An experimental investigation on the adhesive, shear strength, and failure modes of glass fibre reinforced polymer flat‐joggle‐flat composite joints over different bonding techniques

Abstract

AbstractThe utilisation of composite materials, especially glass fibre‐reinforced polymer has significantly developed as a result of design innovations in aircraft applications. Joints are a major issue as they are the weak point of composite construction. In this study, considering a flat‐joggle‐flat joint over the single‐lap‐joint, the effect of different manufacturing techniques on co‐bonding, secondary‐bonding, and co‐curing for flat‐joggle‐flat joints on the shear behaviour and dynamic characteristics were investigated. The results affirmed that flat‐joggle‐flat joints increased the load‐carrying capacity by 110 % compared to single‐lap joint. In continuance, results revealed that co‐cure flat‐joggle‐flat joints enhanced the load by 86.43 % and 20.00 %, along with increased shear strength of 8.9 MPa over co‐bonding and secondary‐bonding. Field emission scanning electron microscopy reveals that destructive failure occurs at joints in co‐bonding and secondary‐bonding due to an increase in stress between the adhesive and the adherend, which can lead to fibre failure and matrix damage. The dynamic characteristics, like fundamental natural frequency, are increased in co‐cure flat‐joggle‐flat joint compared to co‐bonding and secondary‐bonding joints. The investigation reveals that innovative flat‐joggle‐flat joints and suitable manufacturing processes improve the shear strength, and dynamic properties of composite joints.