Study of the Absorption Energy of Auxetic Structures with Non-Newtonian Fluids

• DOI: 10.3390/ma18061263
• Publication Date: 2025-03-13T10:53:00Z
• Authors: Daniel Barros; Carlos Mota; João Bessa; Fernando Cunha; Nelson Oliveira; Raul Fangueiro

Ballistic impact protection has been enhanced through the use of advanced materials, such as shear thickening fluids (STFs) and auxetic structures. These materials provide high energy absorption, flexibility, and comfort, offering promising solutions for the development of lightweight and effective personal protective equipment. The combination of STFs and auxetic structures has been shown to optimize impact resistance while maintaining mobility. To validate this, a composite made of an auxetic structure impregnated with a polyurethane and STF mixture was evaluated for energy absorption. The auxetic structure, fabricated using high-tenacity polyester, demonstrated superior energy absorption compared to standard foams. The impregnation of the auxetic structure with 200 and 400 wt% Biresin and STF mixtures significantly enhanced its impact energy absorption capacity up to 76% compared to the auxetic reference. With the addition of the STF at a 25:75 ratio into the biresin matrix, improvements were also verified in the absorption, up to 7%, due to the non-Newtonian behavior of the STF, demonstrating the potential of these composites for low-impact applications.