Experimental characterisation of the formability of a thermoplastic fibre metal laminate

This study aims to assess the forming behaviour of thermoplastic fibre metal laminates based on a self-reinforced polypropylene composite and an aluminium alloy. The development of a method for the rapid manufacturing of parts made from fibre metal laminates would facilitate the widespread adoption of these materials in the automotive and renewable energy industries. Metallic parts are most commonly manufactured using the method of stamp forming and research into the application of this method to materials such as fibre metal laminates is gathering interest. In this investigation, specimens of varying geometry were stretched over a hemispherical punch and a noncontact optical measurement system was used to detail the stretch forming and analyse the effect of deformation mode on the formability of the laminate. The results from the experimentation were used to determine a forming limit diagram for the fibre metal laminate and to identify the safe forming limits of the material. In addition, the evolution of strain at two points of interest was observed to determine the deformation mode in each specimen and to determine the state of strain in the region of failure. These results were then compared with the forming of monolithic aluminium specimens. A significant finding of this work was that the FML showed superior formability than aluminium. This was shown primarily through the increased forming window elucidated by the forming limit curve for the FML and the more uniform meridian major strain distribution in the FML compared to the aluminium.