Multilayered cork-STF composite structures for impact mitigation

Petroleum-based materials such as expanded polystyrene are widely used in protective equipment. Cork and its composites have shown great potential to be employed in protective equipment, damping, and crashworthy systems. Their sustainability is far more positive than currently used solutions, being characterized by relatively lower carbon footprints. In addition, recent advances in the development of cork composites with shear thickening fluids have demonstrated interesting results for impact mitigation. With this said, a possible solution is being developed using cork and shear thickening fluids. Shear thickening fluids have distinctive non-Newtonian characteristics, especially their capacity to increase viscosity and stiffness under impact circumstances. This study investigates disruptive configurations of cork-based multilayer structures, strategically enhanced with a shear thickening fluid. Samples were subjected to low-energy impact tests with a hemispherical impactor. Some of the explored configurations substantially reduced the impact force, benefiting from the STF incorporation between cork layers. During the impact, it can be seen that the presence of STF slows down the increasing rate of the force during a significant displacement period. It has also been concluded that fabrics impregnated with STF can help achieve better results.