Identification of delamination position in cross-ply laminated composite beams using S0 Lamb mode

Abstract

In this work, a Lamb wave based technique has been developed for delamination detection in cross-ply laminated beams. By measuring the propagation speed of S 0 Lamb mode and the traveling time of a signal reflected from a delamination site, the location of the delamination can be identified. It has been also confirmed by the experiment that the location of a delamination can be accurately determined by only using the data collected from the sensors in a defect-containing beam, without referring to the baseline signals. Finally, to gain a better understanding of the complex interaction between a Lamb wave and a long delamination, numerical simulations have been carried out using finite element method (FEM). The signal modes generated at the boundaries of the delamination have been analyzed.

Damage Sensing in Blades

“…This wave mechanism is called mode conversion and it also occurs when the wave reaches the edge of a plate, so new wave modes are created and reflected backwards. Mode conversion in delaminations has been studied in several investigations in order to take advantage of these changes and use them to detect and locate these defects (Su et al 2007;Hu et al 2008;Ramadas et al 2009). Hu et al (2008) analysed numerically the propagation of the S 0 mode through a delamination.…”

“…Mode conversion in delaminations has been studied in several investigations in order to take advantage of these changes and use them to detect and locate these defects (Su et al 2007;Hu et al 2008;Ramadas et al 2009). Hu et al (2008) analysed numerically the propagation of the S 0 mode through a delamination. When the S 0 mode enters in the delamination, a small amount of the energy of S 0 (almost undetectable) is reflected backwards and most of it is transmitted forward, but also mode conversion is produced, so a new A 0 mode is reflected and a new A 0 mode is transmitted.…”

“…The wave modes will be affected by the delamination in different ways depending on its mode of vibration. In the literature (Grondel et al 2002;Su et al 2007;Hu et al 2008;Ramadas et al 2009;Rekatsinas et al 2015), the three fundamental wave modes S 0 , A 0 and SH 0 are the most studied and the most commonly used in order to interrogate a structure. The symmetric mode is chosen at low frequencies, below 200 kHz, because they are less dispersive so the shape of the pulse does not spread along the propagation direction which eases the post-analysis and reduce the complexity of the acquired signals.…”

Design, development and testing of multi-functional non-linear ultrasonic instrumentation for the detection of defects and damage in CFRP materials and structures

“…Various non-destructive testing (NDT) methods, such as electrical, X-ray imaging and tomography, thermography, acoustic emission and ultrasonic inspection, have therefore been developed for the detection of defects in CFRP materials, components and structures [1][2][3][4][5][6][7][8][9][10]. Of these, ultrasonic NDT is probably the most widespread, with linear ultrasonic C-scan imaging and Lamb-wave measurement techniques being the most well-known [8,[11][12][13][14]. These well-established linear acoustic methods rely on the measurement of the reverberation, reflection, scattering, transmission or absorption of acoustic energy.…”

Identification of Delamination in Anisotropic Laminated Plate

“…The triangulation technique by several sensors was developed according to the difference in arrival times of A 0 mode wave from the vibration source [2]. With S 0 mode, Hu et al identified the delamination position in cross-ply laminated composite beams [3].…”