Study of translaminar fracture toughness of unidirectional flax/epoxy composite

Abstract

Ever growing applications of flax fiber-reinforced composites (FFRCs) and their suitability for structural uses involve implementing the design and failure criteria for these composites. Translaminar fracture is one of the primary failure modes of unidirectional (UD) fiber-reinforced composites, and measuring it is essential for design purposes and in many material failure studies. However, the translaminar fracture parameters have not been evaluated for UD-FFRCs; thus, there is no data available in the literature. Moreover, conventional test methods for this failure mode are complex, and there is no standard method for measuring this value in compression. In this study, the translaminar fracture behavior of a UD flax/epoxy composite has been examined, and its fracture toughness in tension and compression in the fiber direction are determined following existing standard methods as well as using a methodology developed using infrared thermography. Compact tension specimens were adapted and used for this purpose. A fractographic study is conducted to examine the fracture surfaces and better understand the failure mechanisms. For tensile tests, the results of infrared thermography are in good agreement with those of ASTM E1922 and lie in the range of values obtained for similar composites in the literature.