Material selection framework for lift-based wave energy converters using fuzzy topsis

Material selection is a crucial aspect in the design of reliable, efficient and long-lasting wave energy converters (WECs). However, to this date, the development of material selection methodologies for the structural components of WECs remains vastly unexplored. This paper addresses this research gap for the case of lift-based WECs. Specifically, we focus on the material selection for the hydrofoils of the device. Five different material candidates are considered: offshore steel, high-strength offshore steel, aluminium alloy, carbon and glass fibre reinforced composites. The different materials are evaluated subject to different criteria relevant to WEC design and via a fuzzy TOPSIS approach to account for the novelty of the assessment. The design criteria are structural reliability, hydrodynamic efficiency, offshore maintainability, total manufacturing cost and environmental impact. Three scenarios of the life-cycle of the WEC are considered: conceptual, commercial and future projection stage. Results show that the choice of optimal materials could change from present to future, and that multi-criteria decision making tools aided with a fuzzy approach can help in reducing the probability of mechanical failures and poor selection of materials at different stages of the life-cycle of novel WECs. In particular, the proposed methodology is relevant when certain material selection criteria are difficult to quantify.