金属磁记忆检测技术定量评估构件疲劳损伤研究

Research on Quantitative Assessment of Fatigue Damage by Metal Magnetic Memory Methods

对18CrNi4A钢缺口试件在三级应力水平下进行疲劳试验和磁记忆信号检测,研究金属磁记忆信号在疲劳过程中的变化规律和磁记忆检测技术对构件疲劳损伤的定量估评。结果表明:在稳定循环阶段,磁信号随疲劳循环周次增加无显著改变,疲劳裂纹萌生后,磁信号逐渐增加,并在断裂后发生激变;磁信号特征参量Kmax,Hp(y)max,Hp(y)min和Hp(y)sub值与应力水平和疲劳损伤程度存在强烈的相关性,特征参量绝对值随应力水平或疲劳损伤程度的增加而逐渐增加;磁信号特征参量Kmax平均值法可较准确地定量评估构件疲劳损伤,该方法判据为:当m(m=Kmax/KAmaVx)>1,试件存在严重的疲劳损伤。

Fatigue tests of notched 18CrNi4A steel specimens were carried out under three different fatigue stresses and metal magnetic memory （MMM） signals were detected. The variation of the MMM signals and the quantitative assessment of fatigue damage by MMM methods were investigated. The results show that the variation of the MMM signals is unobvious before the cracks initiate, but the MMM signals increase obviously with the propagation of the cracks and vary abruptly after rupture. There is an inherent relationship between the fatigue stress and the feature parameters K Hp（y） Hp（y）min and Hp（y）sub, the larger the fatigue stress or fatigue damage is, the larger the absolute values of the feature parameters are. The fatigue damage can be assessed effectively by obtaining the average value of K The basis of this method is that if the value of rn（m=Kmax/Kmax^AV）is larger than 1, there will be serious fatigue damage.