A study of the mechanical properties and scaling effects in a thermoplastic fibre-metal laminate

This study investigates scaling effects in a novel fibre-metal laminate (FML) system based on a thermoplastic matrix. The material is based on an aluminium alloy, a selfreinforced polypropylene composite and a polypropylene film acting as an interlayer adhesive. Initially, the mechanical characterisation of the FMLs and 'their constituents are characterised in tension, flexure and under impact loading. Additionally, the level of adhesion between the composite and aluminium constituents is characterised using fracture mechanics procedures. The performance of the FML is investigated aI!d compared to that offered by its constituents, enabling the advantages of these novel hybrid systems to be highlighted. Two different laminate constructions are employed here, these being an [AI, 0°/90°]5 FML and an [AI, +/- 45°]5 FML. Pronounced differences were observed between the two laminates, with the strain to failure of the latter being approximately 50% greater than the former. Interestingly, flexural tests revealed that the fibre orientation did not affect either the maximum stress or the strain at failure of the FML. Abstract ABSTRACT J. G. Carrillo The second part of the study focuses on investigating scaling effects in this FML system. Here, scale model tests are used to predict the full-scale behaviour of fibremetal laminates. Two laminates are investigated in this part of the research programme, these being [Aln, 00/900 n]5 and [Aln, +/- 45°n]5 with n = '14, Y2, % and 1. Tensile tests are undertaken on laminates prepared using three different scaling approaches, these being ID (scaling the thickness dimension), 2D (scaling the inplane dimensions) and 3D scaling, where all of the dimensions are scaled appropriately. Here, a small decrease in the value of these parameters was observed with increasing specimen size, suggesting that modest scaling effects do exist. Additionally, flexural tests are carried out using a 3D scaling approach, giving a direct comparison with the results generated in tension. The final part of this section investigates scaling effects in the low velocity impact response of the FMLs. Here, it is shown that the impact energy to initiate fracture in the FMLs does not exhibit any size dependency. Other test parameters, such as the impact duration are shown to obey the scaling law, with less than ten percent deviation from the normalised data being observed.EThOS - Electronic Theses Online ServiceGBUnited Kingdo