Ultrasonic Railroad Wheel Inspection Using EMATs (Electromagnetic-Accoustic Transducers), Report No. 18

摘要

The report is number 18 in a series covering the research performed by the National Institute of Standards and Technology (formerly National Bureau of Standards) for the Federal Railroad Administration. The issue collects seven reprints and preprints of papers written by the Fracture and Deformation Division over the last two years on the ultrasonic nondestructive evaluation of railroad wheels for the presence of residual stress and cracks. All the work concentrated on the use of electromagnetic-acoustic transducers (EMATs). Tensile residual stresses and tread cracks are major factors in wheel failure. Two ultrasonic techniques are applicable to these wear defects: (1) Birefringence: A stress field effects the velocity of a shear horizontal wave depending on its polarization. Precise velocity measurements in a wheel rim may allow calculation of the amount and direction of stresses; (2) Pulse-echo: A Rayleigh (surface) wave transducer mounted inside the rail can introduce a signal to interrogate the circumference of a wheel as it rolls by. An echo indicates a flaw's presence and size.