Impact Behaviour of Aluminium Foam Sandwich Panels with Fibre Metal Laminate Skins

摘要

Aluminium (Al) foam sandwich panels are of strong capability to resist impact and absorb energy since sandwich panels integrate the advantages of both Al foam core and the skin material. Though many researches on Al foam sandwich panels with metal skins or composite skins have been extensively reported, research on Al foam sandwich panels with Fibre Metal Laminate (FML) skins is still very limited. A new type of Al foam sandwich panels with FML skins aiming for excellent impact resistance is developed, fabricated and tested in this thesis. Gas gun impact testing and drop weight impact testing are conducted to study the high velocity impact behaviour and the low velocity impact behaviour of the sandwich panels respectively. The effect of the skin thickness and foam core thickness on the impact resistance and failure of the sandwich panels are studied and reported in this thesis. From the impact tests, the developed sandwich panels exhibit very good impact resistance and energy absorption. It is also found that the increase in skin thickness can greatly improve the impact resistance and energy absorption, while the elevation of energy absorption is very limited from the thickness increase of the foam core.The representative volume element (RVE) method is an effective way of modelling representative unit cell based materials. With proper setting of boundary conditions, one cell can represent the material and the size effect of the model can be neglected. To gain an insightful understanding to the micromechanical behaviour of Al foam, two RVE models based on repeating tetrakaidecahedron cells and octadecahedron cells are developed to model the mechanical behaviour. The numerical results show that the mechanical behaviour of Al foam can be very well modelled using the RVE models. Parametric effect including cell size, porosity and loading rate on the mechanical behaviour is also investigated and reported. A finite element model in LS-DYNA is developed to model the impact response of the developed Al foam sandwich panels with FML skins subjected to high velocity impact. The deformation process and failure modes during impact process are also modelled. The modelling is found agreeing well with test data. The parametric effect of projectile shape and impact angle on the impact behaviour of the Al foam sandwich panels is also studied and stated. Finally, a finite element model is developed to model the low velocity impact behaviour of tested Al foam sandwich panels with FML skins subjected to drop weight impact test. The model is found to be able to model the impact process and failure modes effectively and accurately.