Numerical modelling of the low-velocity impact response of hybrid fibre metal laminates with shear-thickening fluid-impregnated Kevlar composites

Extensive research has been carried out on the impact resistance of Kevlar fabrics impregnated with shear-thickening fluid (STF) through both experimental and numerical approaches. However, up-to-date numerical modelling and experimental validation of hybrid fibre metal laminates (FMLs) incorporating with STF-impregnated Kevlar fabric layers remain limited. In this study, STF-impregnated Kevlar fibre metal laminates, with three stacking sequences of 2/1, 3/2 and 4/3, were prepared and subjected to low-velocity projectile impact, at impact energy levels of 30, 48 and 90 J, respectively. Compared with FMLs without STF-impregnated Kevlar layers (PK-FMLs), the FMLs containing STF-impregnated Kevlar fabric (SK-FMLs), the latter show peak-load increases of 12.5, 9.5 and 14.7 % over the former for the three configurations, respectively. Then, a progressive damage model was established to simulate the impact response of PK-FMLs and SK-FMLs. A user-defined VUMAT subroutine was implemented for simulating stiffness degradation and damage evolution in the composite layers, together with Johnson-Cook model for aluminium layers and cohesive zone modelling for adhesive interfaces. The model developed captures the load-displacement response, deformation and failure modes of the laminates, showing reasonably good agreement with the experimental counterparts. The proposed modelling approach provides efficient macroscopic simulation for evaluating and designing the impact resistance of STF-Kevlar fibre-metal laminates.