A Study of Guided Ultrasonic Wave Propagation Characteristics in Thin Aluminum Plate for Damage Detection.

摘要

The use of Lamb waves to investigate damage in thin metal plates is investigated. This study is necessary to have a thorough understanding of Lamb wave propagation characteristics, its dispersion phenomena, its behavior when scattered from minor flaws, and its ability to detect damages. Nowadays, there is a growing interest to use Lamb waves for damage detection techniques.;A literature review of Lamb waves and other types of waves pertinent to their use in damage detection mechanisms is presented. Dispersion curves for aluminum plates are studied for symmetric and anti-symmetric modes. Detailed comparison between the different modes, and the merits and demerits of these wave modes which help to select an appropriate mode for use in damage detection is also explained. Different types of damage have been detected experimentally using a pitch-catch method and are verified by using Waveform Revealer and finite element software, Pzflex. Based on selected fundamental Lamb wave modes, damage inflicted by drilling a through-thickness hole in an aluminum plate has been detected experimentally using a pitch-catch method by applying mode conversion phenomena and is verified by using Waveform Revealer. Moreover, different sizes of through-thickness holes and cracks in an aluminum plate have been detected by running simulations in Pzflex and using changes in time of flight and amplitude of the wave as parameters.;Based on the experimental and simulation results, it is concluded in this paper that Lamb waves are sensitive to cracks and holes in thin aluminum plates, and that these types of defects can be detected by techniques using Lamb waves.