Development of expanded cork-STF composites for low-energy impacts mitigation

• Autor(a) principal: Oliveira, Lídia Rafaela Sobral de
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/40909
• topic: Expanded cork; Shear thickening fluid; Composites; Impact; Energy absorption; Eco-friendly

Cork is a natural cellular material, fully sustainable and recyclable, that presents excellent properties for applications concerning impact resistance, with many well-known characteristics in terms of insulation and crashworthiness properties. Shear thickening fluid is a very interesting and promising material in several application fields where a different mechanical behaviour is demanded based on loading rates, like body armour and vibration insulators. The aim of this work is to develop a composite structure using a combination of expanded cork and shear thickening fluids to mitigate low-energy impacts. To achieve this, several shear thickening fluids were developed, with different continuous phase and different solid phase concentrations. Of these, the one that proved to have the best behaviour was chosen to proceed this study. The expanded cork samples were then impregnated with this fluid, using external actions such as ultrasound and vacuum to improve the process. After these samples were subjected to impact, it was concluded that the samples with the best results had been subjected to an ultrasonic bath. In addition to this solution, the agglomeration of expanded cork grains impregnated with shear thickening fluid was also tested. It was concluded that the samples that showed the best impact results were those that had been in the oven, showing better adhesion between grains.