循环荷载下奥氏体型和双相型不锈钢材料本构关系研究

为研究循环荷载下不锈钢材料的本构关系，对奥氏体型S30408不锈钢和双相型S220503不锈钢材料进行了单调拉伸和大应变超低周循环加载试验。采用三种常用的单调拉伸本构模型对所得应力-应变曲线进行拟合，得到相应单调荷载下材料本构参数；采用Ramberg-Osgood本构模型对循环骨架曲线进行拟合，得到材料循环强化参数；利用Chaboche塑性本构模型，标定了两种材料的循环本构参数。结果表明：在单调拉伸荷载下，G-R-O本构模型更适用于拟合不锈钢材料的单调拉伸本构；在循环荷载下，不锈钢材料滞回曲线饱满，且随着应变增大，两种材料在加载后期均表现出了明显的循环强化现象；Ramberg-Osgood本构模型对骨架曲线拟合较好，有限元计算结果和试验滞回曲线吻合度高；表明该文标定出的强化参数、循环本构参数可用于结构体系地震响应分析之中，为准确分析不锈钢结构在地震作用下的受力性能提供参考。

STUDY ON CONSTITUTIVE MODEL OF AUSTENITIC STAINLESS STEEL AND DUPLEX STAINLESS STEEL UNDER CYCLIC LOADING

In order to study the constitutive relation of stainless steel under cyclic loading, austenitic stainless steel S30408 and duplex stainless steel S220503 coupons were tested under monotonic and large-strain ultra-low cyclic loading. Three types of constitutive models were used to fit the stress–strain relationship under monotonic loading, and pertinent constitutive relation parameters were obtained. The cyclic skeleton curves were fitted by the Ramberg-Osgood model, and the parameters of the cyclic hardening were calculated. Furthermore, the parameters of the cyclic constitutive model were calibrated and the test curves were simulated by ABAQUS finite element analysis software. The results show that the G-R-O constitutive model can fit the constitutive relation better under monotonic loading. Under cyclic loading, with the increase of cyclic loops and change in strain amplitudes, stainless steel exhibits a cyclic hardening behavior. The Ramberg-Osgood model fit the skeleton curve well and the simulated curves agree fairly well with the test curves. Therefore, the hardening parameters and cyclic constitutive parameters which calibrated by the test data can be applied to the structural seismic analysis, and improve the accuracy of analysis for the stainless steel structure under earthquake.