Changes in the mechanical properties of a solid plate induced by fatigue damage will influence the features of Lamb wave propagation such as dispersion, attenuation and mode conversion. The feasibility of using the amplitude-frequency characteristics and the stress wave factors of Lamb wave propagation to evaluate fatigue damage of a solid plate has been analyzed in this paper. Wedge transducers located on the surface of a solid plate are used to generate and detect the Lamb wave signals. Based on the Ritec-SNAP ultrasonic measurement system, the experimental setup for evaluating fatigue damage of solid plates using a Lamb wave approach has been established. For several specimens, the relationships between the amplitude-frequency characteristics of Lamb wave propagation and the cyclic numbers of fatigue loading (denoted by N), as well as the ones between the stress wave factors of Lamb waves and N, have been experimentally studied. The experimental results show that the stress wave factors of Lamb waves decrease obviously and monotonously with the increment of cycles of fatigue loading. Based on the relationships between the stress wave factors of Lamb waves and N, it can be concluded that the stress wave factors of Lamb waves may be used to effectively evaluate fatigue damage in solid plates.
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