Experimental investigation of the effect of weave type on the mechanical properties of woven hemp fabric/epoxy composites

Natural fiber composites have a growing popularity as alternative materials to petroleum-based plastics and glass fiber reinforced composites due to various economic and environmental reasons. Textile preforms such as woven, knitted, braided, nonwoven, and multiaxial fabrics are commonly used in composite industry due to their high mechanical properties, tailorability, ease of handling during production, and versatility in material design. A range of properties can be obtained by varying the weave pattern and fabric architecture in woven fabric composites. In this study, epoxy composites reinforced with hemp woven fabrics with four different weave types were produced. The weave types chosen were quasi-unidirectional (UD), plain, basket 2/2, and twill 2/2 which are commonly used in the composite industry. Fabric properties such as yarn angle, yarn density, and crimp ratio were determined to evaluate their possible effect on composite properties. Tensile and three-point flexural tests were conducted in order to determine the effect of weave type on the mechanical properties of the resulting composites. It was found that UD composites show the highest tensile strength, tensile modulus, flexural strength, and flexural modulus in the 0° (yarn) direction. Plain weave fabric composites showed the second highest tensile and flexural strength and moduli followed by basket 2/2 weave composites. Composites reinforced with twill 2/2 woven fabrics showed the lowest mechanical properties due to high yarn crimp and yarn angle, less balanced structure, and resulting shear forces involved during various loading conditions.