基于磁导率检测技术的应力集中和疲劳损伤检测

磁导率检测技术是依据探头闭合磁路中感应电压与磁通量的变化率成正比的电磁感应原理来检测试件磁导率变化的评价方法。此种方法高精度检测构件某区域与磁导率相关的各种变化,如应力集中、疲劳损伤、老化蜕变等。从磁路欧姆定律出发,推导分析了检测方法和检测原理。以Q235钢和45号钢为例,从试验上研究了检测信号随拉应力、拉力残余应力和疲劳损伤程度的变化关系。试验发现,依据磁导率检测技术,可有效测量铁磁材料试件所处的应力状态,判断构件曾经受过的最大应力。依据应力作用后的残余应力,测量构件曾经受过的最大应力具有更高的检测灵敏度。试验结果表明,对疲劳损伤的检测灵敏度低于对应力集中的检测灵敏度;对低碳钢Q235的疲劳损伤检测灵敏度大于对中碳钢45号钢的检测灵敏度。

Stress concentration and fatigue damage detection based on permeability testing technology

Permeability detection technology is an evaluation method to test specimen permeability change based on the electromagnetic induction principle which induced voltage is proportional to the change rate of flux in the closed magnetic circuit of probe.The detection technology can precisely detect the changes of parameters including stress concentration,fatigue damage,aging and decay,etc.Based on the Ohm′s law of magnetic circuit,the detection method and principle were deduced and analyzed.Taking Q235 and 45 steel as examples,relationship among the detection signal,the tensile stress,residual stress and fatigue damage were studied by experiment.The results show that the method can effectively measure the stress state and maximum stress of rod material specimen.The maximum stress can be obtained more exactly by measuring the residual stress.Experimental results show that the detection sensitivity of fatigue damage is lower than that of stress concentration;the detection sensitivity of fatigue damage to low carbon steel Q235 is greater than 45 steel.