On transverse matrix cracking initiation in composite laminates

摘要

This paper reports na experimental work performed to determine the onset of transverse matrix cracking in glass/epoxy laminates, under quasi-static and impact loading. Several experimental techniques were employed to monitor the transverse matrix cracking process: edge replication, acoustic emision and X-ray radiography. Three distinct methods were developed to extract the laminate stress at the onset of transverse matrix cracking, directly from the experimental data: theσ-εmethod, based on the stress-strain curve; theη-σmethod, which relies on the crack density versus stress data; and the N-σ, based on the cumulative acoustic emission events versus stress relationship. All these methods give consistent results and allowed the observation of the stacking sequence effects, as well as the influence of the loading rate, on the laminate stress at the onset of transverse matrix cracking.