Comparative Analysis of Adhesive Effectiveness in Kevlar/Aluminum 6061-T6 Hybrid Double-Strap Joints: A Study on Static and Fatigue Strength ^†

This research work experimentally investigates the effectiveness of various adhesives in bonding Kevlar fiber-reinforced polymer with aluminum alloy 6061-T6 in a hybrid double-strap joint. Hybrid double-strap joints were developed using thermosetting epoxy Araldite LY5052 with Aradur H5052 and thermoplastic epoxy polyurethane mixed with tetrahydrofuran. These specimens were prepared using a hand layup method. Both adhesives were used to make eighty samples: forty for thermoplastic epoxy polyurethane with tetrahydrofuran and forty for thermosetting epoxy Araldite LY5052 with Aradur H5052. In order to determine the static strength of joints, tensile tests were conducted using a universal testing machine (UTM) where a tension–tension fatigue test was carried out on 50%, 70%, and 80% of the static load at which the joint failed. In the thermosetting double lap strap joint, the findings of both the elongation and fatigue tests showed an increase in strength throughout both the elongation and fatigue cycles. Thermosetting Kevlar hybrid joints have a high static and fatigue strength. Based on the results, thermosetting hybrid joints using Aradur H5052 and epoxy Araldite LY5052 had a static strength of 20.67 KN, whereas a thermoplastic adhesive joint had a static strength of 11.93 KN. Furthermore, the microscopic failure modes revealed that the mode of failure for the joints was cohesive and mixed-mode failure.