Characterizing flax fiber reinforced bio-composites under monotonic and cyclic tensile loading

Abstract

Traditional composites such as glass and carbon fiber reinforced polymers (G- and CFRP) can be effectively approximated to linear-elastic materials with brittle failure in most of the cases. On the contrary, natural fiber-reinforced composites (NFRCs) are characterized by non-linear elasticity, viscous effects, and plastic strains far before failure. The present study presents the results of an extensive experimental campaign aimed to the mechanical characterization of unidirectional flax fiber composites (FFRCs) produced through Light Resin Transfer Molding. The nonlinear phenomena characterizing the stiffness evolution and its relations with damage propagation and accumulated inelastic strain is investigated and analyzed through pure monotonic loading tension, cyclic tension, and repeated progressive loading tests. The analysis of the experimental results concentrates on the evaluation of the evolution of the mechanic response as the inelastic strain is accumulated in the sample. Results highlight the need for a complex material model in order to predict the mechanical behavior of flax-based composites.