磁芯探头涡流检测信号数值模拟方法研究  

A numerical simulation method for ECT of probe with magnetic core

作　　者：石瀚林 王猛[2] 蔡文路[1] 陈洪恩[1] 陈晖[2] 陈振茂[1] SHI Hanlin;WANG Meng;CAI Wenlu;CHEN Hong'en;CHEN Hui;CHEN Zhenmao(Shaanxi ERC of NDT and Structural Integrity/State Key Lab for Strength and Vibration of Mechanical Structures,Xi'an Jiaotong University,710049 Xi'an,China;Xi'an Aerospace Propulsion Institute,710100 Xi'an,China)

机构地区：[1]西安交通大学机械结构强度与振动国家重点实验室,陕西省无损检测与结构完整性评价工程技术中心,西安710049 [2]西安航天动力研究所,西安710100

出　　处：《应用力学学报》2023年第6期1324-1334,共11页Chinese Journal of Applied Mechanics

基　　金：国家重点研发资助项目(No.2022YFB3707202)。

摘　　要：提出了一种基于退磁场理论的磁芯探头涡流检测信号简化数值模拟方法,基于已有FEM-BEM涡流检测数值方法开发了计算程序,通过与商用软件比较验证了其有效性。首先,分析了磁芯磁化过程中内部退磁场的特点,提出了磁芯退磁场和磁化场的计算方法;其次,提出了磁芯线圈激励磁场计算方法,考虑了激励线圈传导电流和磁芯等效磁流,利用磁流环电流模型和毕奥萨法尔定律进行激励磁场计算;最后,采用和激励磁场计算类似的思路进行了检测信号分析,即用感生涡流二次磁场替代激励线圈磁场来计算检测线圈磁芯的退磁场和磁化场,并基于磁芯内部磁通变化计算检测电压信号。基于所提理论,本研究在已有FEM-BEM混合法涡流检测数值模拟软件的基础上,开发了可考虑磁芯影响的涡流检测数值计算程序。对于不同参数条件下的磁芯探头涡流检测问题,本研究方法与全域有限元商用软件计算结果一致,但本研究方法原理更为直观,验证了方法和程序的有效性。A numerical tool to simulate the ECT signals of a probe with magnetic core is indispensable.However,the conventional full domain 3D FEM numerical method is hard to treat the probe scan and the numerical results cannot give clear and direct instruction for the probe design.In this paper,a numerical scheme taking the demagnetization field in the magnetic core into account is proposed to tackle with problems related to the magnetic core,and its feasibility is investigated through comparing with a conventional full domain FEM software.First,the features of the demagnetization field in the magnetic core are discussed,and methods to calculate the demagnetization field and the core magnetization are developed.Second,a simulation method for the excitation magnetic field of a cored ECT probe is proposed.In practice,the excitation magnetic field of the ECT probe with magnetic core is obtained through superposition of the magnetic fields due to the driving current in excitation coil and the equivalent magnetic current in core,while the magnetic current is treated with a solenoidal coil model.Third,a numerical scheme similar to the method for excitation coil is adopted to calculate the output signal of the cored pickup coil.In order to obtain the magnetization perturbation in the core due to eddy current,only the driving magnetic field in the magnetic core is necessary to be replaced by the field due to the eddy current.The pickup signal,then,can be obtained from the magnetic flux variation in pickup coil based on the Faraday's law.Based on the ideas above,the conventional FEM-BEM hybrid code of A-φformulation is updated and the ECT signals due to probes of different magnetic core configurations are calculated.The numerical results are found in good consistence with those of a conventional software of full FEM,which demonstrates the validity of the proposed method and the corresponding numerical codes.

关 键 词：涡流检测 磁芯 数值模拟 FEM-BEM方法 退磁场 

分 类 号：TM154.2[电气工程—电工理论与新技术]