A guided wave approach to defect detection under shelling in rail

Rail defects are responsible for many railroad accidents. Trains are derailed and serious consequences often occur. Traditional bulk wave testing wheel probes are often inadequate for finding all defects in a rail, especially under shelling. Shelling takes place as a result of wheel to rail Hertzian contact stresses that lead to surface and subsurface defects, as a result of high stresses below the surface of the rail. Guided waves can detect shelling, if so desired, by employing the proper mode and frequency. Guided waves can also detect transverse cracking under shelling by selecting a mode and frequency insensitive to the shelling, but sensitive to transverse cracking under the shelling. Special modes and frequencies can also be used to detect defects in the web or base of a rail. The guided wave methodology of using a hybrid analytical-FEM technique to accomplish the sensor design and subsequent scattering analysis is presented in this paper. Sensor design to generate rail boundary conditions via dispersion curve and wave structure analysis is illustrated along with a few static shots of animations of wave propagation and reflection from defects in a rail.