Delamination detection in composite laminates using dispersion change based on mode conversion of Lamb waves

Abstract

A new ultrasonic propagation system has been constructed using macrofiber composite (MFC) actuators and fiber Bragg grating (FBG) sensors. The MFCs and FBGs can be integrated into composite laminates because of their small size and high fracture strain. The developed system can send and receive broadband Lamb waves. In this research, this system was used to detect delamination damage in composite laminates. First, the multiple modes of Lamb waves in a carbon-fiber-reinforced plastic (CFRP) quasi-isotropic laminate were identified by transmitting and receiving the symmetric and antisymmetric modes separately. Then, the mode conversions at both tips of a delamination were investigated through an experiment and a two-dimensional finite element analysis (FEA). A new delamination detection method was proposed on the basis of the mode conversions, and experiments were carried out on laminates with an artificial delamination. When antisymmetric modes were excited, the frequency dispersion of the received A 1 mode changed, depending on the delamination length owing to the mode conversion between the A 1 mode and the S 0 mode. This phenomenon was confirmed through the FEA and these results prove that this new method is effective in detecting a delamination in CFRP laminates.

A Damage Model for Adhesively Bonded Single-Lap Thick Composite Joints

“…The damage initiation criteria for the composite adherend are based on Hashin's theory [27,28]. The damage initiation in fiber is indicated by F/ > 1, and the damage initiation in matrix is indicated by E", > 1, where >0 <0 (8) 25V (9) where Ef and E" are damage initiation indicators of fiber and matrix, respectively. X^ and X*-are, respectively, the longitudinal tensile and compressive strength.…”

“…Since the adhesive is sandwiched between composite adherends, its damage, especially inside the laminate, is difficult to observe. Numerous researchers [1][2][3][4][5][6][7][8][9][10] have focused on experimental methods to detect delamination of laminated composite. For example, Kessler et al [3] and Shang et al [9] used Lamb wave methods for delamination identification, whereas Kessler et al [4] used frequency response methods, and Kyriazoglou et al [5] adopted vibration damping to detect crack.…”

Quantitative identification of delamination at different interfaces using guided wave signals in composite laminates

“…have been introduced. Various experimental techniques using different smart actuators such as Piezoelectric transducer (Lead zirconate titanate, PZT), 16,29 macro fiber composite actuators, 30 and air-coupled ultrasonic transducers 14,19 have also been developed to obtain desirable Lamb waves.…”

Non-baseline identification of delamination in plates using wavelet-aided fractal analysis of two-dimensional mode shapes

“…The performance of the system was experimentally validated using a 1.8-mmthick multilayer composite laminate. Okabe et al (2010) constructed an ultrasonic propagation system with macrofiber composite actuators and fiber Bragg grating sensors. This system efficiently identified delamination in composite laminates based on mode conversion of Lamb waves.…”