Research On Steel Strand Nondestructive Testing Using Magnetostrictive Ultrasonic Guided Waves

Steel strand has a wide application in engineering.It is easy to appear different degrees of damages in actual using process.It is inevitable for us to make health testing or monitoring of steel strand.Aiming at making health detection to steel strand,a sensor of exciting longitudinal mode guided waves was designed based on magnetostrictive effect,ABAQUS software was carried out on simulating the guided wave's propagation in steel strand.The results were verified through experiments.The detail work is presented as follows:Chapter 1 presents the significance and background of the research,makes a comparison between the magnetostrictive guided wave technology and the traditional nondestructive testing technology,introduces the latest domestic and international research status of the steel strand which uses magnetostrictive guided wave testing technology.Chapter 2 introduces the basic concept of guided wave,including the magnetostrictive effect,the phase velocity and group velocity,the dispersion and attenuation of guided waves,the cross section of steel strand was meshed using the numerical method.Based on the semi-analytical finite element method,dispersion curves were calculated by matlab simulation and wave structure was also analyzed.The research above provides a theoretical basis for the sensor design and guided wave testing study subsequently.Chapter 3 designs a sensor which can be used in exciting longitudinal mode's guided waves by making an analysis of the conditions to produce guided wave in steel strand.And a finite element analysis was carried on to simulating the magnetic field of this structure.Chapter 4 studied the propagation characteristics of guided wave by numerical simulation using ABAQUS software in steel strand.Defects of different lengths in steel strand were simulated.Making a contrast on the ability in detecting different steel strands while using guided waves.Chapter 5 builds a magnetostrictive guided wave's detection system,studies the effect in steel strand detection by experiment,validates the effectiveness of the magnetic field's adjustment,compares the detection signals of the array type bias,studies the feasibility of guided wave's detection in steel strand defects,and gets the conclusions respectively.Chapter 6 summarizes the main work of the thesis,lists the conclusion and prospect for further research.