Adhesive Bonded Joints in Composite-Composite Bonding for Aerospace Applications

Abstract

This thesis specifically addresses the improvement in single lap shear strength of huntsman 5052 adhesive attained by using Nano sized carbon materials as secondary reinforcements in the adhesive. Multi walled carbon Nano tubes (MWCNTs) and Graphene Nano platelets (GNPs) were used as secondary reinforcement in commercially available adhesive. Carbon fiber laminate were produced by Liquid Resin Infusion (LRI) process. The laminates were joined as per the guide lines from ASTM composites hand book volume 21. The testing was limited to single lap shear test for comparison purpose and varying all other variables. Also this configuration is widely used in industry due relative ease of joining composites. The optimum bond line thickness was selected after selection of best surface texture. Then MWCNTs and GNPs were tested for different configurations. An improvement of 10% in single lap shear test was observed using MWCNTs and 21% using GNPs. Hygrothermal conditioning was also performed for different concentrations of MWCNTs, GNPs and neat epoxy. No significant improvement in degradation was observed for the secondary reinforced epoxy systems. However, use of nano materials after certain threshold degrades the strength of epoxy and also make it prone to moisture absorption.