Damage characterisation of fibre metal laminates under interlaminar shear load

Abstract

Transverse composite plies are part of the fibre metal laminate Glare ®4B and were investigated under interlaminar shear load. Double-notched shear (DNS) tests were performed and deformation and damage were in situ observed by Scanning Electron Microscopy (SEM) equipped with a loading apparatus. Interlaminar shear strength as well as shear stress values corresponding to the onset of the fibre/matrix-debonding were determined. Although a cross-ply lay-up within the laminate has been interlaminar shear loaded, damage and failure could only be found within the transverse plies. Over their thickness, fibre/matrix-debonding proved to be pronounced near the ply boundaries of the transverse plies, where exceptionally high shear strains could be found. Nevertheless, single fibre/matrix-debonding phenomena were also observed within the centre area of these transverse plies. Although interlaminar shear strain within latter regions is reduced, single events of fibre/matrix-debonding could be attributed to local high stress concentrations due to the fibre arrangement and to small inter fibre distances.