Modelling and Simulation of Natural Fibre/Epoxy Composites - Prediction of Stress State and Deformations

Natural fibres usually include hemp, jute, and flax fibres are gaining importance in composites with an increasing potential to replace synthetic fibres in advanced composites. Current glass and carbon fibre systems require large amount of energy in production, which has led to an upsurge in interest in the reinforcement potential of natural fibres. To improve composite performance, designers try different possibilities i.e. vary material thickness (lamina), fibre volume fraction, fibre weight ratio, fibre orientation, and fibre layups. Especially with natural fibres, higher variability of mechanical properties is a major challenge due to fibre parameters such as lignin content, pectin content and degree of polymerisation. Therefore, prediction of laminate performance at early stages of design requires computation.

The present work is intended to understand how the flax fibre layups and orientation affect the mechanical behaviour of layered laminated composites. Unidirectional [0]4S, cross-ply [0/90]2S, angle-ply [+45/-45]2S, and quasi-isotropic [0/90/45/-45]S laminates made up of flax fibre reinforced epoxy composites are considered to study tensile, flexural behaviour, and stress distribution in the individual laminae. A classical laminate plate theory (CLPT), which considers the elastic behaviour of the laminae, and a numerical simulation method based on finite element modelling (FEM) are used to predict the stress–strain response of a layered composite. Further, the analytical results and the numerical predictions show that the quasi-isotropic flax/epoxy laminate perform better than angle-ply and cross ply laminates.