Investigation of Silica-Based Shear Thickening Fluid in Enhancing Composite Impact Resistance

Laminated composite structures have attracted the interest of the modern industry due to their high performances and reduced weight when compared to traditional structural materials. However, they are very sensitive towards out-of-plane dynamic loading that can generate Barely Visible Impact Damage (BVID) within the structure and cause a drastic detriment of mechanical properties. One solution is proposed to overcome this problem by the hybridisation of the laminate stacking sequence using Shear Thickening Fluids (STFs) for absorption of large fractions of impact energy with a minimal damage generation. This work numerically investigated the impact response of Carbon Fibre Reinforced Polymers (CFRP) when a silica-based STF is embedded within the lamination sequence utilising an innovative Ls-Dyna-based Finite-Element Model (FEM). This was developed using an Arbitrary Lagrangian Element (ALE) approach in a fluid-structure interaction (FSI) analysis and calibrated with an experimental impact campaign to determine the best impact resistance as a function of the STF position along the thickness of the laminate. The results showed an improvement in impact resistance for all the hybrid configurations identifying the optimal STF location in the upper portion of the laminate with a reduction in absorbed energy of 42%, damaged area of 35% alongside an increase in contact force ( 36%) with respect to conventional laminate with same stacking sequence and number of plies. The results showed that STF/CFRP structures can be successfully employed for applications in several advanced sectors including aerospace, automotive and energy (wind blades) representing an important step-up in the development of high-impact resistant hybrid composite structures.