Assessment of Fatigue Damage in Solid Plates Using Ultrasonic Lamb Wave Spectra

Changes in the mechanical properties of a solid plate, induced by fatigue damage, will influence the features of ultrasonic Lamb wave propagation such as dispersion, amplitude and attenuation. The feasibility of using ultrasonic Lamb wave spectra to assess fatigue damage in solid plates was briefly discussed. For a given aluminum (2024-T3) sheet, the amplitude-frequency curves before and after cyclic loading were measured with the established experimental setup for ultrasonic Lamb waves. Based on the data measured, the ultrasonic Lamb wave spectra diagrams were established. Clear difference between the two spectra diagrams before and after cyclic loading could be found. It is concluded that ultrasonic Lamb wave spectra may be used to effectively assess the early stages of fatigue damage in solid plates.