Residual strength of an ARALL laminate containing a crack

The residual tensile strength of a cracked ARALL (ARamid-fibrereinforced-polymer/ALuminium Laminates) sandwich with an aramid-fibre/epoxy ply in the middle and two aluminium alloy plies on the outside is studied in this paper. It is assumed that both a Dugdale strip yielding zone in the aluminium layers and a strip damage zone in the fibre composite layer are developed concurrently at the crack tip. Two important parameters have been identified and these are the maximum separation displacement δ_o of the fibre composite damage zone and the metal deformation parameter J_c/σ_ys, where J_c is the critical J-integral and σ_ys, is the yielding strength of the metal. The requirement that the strength of ARALL is comparable to that of their metal counterpart can be met if δ_o is close to J_c/σ_ys.