国产钢材LYP225的低周疲劳试验研究

Experimental study on low-cycle fatigue behavior of Chinese LYP225

目前,对于低屈服点钢材的低周疲劳性能试验的研究不多。对两组不同尺寸的国产低屈服点LYP225钢材进行低周循环加载试验,研究其循环骨架曲线、滞回环特点、低周疲劳寿命等特性;同时探讨长细比对低屈服点钢材疲劳寿命的影响。通过Ramberg-Osgood模型对不同应变幅加载下的滞回环进行拟合,得出钢材循环骨架曲线;通过Coffin-Manson模型拟合得到钢材的低周疲劳寿命S-N(应变-寿命)曲线;通过试验数据确立了混合强化参数并将其输入ABAQUS软件中,所得结果能很好地模拟LYP225钢材的滞回曲线。试验结果表明:国产LYP225钢材滞回环饱满,表现出良好的延性,低周疲劳特性好于国外相同试样尺寸的同等级钢材;国产LYP225钢材低周疲劳寿命受试样长细比的影响较大,相同应变幅下,长细比越大其低周疲劳寿命越低;通过试验数据拟合得到的强化参数可用于构件在整体结构中的地震反应分析。

At present, the research on low cycle fatigue of low-yield-point steel LYP225 was rarely mentioned. To better investigate the properties and behavior of low-yield-point steel, experiments of two groups of different dimensions of specimens were carry out. All of the specimens were tested under monotonic loading and cyclic loading. This paper presented the results, like the skeleton curve, hysteresis loops, low cycle fatigue life and so on. The influence of slenderness ratio on the fatigue life of low-yield-point steel was also discussed. To simulate the skeleton curves, Ramberg-Osgood model was applied. Moreover, the low cyclic fatigue life （S-N） curves were based on Coffin-Manson model. The combined hardening parameters, extracted from the experimental data, were input in the finite element models, whose simulation results agreed well with the experimental hysteretic curves. The results showed that Chinese LYP225 has plumper hysteresis loops and better ductility and fatigue properties than the foreign steel in the same dimension and grade. Chinese LYP225 is more sensitive to the impact of slenderness ratio. Under the same strain amplitude, the low cycle fatigue life became shorter with higher slenderness ratio. The calibrated hardening parameters based on the test data can be further used in the seismic analysis of structural members.