Fluid-structure interaction mechanism in shear thickening fluid/Foam composite for advanced protective structures

Fluid-structure interaction (FSI) between shear thickening fluid (STF) and soft materials is pivotal in designing advanced protective structures. This study delves into the FSI mechanisms within a composite structure known as STF/Foam, which features the infusion of STF into foam. Through comprehensive drop weight tests, the STF/ Foam exhibited exceptional cushioning performance. In addition to analyzing FSI from the perspective of structural materials, this study also examines it from the STF standpoint, enabling a multi-faceted understanding of the energy absorption mechanism. To accurately characterize the rheological properties of STF, a novel decoupling method is proposed, accounting for both temporal and spatial inhomogeneities of STF. The research findings indicate that the viscosity variation of STF significantly enhances the energy absorption capabilities of the STF/Foam composite. This study reveals the intricate fluid-solid coupling mechanism between STF and foam. The STF demonstrates a unique combination of shear resistance akin to high-viscosity fluids and the easy flow characteristics of low-viscosity fluids. The modulation of STF viscosity optimizes the structural deformation pattern, thereby rationalizing the energy absorption mechanism of the composite. Consequently, STF/Foam showcases superior cushioning performance. Further investigation into various parameters associated with STF and foam highlights their influence on the structural cushioning performance. These insights lay a theoretical foundation and provide design guidelines for the future development of STF-based controllable protective structures.