Preparation, Characterisation And Micromechanical Modelling Of Resin Transfer Moulded Nonwoven Kenaf Fibre Epoxy Composites

• Main Author: Andre, Ningkan Gaduan
• Format: Thesis
• Language: English
• Published: 2016
• Subjects: T Technology; TA401-492 Materials of engineering and construction. Mechanics of materials
• Online Access: http://eprints.usm.my/45721/1/Preparation%2C%20Characterisation%20And%20Micromechanical%20Modelling%20Of%20Resin%20Transfer%20Moulded%20Nonwoven%20Kenaf%20Fibre%20Epoxy%20Composites.pdf; http://eprints.usm.my/45721/

There has been a rapid growth in the utilisation of natural fibre as reinforcement in composites driven by environmental concerns and the advantages they offer such as high specific strength and moduli, and also are environmentfriendly. In this study, nonwoven kenaf fibre/epoxy (NKFE) composites have been fabricated using resin transfer moulding (RTM). The effect of kenaf fibre (KF) volume fraction (Vf) and needle-punching directions on the mechanical properties of the composites have been investigated. The highest tensile strength and modulus were attained at 0.42 Vf and it was found that the composites exhibit tensile isotropy. Optimum flexural properties and fracture toughness were also achieved at 0.42 Vf. The typical load versus displacement graph and scanning electron microscopy (SEM) images of epoxy and NKFE composites revealed that the improvements in the fracture toughness was due to the energy absorbing events caused by the addition of fibres. This study also addresses the importance of fibre elastic anisotropy in the accurate predictions of composite tensile modulus in which both longitudinal (Ef1) and transverse (Ef2) fibre modulus were identified. KF has proven to be highly anisotropic whereby Ef1 and Ef2 were found to be 26.06 GPa and 2.50 GPa, respectively. Meanwhile, micromechanics analysis by Cox-Krenchel model allows the determination of micromechanical parameters of the composites. The analysis also proved the applicability of the model for NKFE composites as the calculated efficiency factors were comparable to the values from previous literatures. Moreover, the analysis verified that the nonwoven KF consists of randomly-oriented fibres which were responsible for the tensile isotropy. In addition, Vf and testing modes (tensile or flexural) show no significant effect on the composite’s efficiency factors. Lastly, the static stress analysis of spare wheel cover by using finite element analysis (FEA) computer program showed that the highest safety factor (SF) was exhibited by NKFE composites at 0.42 Vf, which also possessed the highest specific strength and modulus.