基于压磁效应的钢筋疲劳损伤试验研究

Experimental study on steel bars' fatigue damage based on piezomagnetism

对17个HRB400热轧钢筋加工的标准试件进行轴向拉伸疲劳试验,并通过实时记录试件周围的压磁信号,研究疲劳过程中压磁信号的演变规律.结果表明:HRB400钢筋的压磁信号对疲劳损伤很敏感,相比应力-应变滞回曲线更能反映疲劳损伤过程;在静力加载与循环加载过程中,压磁信号曲线都存在一个相对稳定的极值比;不同疲劳阶段的压磁滞回曲线存在显著差别,根据滞回曲线极值点的变化可预测疲劳失效;比较2个磁探头信号的曲线特征可初步判断失效的位置;试验得到的压磁信号演化过程符合疲劳三阶段规律,据此提出一个预测钢筋剩余疲劳寿命的方法.

Axial tensile fatigue tests of seventeen standard specimens machined by HRB400 hot-rolled bars were carried out and the piezomagnetic signals nearby them were real-timely recorded to analyze the evolution of piezomagnetism in fatigue of process.The experimental results demonstrate that the piezomagnetic signals of HRB400 bars are sensitive to fatigue damage,which can better indicate the fatigue damage process than stress-strain hysteresis loop.The piezomagnetic signal curve has a relatively steady extreme value ratio both in static loading and cyclic loading process.The piezomagnetic hysteresis loop curve changes significantly in different fatigue stages.The fatigue failure can be predicted according to the evolution of extreme points in hysteresis loop curve.The fracture position can be located preliminarily by the signal curve＇s characteristic of two magnetic probes. The obtained evolution process of the piezomagnetic signals agree with the three principal stages of fatigue,based on which the prediction method for the residual fatigue life of steel bars was proposed.