Research On Mechanical Properties Of Ferromagnetic Material Based On Electromagnetic Acoustic Transducer

With the development of modern industry,ferromagnetic materials are widely used in various fields due to their good performance.Therefore,it is necessary to find suitable non-destructive testing technology to detect the mechanical properties of materials timely and effectively.Because of the detection principle and unique advantages of Electromagnetic Acoustic Transducer,the testing technology can detect the internal microstructure state of the tested ferromagnetic materials by ultrasonic signal.This article mainly studies the detection of mechanical properties of ferromagnetic materials based on EMAT.The main research work of this paper includes:(1)Firstly,the working mechanism of EMAT is studied and the energy conversion process of EMAT based on Lorentz force and magnetostrictive effect is analyzed.Also the physical equations of electromagnetic field,force field and displacement field in the transduction process are derived.The specific analysis of the magnetization mechanism and magnetostrictive effect of ferromagnetic materials provides a theoretical basis for the experimental study of EMAT.(2)An electromagnetic ultrasonic testing system which testing the mechanical properties is designed based on the generation mechanism.In order to improve the energy conversion efficiency of the probe,the related parameters of the probe are designed and simulated.Then,the electromagnetic ultrasonic transmitting module and the receiving module are designed to realize the excitation and reception of electromagnetic ultrasonic waves in the specimen.(3)By the electromagnetic ultrasonic testing system based on magnetostrictive effect,the relationship between the amplitude of the ultrasonic and the magnetic flux density is obtained to reflect the magnetostrictive properties of the testing ferromagnetic materials.We draw the ultrasonic signal amplitude-magnetic flux density curve and extract the feature values in the curve as magnetostrictive characteristic parameters.(4)The mechanical characteristics of the cold-rolled steel plate specimens are experimentally studied,the correlation between the mechanical properties and the magnetostrictive characteristic parameters is analyzed.Also a neural network reflecting the mapping relationship is established and the network is optimized by the particle swarm optimization algorithm.Based on the neural network,a quantitative estimation of the mechanical properties of ferromagnetic materials is achieved.