Abstract
This paper presents a feasibility study on locating through-width delaminations in fiber-reinforced plastic beams using Lamb waves. An active diagnostic system, consisting of a surface-mounted piezoelectric patch and a vibration sensor, is proposed. The fundamental anti-symmetric Lamb wave mode is chosen as the diagnostic wave. It is generated by applying to the patch an excitation voltage in the form of sinusoidal bursts. Experiments are performed to reveal the wave propagation in clampedfree Kevlar/epoxy beams. The results are used to verify the accuracy of a finite element (FE) model. The FE model is then applied to locate delaminations in some artificial beams. By performing Wavelet Transform (WT) on the predicted acceleration traces, the propagating Lamb waves can be extracted. Based on the arrival times of the extracted waves, delaminations are located with satisfaction. Improve-ment on the damage localization process is possible by eliminating the boundary reflections as well as a priori knowledge on both the size and depth of the delamination.
