裂纹闭合临界状态磁特性表征模型  

Characterization Model of Critical State of Crack Closure Based on Magnetic Property

作　　者：邢海燕[1] 朱孔阳 张钋 刘传 段成凯 刘伟男 刘超 XING Haiyan;ZHU Kongyang;ZHANG Po;LIU Chuan;DUAN Chengkai;LIU Weinan;LIU Chao(School of Mechanical Science and Engineering,Northeast Petroleum University,Daqing,Heilongjiang,163318)

机构地区：[1]东北石油大学机械科学与工程学院,大庆163318

出　　处：《中国机械工程》2023年第4期414-420,共7页China Mechanical Engineering

基　　金：黑龙江省自然科学基金联合引导项目(LH2019A004);国家自然科学基金(11272084)。

摘　　要：针对工程实际中低周疲劳裂纹闭合状态难以判定与表征的问题,研究了基于磁特性参数的裂纹闭合临界状态表征规律及模型。以Q235B钢为实验材料,进行分级加载、卸载实验,采用TSC-5M-32金属磁记忆检测仪采集磁特性参数,研究了裂尖裂尾不同塑性区对磁场的影响,通过对比柔度微分法,确定裂纹闭合临界载荷来分析裂纹闭合临界状态磁特性参数ΔH_(p)变化规律。结果表明:载荷小于裂纹闭合临界点Pop时裂纹闭合,ΔH_(p)出现极小值拐点;载荷等于Pop时处于裂纹闭合临界状态,ΔH_(p)向上剧烈跳变出现转折点;载荷大于Pop时,裂纹完全张开,ΔH_(p)维持在较高的水平上下波动。最后在实验的基础上,建立了基于合成磁特性参数ΔH_(p)的裂纹闭合状态表征模型,验证结果表明,模型加载阶段和卸载阶段的模型预测值与实测值的最大相对误差分别为9.398%和11.549%,为工程实际中判断并表征裂纹闭合状态提供新的思路。Determination and characterization of crack closure under low cycle fatigue loads were difficult in engineering practice.The characterization law and models of critical state of crack closure were studied based on magnetic property parameters.Graded loading and unloading experiments were carried out by using Q235B steel as the experimental materials.The TSC-5M-32 metal magnetic memory detector was used to collect magnetic characteristic parameters.The effects of different plastic zones at the crack tip and the crack tail on the magnetic field were investigated.The changing law of the synthetic magnetic characteristic parameter ΔH_(p)at the critical state of crack closure was analyzed by comparing the critical load of crack closure determined by the flexibility differential method.The results show that the cracks close up when the load is less than Popcritical point,and at the same timeΔH_(p)has a minimum inflection point;the crack is in the closure critical state when the load equals to the Pop,and at the same time ΔH_(p)jumps sharply upward with turning points;the cracks open fully when the load is greater than Pop,and at the same time ΔH_(p)fluctuates around at a higher level.Furthermore,the characterization model of crack closure state was established based on magnetic property parameters.The verification results show that,for the loading and unloading phases,the maximum relative errors between the model predicted values and measured values are 9.398% and 11.549% respectively,which provides a new method to judge and characterize the crack closure states for engineering practice.

关 键 词：裂纹闭合 力磁效应 磁特性参数 表征模型 铁磁性材料 

分 类 号：TG115[金属学及工艺—物理冶金]