Research Projects

The proposed work originates from the growing industrial demand for advanced multi-material structures that effectively combine Carbon Fibre Reinforced Polymer (CFRP) with aluminium alloys, especially Al6061, to meet stringent targets for lightweighting, fuel efficiency, and emissions reduction in aerospace, automotive, and defence applications. CFRPs provide excellent strength-to-weight ratios, stiffness, and corrosion resistance, while aluminium alloys contribute ductility, ease of forming, and cost-effectiveness. However, reliable joining of CFRP to aluminum remains a significant challenge due to their significantly different thermal conductivities, coefficients of thermal expansion, and surface chemistry, which can result in weak, brittle, or thermally degraded joints. The scientific hypothesis underpinning this proposal is that precise control of friction stir welding (FSW) parameters, combined with systematic surface activation techniques, and their integration with complementary hybrid joining strategies, will create a synergistic effect, enhancing interfacial bonding mechanisms through a combination of mechanical interlocking, controlled heat input, and improved chemical compatibility at the interface. This should produce joints with superior strength, durability, and resistance to failure under complex loading conditions compared to conventional bonding or mechanical fastening methods. The updated research background shows that while prior work has explored friction stir spot welding or bonding techniques individually, there is a lack of systematic investigation into the bonding mechanisms, interface characterization, and microstructural evolution at the CFRP–aluminum interface when using hybrid FSW-based joining approaches, especially when considering the role of surface activation methods. Existing literature does not sufficiently address how process parameters (e.g., tool rotation speed, plunge depth, welding speed) and surface activation treatments affect polymer flow, fiber integrity, or the formation of interfacial features such as Al–O–C bonds, nor does it provide detailed correlation with the fatigue performance, energy absorption capacity of the joint. The specific aims of this project are: - Objective 1: To develop a hybrid joint combining adhesive bonding and friction stir welding (FSW) and investigate the underlying bonding mechanisms by analyzing thermal cycles and interfacial microstructures. - Objective 2: To develop a hybrid joint using adhesive bonding combined with ultrasonic welding (USW) by varying pressure and weld time, and to assess the resulting interfacial bonding behavior, fatigue performance, and energy absorption capacity. - Objective 3: To evaluate surface activation effects (chemical etching, plasma treatment, mechanical texturing) on specific bonding mechanisms and their contributions to CFRP-Al6061 joint performance. The novelty of this work lies in its integrated approach: it moves beyond isolated process or materials studies to systematically explore the synergistic bonding mechanisms of FSW, surface activation, and hybrid joining strategies, paired with comprehensive microstructural and mechanical characterization of the joint interface—something not yet reported in the literature. The anticipated impact of this research is significant as it is expected to provide the fundamental understanding and optimised joining strategies needed to produce robust, reliable CFRP–aluminium hybrid joints. The project will enable the development of next-generation lightweight structures with improved safety, durability, and performance. This will directly support industrial innovation in the transportation sector, leading to lighter vehicles and aircraft with reduced emissions and improved energy efficiency.