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Generating Guided Waves for Detection of Transverse Type-Defects in Rails

Detection of damage in rails can be achieved by using ultrasonic guided waves. It is practical that these waves can propagate as lengthy as possible along the rail structure. In this work, the generation of adequate guided waves is considered by performing pertinent laser irradiation of the rail head. Special laser spots were applied through out-of-phase masks collocated on both sides of the rail. Simulation of this excitation configuration was performed by means of the finite element method. It was found that the proposed method enables to trigger sufficiently high stress pulses and generate adequate pattern of waves from a lot of other modes that are likely to exist for a common rail. These waves were found to be sensitive to small localized transverse like defects in the rail system.