Abstract
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.
Highlights
Over the last decades, several industrial sectors including automotive [1], aerospace [2] and energy [3, 4] have focused their attention on composite materials, which improve the general performance of structures due to their high in-plane mechanical properties and low weight [5]
The results for reference and STF configurations (STF_T) samples obtained during the experimental campaign are reported in Fig. 7 and compared with the relative numerical results to demonstrate the ability of the simulations to predict the impact response of the Shear Thickening Fluids (STFs)
STF/Carbon Fibre Reinforced Polymers (CFRP) hybrid samples and traditional CFRP plates with different levels of impact energy (20 and 40 J) were experimentally investigated and results used to validate the numerical model in order to be effective in predicting impact behaviour of STF/CFRP material
Summary
Several industrial sectors including automotive [1], aerospace [2] and energy [3, 4] have focused their attention on composite materials, which improve the general performance of structures due to their high in-plane mechanical properties and low weight [5]. Testing the structure under dynamic loading, relevant results were found as the presence of STF was able to use part of the applied stress on the structure to activate the shearthickening effect increasing the viscosity and, the damping ability of structure Another example of impact resistance improvement is reported by Wang et al, [24] who studied the impact response of a sandwich structure in which shear-thickening fluid was used as core (contained within a frame) for an aluminium sandwich. [31] developed a numerical model to describe the STF-impregnated Kevlar fabric behaviour under ballistic impact analysing the fundamental mechanisms of STFKevlar interaction and its damage suppression nature Another example in simulating STF/ fabric systems using the frictional approach is illustrated by Gürgen [32] that compared the effect of single phase and double phase STF in reinforcing textile subjected to high velocity impact conditions reporting good correlation between numerical and experimental data especially when two typologies of particles are used to create the STF. Once the shear rate is removed, the jamming is removed and the stability of solution (initial viscosity) is restored
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