FAILURE ANALYSIS AND MATERIAL DEGRADATION OF REUSABLE LAUNCH VEHICLE STRUCTURES

This project investigates the failure analysis and material degradation mechanisms in reusable launch vehicle (RLV) structures, addressing the challenges posed by extreme thermo-mechanical and environmental loads during multiple mission cycles. Unlike expendable systems, RLVs such as those developed by SpaceX and NASA must endure hypersonic heating, thermal gradients up to 1500°C, cyclic pressurization, vibrations, impacts, and oxidative environments, leading to degradation modes including fatigue cracking, creep, oxidation-induced embrittlement, delamination, and buckling. The study reviews key structural challenges, failure mechanisms, and mitigation strategies, emphasizing the need for advanced materials, predictive modelling, and non-destructive evaluation to ensure safety, reliability, and cost-effectiveness. Through a comprehensive analysis, this work provides insights into enhancing structural durability for sustainable space transportation. 
Two aluminum-based composite material series, designated as Sample A and Sample B, were obtained as representative candidate materials for RLV structural components. Sample A were material used to construct the launch vehicle while sample B were materials extracted from the launch vehicle after flight and recovery. Each series was prepared as five individual specimens, labelled 1 to 5 (i.e. A1-A5 and B1-B5), giving ten specimens in total. 
Four mechanical tests were carried out to comprehensively characterize the specimens against the degradation mechanisms before and after flight.
Flexural (three-point bend) testing to evaluate bending strength and stiffness, relevant to structural panels and fuselage sections under aerodynamic and mechanical bending loads. Hardness testing to evaluate surface resistance to indentation, relevant to resistance against surface damage and as an indirect indicator of wear performance. Impact testing to evaluate the energy absorbed prior to fracture under sudden loading, relevant to shock events such as launch vibration and landing impact. Wear testing to evaluate resistance to surface material loss under sliding contact, relevant to repeated friction and surface exposure across reuse cycles. Together, these four tests were considered to represent all mechanical tests applicable within the scope and equipment available for this study, providing a comprehensive mechanical performance profile for each specimen.