Effect of fibre hybridization on interfacial micro-stress fields using 3D RVEs

Abstract

This study investigates the effect of the degree of fibre-hybridization (i.e., fibre volume fractions) and fibre type (i.e., primary and secondary) in uni-directional composite laminae with intra-laminar hybridisation on lamina elastic constants and micro-stress fields, with an emphasis on interfacial micro-stress, using three-dimensional representative volume elements (3D RVEs). Primary fibres (i.e., S-glass and carbon AS4), fibres with a reinforcing role, and secondary fibre (i.e., polypropylene, PET and PEEK), fibres with a toughening role, have been employed in this study. A micro-mechanical study using six independent loading cases has been conducted to predict the nine engineering constants and specific elastic lamina properties for hybrid and non-hybrid fibre composite laminae. The focus of the study is on interfacial (i.e., de-bonding) and matrix-dominated failure modes, and transverse tension, transverse shear and longitudinal shear loading are investigated. Validation of the model developed and employed in this study has been performed comparing the nine engineering constants predicted using FEA results against experimental data and two firmly established analytical models (i.e., Chamis and Mori-Tanaka). The effect of (a) primary and secondary fibre volume fractions, (b) the thermoplastic fibre diameter, and (c) using different thermoplastic fibres on homogenised properties and the micro-stress fields in uni-directional fibre-hybrid S-glass/secondary/epoxy and carbon/secondary/epoxy laminae are analysed. The findings highlight the importance of intra-laminar fibre hybridization in shaping lamina properties and micro-stress fields. Notably, employing different primary and second fibres alters the matrix and the fibre-matrix interfaces micro-stress fields. The stiffness and fibre volume fractions of the primary and secondary fibres are the major parameters affecting the elastic lamina properties and micro-stress fields. This aspect holds promise as an avenue for further exploration in terms of manipulating damage modes and, consequently, the mechanisms governing energy dissipation.