铁磁材料漏磁信号对拉伸应力的响应研究  

Response of Magnetic Flux Leakage Signal to Tensile Stress in Ferromagnetic Material

作　　者：曾少昔 赵春田 李红梅[1] ZENG Shaoxi;ZHAO Chuntian;LI Hongmei(Failure Mechanics and Engineering Disaster Prevention Key Laboratory of Sichuan Province,Sichuan University,Chengdu 610065)

机构地区：[1]四川大学灾变力学与工程防灾四川省重点实验室,成都610065

出　　处：《机械工程学报》2024年第20期68-76,共9页Journal of Mechanical Engineering

基　　金：四川大学中央高校基本科研业务、四川大学引进人才启动(YJ202091);四川省科技计划(2022JDGD0012)资助项目。

摘　　要：铁磁材料不同初始磁化状态对应力磁测有较大影响,因此需要被克服以提高磁测结果的鲁棒性。通过力磁耦合理论分析,适当地增大外加磁场强度H0能使铁磁材料初始磁化状态稳定且可控;同时,应力致磁化曲线上升段被稳定地约束在远小于一般工作荷载的40MPa以内,其下降段随应力的增大呈现出近乎线性的变化规律。基于此,为明晰铁磁材料漏磁信号对拉伸应力σ_(t)的响应,进行了有多处截面几何宽度突变的Q235低碳钢板试件的单轴拉伸力磁耦合试验。通过有限元应力分析获得了不同荷载作用下试件的应力分布状态,进而分析了外加磁场强度H0和拉伸应力σt对漏磁信号法向分量Hp(z)的影响。研究结果表明:通过局部增强H0,在铁磁试件受检部位形成较为可控且稳定的局部磁通回路,能有效地克服金属磁记忆中铁磁试件初始磁化状态随机且多变、检测信号微弱和信噪比低等问题。引入影响系数φ综合反映σ_(t)对特征参数峰-峰振幅S(z)p-p的关联影响,在0 MPa≤σ_(t)≤168 MPa范围内,随着σt的增大,系数φ最大增加了18.4%。Different initial magnetization states of ferromagnetic materials have large influence on stress magnetic detection,which needs to be overcome,to improve the robustness of the magnetic measurement.Through theoretical analysis of magneto-mechanical coupling,the initial magnetization state of ferromagnetic materials can be stable and controlled by appropriately increasing the external magnetic field strength H0.Furthermore,the rising section of the magnetization curve of ferromagnetic materials can be stably constrained within 40 MPa,which is far less than the general working load,and the falling section of the magnetization curve shows a nearly linear change with the increase of the stress.Based on this,uniaxial tensile magneto-mechanical coupling test of a Q235 low-carbon-steel specimen(with multiple cross-section mutations)was carried out,to clear the response of magnetic flux leakage signal of ferromagnetic material to tensile stressσ_(t).The stress distributions of the specimen under different loads were obtained by finite element analysis,and then the effects of H0 and tensile stressσ_(t)on the normal component Hp(z)of magnetic flux leakage signal were analyzed.The results indicate that by locally enhancing H0,a relatively controllable and stable local magnetic flux loop can be formed at the examined part of the specimen,which can effectively overcome the problems caused by random and variable initial magnetization state,weak detection signal and low signal-to-noise ratio in metal magnetic memory detection.The influence coefficientφwas introduced to represent the correlative influence ofσ_(t)on the characteristic parameter peak-peak amplitude S(z)p-p.Within the range of 0 MPa≤σ_(t)≤168 MPa,the maximum increase inφwas 18.4%with the increase ofσ_(t).

关 键 词：初始磁化状态 外加磁场强度 力磁耦合 有限元分析 漏磁检测 

分 类 号：TH701[机械工程—仪器科学与技术] O348[机械工程—精密仪器及机械]