On the fracture mechanical behaviour of fibre reinforced metal laminates (FRMLs)

Abstract

Fibre reinforced metal laminates (FRMLs) are hybrid composite materials consisting of thin metal sheets adhesively bonded together with fibre reinforced polymer composite layers. This combination results in composite laminates having some unusual fracture mechanical characteristics, which are described and analysed in this paper. Experimental results are obtained for a carbon fibre reinforced aluminium laminate (CARE) on the in-plane mechanical properties, notched and post-impact residual strengths, and the effects of fibre–matrix interfacial bond strength and adhesion between metal and fibre composite layers. Microscopy, C-scan, and chemical removal techniques are used to reveal the inter-layer delamination mechanism and the failure behaviour of CARE. A new analytical model for notched residual strength was developed based on a global equilibrium approach. The residual strengths predicted by this model agree well with experimental data of several FRMLs (e.g., CARE and ARALL) containing either a central crack or a circular hole. The effects of metal layer stiffness, fibre types, and fracture toughness of fibre composite layer on notched residual strength are also investigated. Finally, limitations of the proposed crack growth model are discussed and areas of future research presented.