Lamb Wave Based Experimental and Finite Element Simulation Studies for Damage Detection in an Aluminium and a Composite Plate using Geodesic Algorithm

Abstract

The present research focuses on localizing structural damages in an aluminium and a woven fabric composite laminate. Finite Element (FE) and experimental simulation studies are carried out on specimens of these plates with and without damages, and the response data are collected at various sensor locations. Piezoelectric wafer (PW) transducers are used for actuation and reception of Lamb wave. The group velocity dispersion curves obtained through the experiment and simulation are compared with those obtained analytically to ensure effective actuation and sensing of Lamb wave. A Continuous Wavelet Transform (CWT) is used for receiving the arrival times of the wave reflected from the damages to the sensor locations. After acquiring arrival time data, the geodesic algorithm is employed to locate the damage in the specimens. The geodesic algorithm used is a two-step strategy initially using the Pythagorean Theorem to find the discrete geodesics in the structure, using mesh information and followed by locating the intersections of these geodesics to get the damage locations. Herein, the geodesic algorithm is shown to be effective in detecting several damages in a plate, both experimentally and through FE simulation.

Estimation of remaining useful life of fatigued plate specimens using Lamb wave‐based nonlinearity parameters

“…However, the nonlinear techniques are preferred over the linear ones because of their capability to detect microstructural changes prior to a significant drop in local strength and formation of a macroscopic crack. The conventional linear technology is only proficient for detecting macroscopic damages …”

“…The conventional linear technology is only proficient for detecting macroscopic damages. [3][4][5] In recent years, nonlinear ultrasonic techniques have shown a great potential to monitor accumulation of fatigue and thus fatigue life of a material rather than waiting for macroscopic cracks to form. 2,6 This is possible, because nonlinear features of the ultrasonic waves are sensitive to the microstructural changes associated with dislocations.…”

Analyzing the features of material nonlinearity evaluation in a rectangular aluminum beam using Rayleigh waves: theoretical and experimental study

“…Up to 90% of mechanical failures are caused by fatigue due to weak durability, which results from impurities in the material that ultimately become micro-cracks under loads. Therefore, appraisal of their caliber is essential prior to using them for an uninterrupted service as well as for safety [1][2][3][4][5][6][7][8].…”

“…The fracturing in a material is usually instigated from the surface, which suggests evaluating the degradation of the surface at an early stage for the prevention of fracture [10][11][12][13][14][15][16]. As the fracturing is very small and hardly detected by the linear approach such as measurement of attenuation, time of flight [3,4,10], etc, most of the researchers employ the acoustic nonlinearity parameter to quantify the degradation on the surface of the material [11][12][13][14][15][16].…”

“…With that said, this nondispersive feature of Rayleigh wave provides a greater relaxation in choosing the excitation frequency in contrast to Lamb waves. That is, at any frequency, the Rayleigh wave harmonics will travel at the same phase velocity, which is a prerequisite condition for cumulative effect in the nonlinear analysis [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16].…”