不同复合比下不锈钢复合钢材循环本构模型研究#br#

为研究不同复合比下不锈钢复合钢材在地震循环往复荷载作用下的力学特性，开展23个3+3mm厚316L+Q235B不锈钢复合钢材试件的单调拉、压和15种不同循环加载制度下的试验。根据试验结果，分析该类复合钢材的单调性能、滞回性能以及宏观和微观破坏形态；基于Ramberg-Osgood三参数模型拟合循环骨架曲线，并讨论其与单调荷载下的力学性能区别；基于Chaboche模型标定该不锈钢复合钢材的本构模型参数，并采用数值模型对其他循环加载制度下的力学响应进行模拟；最后与3+5mm厚316L+Q235B不锈钢复合钢材在循环骨架曲线、循环本构关系及滞回曲线方面进行对比，分析复合比的影响。试验结果与分析表明：该种复合比的不锈钢复合钢材在循环荷载下仍表现出明显的循环强化作用和混合强化（等向强化和随动强化）特征；滞回曲线饱满；随着循环周次的增加，卸载刚度和再加载曲线的初始刚度出现明显退化；Ramberg-Osgood模型可以较好地对其循环骨架曲线进行拟合；文章提出的循环本构模型能够准确模拟该复合比不锈钢复合钢材循环往复荷载作用下的力学响应；该复合钢材与3+5mm厚316L+Q235B不锈钢复合钢材在循环荷载下的具体力学指标存在明显区别。研究成果为提出双金属复合钢材的统一循环本构模型提供重要基础。

Study on cyclic constitutive model of stainless-cladding bimetallic steel with different cladding ratios

 In order to study the mechanical response of stainless-cladding (SC) bimetallic steel with different cladding ratios under earthquake, tests of 23 specimens made of 316L+Q235B SC bimetallic steel with a thickness of 3+3mm were conducted under monotonic tension and compression loading as well as 15 different cyclic loading systems. The monotonic and cyclic behavior, macro-failure and micro-failure modes are analyzed. The cyclic envelop curves are fitted by using the Ramberg-Osgood three-parameter model and compared with the monotonic tensile curves. Based on the Chaboche plastic constitutive model, relevant parameters for the SC bimetallic steel are calibrated, and the tests are simulated numerically. Comparative analysis, such as steel with different cladding ratios on cyclic envelop curve, cyclic constitutive relation and hysteresis curves are carried out. The experimental results show that the SC bimetallic steel with larger cladding ratios still exhibits significant cyclic strengthening under cyclic loading. Mixed hardening characteristics are observed, including isotropic and kinematic hardening. The hysteretic curves are plump. With an increase of cyclic number, unloading stiffness and initial stiffness of the reloading curves are significantly degraded. The Ramberg-Osgood model fits the cyclic envelop curves well. The constitutive model proposed herein is proved good for simulating the cyclic responses of the SC bimetallic steel. The specific mechanical indexes of the SC bimetallic steel and 3+5mm thickness 316L+Q235B SC bimetallic steel under cyclic loading are significantly different. The research results provide an important basis for developing a uniform cyclic constitutive model of the advanced bimetallic steel.