Experimental and numerical investigation of the interface between epoxy matrix and hemp yarn

In the present work, the adhesion between an impregnated hemp yarn and the epoxy matrix was investigated. The micromechanical tests usually used to characterise the fibre/matrix interface were adapted to the yarn/matrix interface. Single yarn composite specimens with yarn axis at 0° were manufactured and submitted to fragmentation tests to determine the experimental interfacial shear strength (IFSS). Specific single yarn composite specimens with yarn axis at 90° from the loading direction were also tested to track by digital image correlation the strain fields in the yarn, in the resin and at the yarn/matrix interface. A finite element analysis was developed and optimised to simulate the fragmentation process and provides a conservative value of IFSS.