Modal Analysis of Guided Waves in a Bar with Arbitrary Cross-Section

概要

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Guided waves, i.e., ultrasonic wave packets propagating in the longitudinal direction, are a promising technique for rapid long-range nondestructive inspection of bar-like structures such as pipes and rails. Guided wave inspection requires determining guided wave velocities (dispersion curves) and wave structures. A computational technique is available to obtain the dispersion curves and wave structures for structures with complex cross-sections. This study develops a more accurate technique using the mirror relation of guided wave modes and an iteration method for solving the eigenproblem. Experimental studies of a JIS 6-kg rail verify that dispersion curves and wave structures can be obtained with sufficient accuracy for typical out-of-plain vibration modes. Wave structures were obtained by measuring waveforms at several points on the curved surface of the rail with a laser interferometer controlled by robot arms.