Simulation of acoustic emission in carbon fiber-epoxy matrix composite laminates due to transverse cracking: effect of ply stacking sequence

This work focuses on the numerical simulation of the AE due to transverse cracking in laminate composites. The objective of the work is the experimental characterization and numerical simulation of the influence of the ply thickness and stacking sequence on transverse matrix cracking induced acoustic emission. AE signals induced by transverse matrix cracking are simulated numerically using finite elements (FE) for composite laminates exhibiting different number of plies and stacking sequences. 3D FE models of the specimens are set-up using Abaqus™ Standard. Either [0n/90n/0n] or [90n/0n/90n] (n=1 or 3) composite laminates are modeled, one ply thickness is 0.3 mm. Matrix transverse cracking in 90 deg. inner or outer ply is simulated. The influence of the ply thickness on acoustic emission signals recorded at the crack epicenter is significative only for inner ply transverse cracking, whereas similar signals are obtained for outer ply cracking. The frequency content of signals induced by outer ply transverse cracking does not depend on the ply thickness. Contrary to outer ply cracking, the influence of the ply thickness on inner ply transverse cracking induced signals is significative, especially on the frequency content, and on the frequency centroid only close to the crack (Fig. 1). Outer ply cracking rather exhibits signals with a low frequency content, not depending much on the ply thickness, contrary to inner ply cracking, for which the frequency content is higher and more dependent on the ply thickness. Fig.1: Frequency centroid as a function of distance between the source and the sensor obtained numerically for [0n/90 n/0n] and [90n/0n/90n] stacking sequences (n=1 or 3). Results obtained without sensor effect, with a virtual perfect sensor. EWGAE 35, Ljubljana, Slovenia, 13th – 16th Sep. www.ewg