Case Study Comparative Analysis of Brake Disc Materials Using the WASPAS Method

Selecting materials for vehicle brake discs is a critical engineering decision that directly impacts vehicle safety, braking performance, durability, and cost. Brake discs must efficiently convert kinetic energy into thermal energy while withstanding high temperatures, friction, and mechanical stresses during braking. Key factors influencing material selection include mechanical strength, stiffness, thermal conductivity, wear resistance, friction characteristics, manufacturability, and economic feasibility. Traditionally, cast iron – particularly gray cast iron – has been the most widely used brake disc material due to its excellent heat dissipation, high wear resistance, stable friction behavior, and cost-effectiveness. However, increasing demands for lightweight vehicles, improved fuel efficiency, and enhanced braking performance have driven research into advanced materials such as titanium alloys, aluminum matrix composites (AMCs), metal matrix composites (MMCs), and carbon or ceramic-based composites. These materials offer advantages such as reduced weight, superior thermal stability, and improved fade resistance, although they often involve higher manufacturing costs and production complexity. In this study, the material selection process is carried out using the WASPAS (Weighted Aggregated Sum Product Assessment) method, a multi-criteria decision-making approach that combines weighted sum and weighted product models. Key performance parameters considered include compressive strength, friction properties, specific heat, specific gravity, and wear rate. The materials evaluated include gray cast iron (GCI), Ti-6Al-4V alloy, and composite-based alternatives. The results indicate that gray cast iron achieves the highest overall ranking due to its balanced thermo-mechanical properties and cost-effectiveness, while the Ti-6Al-4V alloy ranks lowest based on the selected criteria. Brake disc material selection is a multi-dimensional optimization problem that requires careful evaluation of performance, safety, and economic factors. While advanced materials hold promise for high-performance applications, gray cast iron remains the most suitable choice for conventional automotive braking systems due to its reliability, affordability, and proven performance