Novel auxetic thermoset and thermoplastic composites for energy absorption

Abstract

Auxetic materials are characterized as materials with negative Poisson’s ratio (NPR), i.e. stretching of these materials in longitudinal direction results in widening in the transverse direction. This counterintuitive behaviour provides higher energy absorption capacity and damage resistance. Auxetic composites can be made from conventional materials, using the laminated angle-ply method, in which the layers are stacked in a special sequence resulting in NPR. Accordingly, the use of carbon fibers as reinforcement is more appropriate than kevlar or glass fibers as they combine exceptional mechanical properties and low weight. Indeed, there are several carbon fibers and matrices that make them suitable for a range of end-uses. This research work focuses on investigating the mechanical properties of composites reinforced with unidirectional carbon fibers. For this purpose, the effects of fiber orientations and the influence of resin type on the mechanical properties and Poisson’s ratio have been investigated as regards to the tensile and impact behaviours. Carbon fiber stacked at different angles reinforcing thermoset and thermoplastic polymers were studied.FCT, projeto “Development of Auxetic Fibrous Composite for Personal Protection, ref. POCI-01-0145-FEDER-016893 e PTDC/CTM-POL/5814/201