A study on interlaminar behavior of carbon/epoxy laminated curved beams by use of acoustic emission

Abstract

The interlaminar tensile strength of carbon/epoxy laminated curved beams with variable thickness and through-the-thickness tufted reinforcement is studied experimentally by means of a four-point-bending test in accordance with ASTM D6415. These tests are monitored by means of the Acoustic Emission (AE) technique in order to gain deeper knowledge of the delamination onset and post-failure behavior. The results show that AE technique has proven to perform well when identifying delamination initiation and evolution after failure. In addition to this, AE has proven to be an appropriate tool to assess the manufacturing quality of the curved-beam, once a previous pattern has been established.

The influence of thickness and recycled milled glass fiber fillers on the delamination resistance of polymer composite angle brackets

“…The low to medium amplitude of AE signals (between 45 and 65 dB) with a low peak frequency range of 10–70 kHz indicated matrix cracking in zone‐I. The dominant failure mode of delamination was initiated and propagated in zone‐II which can be represented by a medium to high amplitude of AE signals (66–99 dB) with a medium peak frequency range of 80–120 kHz 17,39 . Moreover, the fiber failure was observed in zone‐III which shows the medium to high amplitude of AE signals (66–99 dB) with a high peak frequency range of 130–260 kHz.…”

“…However, the interlaminar tensile strength (ILTS) of curved CFRP composites was improved by the tufting technique. 17,23 Komarov et al 24 used aramid filament to stitch a curved CFRP composite and incorporated the carbon short fiber at the interface to improve interlaminar properties. Moreover, Gumgol et al 25 experimentally determined the CBS of L bend unidirectional GFRP composites along with the addition of kenaf short fiber and graphene oxide at the curvature of the L shape specimen.…”

“…The delamination onset and progression in the different thicknesses and stacking sequences of L shape CFRP composites were studied using AE cumulative energy 9,14 . Ranz et al 17 used AE amplitude and energy to identify the onset and propagation of delamination in L shape CFRP composites. Furthermore, the damage mechanisms in L shape GFRP composites were characterized using AE amplitude, duration and rise time 16 .…”

“…They reported that the smaller pin diameter increases the CBS. However, the interlaminar tensile strength (ILTS) of curved CFRP composites was improved by the tufting technique 17,23 . Komarov et al 24 used aramid filament to stitch a curved CFRP composite and incorporated the carbon short fiber at the interface to improve interlaminar properties.…”

“…The low to medium amplitude of AE signals (between 45 and 65 dB) with a low peak frequency range of 10-70 kHz indicated matrix cracking in zone-I. The dominant failure mode of delamination was initiated and propagated in zone-II which can be represented by a medium to high amplitude of AE signals (66-99 dB) with a medium peak frequency range of 80-120 kHz 17,39. F I G U R E 4 Representation of acoustic emission (AE) activity to detect the failure modes in glass/epoxy composite angle brackets (A) 16 layers, (B) 24 layers, and (C) 32 layers.…”