Application of magnetostrictive torsional guided waves in fiber reinforced plastic bolts

Aiming at the problems of low signal-to-noise ratio and inconspicuous echo characteristics of electromagnetic ultrasonic signals, the characteristics of magnetostrictive torsional guided waves are analyzed in this paper.The torsional guided wave non-dispersion is suitable for signal processing, and the energy attenuation is small during propagation.The displacement and power flow characteristics of torsional seeding in fiber reinforced plastic (FRP) bolt are analyzed by ANSYS finite element simulation software.A physical experiment platform is built to stimulate and received magnetostrictive torsional guided waves in FRP bolts, and CEEMD-LMS algorithm is used to filter the collected echo signal.The experimental data verifies the validity of the numerical analyzed results.The results show that the propagation power of the magnetostrictive torsional guided wave in the FRP bolts tends to the surface, and is suitable for the detection of the surface defects of the FRP bolts; the signal to noise ratio of magnetostrictive guided wave signal processed by CEEMD-LMS filtering algorithm is improved; magnetostrictive torsional guided wave technology can identify the length and defect position of FRP bolt with circumferential defect.