Detection Of Ultrasonic Guided Wave Rail Defects

Rail transport, especially the rapid development of high-speed railway line now,has become the most representative of China’s transportation industry, there havebeen many new non-destructive testing technique is widely used in the search for raildefects above. Real-time monitoring system for non-destructive testing of rail defectssustainability and safe and stable operations of railway transportation industry is veryimportant. Ultrasonic guided wave propagation in a solid structure, constantinteraction and structural boundaries, and accompanied by superposition andinterference mode conversion between longitudinal and shear waves and otherphenomena, also resulted in ultrasonic guided waves in elastic media structureusually appears Diversity propagation mode. Ultrasonic guided wave propagationwaveguide medium, the vast majority have spread modal frequency dispersioncharacteristics, rail as a very good sound conduction properties of the solidwaveguide elastic medium, the dispersion can use technical analysis in ultrasonicguided wave rail characteristics to achieve the status of detection of stress and railtrack and that sort of break.First introduced ultrasonic guided wave is mainly research and analysis ofultrasonic guided wave nondestructive testing technology features four modes, modalchoice, modal control and modal decomposition section. From the theoretical levelalso describes the use of semi-analytical finite element method can be calculatedisotropic homogeneous dispersion characteristic curve of free and flexible structure ofultrasonic guided waves. The basic principles of the finite element method, and thebasic steps for problems of different physical and mathematical models, but also onthe finite element method for solving mathematical modeling calculations made somebrief.Then introduced the ultrasonic guided wave nondestructive testing technology andgeneral situation detection process. Then according to the equations of motion of theelastic wave propagation in elastic media structure, strain-displacement relations andstress-strain relationship equations to calculate the ultrasonic wave propagation in an infinite anisotropic elastic medium structure. Also introduced a number of equationsexpressing the structure of the elastic medium stiffness matrix. Finally, a simplecalculation introduced ultrasonic guided waves in isotropic plates dispersion equation,also describes the dispersion curves and guided wave structures ultrasonic guidedwave propagation in plates.Then presents a general method, semi-analytical finite element method to derivethe elastic structure propagation model in any section of the media in generalultrasonic guided waves. From the past made the semi-analytical finite elementmethod models derived in the presence of viscoelastic damping structure, thecalculation speed curve and solving the energy decay curve.Finally, the finite element method for ultrasonic guided wave propagation in railmodal analyzes, ANSYS analysis of the transient dynamics of the basic theory arebriefly described. First, the structure of the flat elastic medium is modeled by usingthe finite element method, and then extended to the rail ultrasonic guided wavepropagation modal finite element modeling study.