Integrated Multi-Criteria Decision-Making for the Selection of Natural and Synthetic Fiber-Reinforced Composites for Unmanned Aerial Vehicle Micro-Turbojet Engine Inlets.

This study develops an integrated Analytic Hierarchy Process (AHP) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) multi-criteria decision-making (MCDM) framework to systematically evaluate and rank composite material combinations based on 24 fibers (16 natural and 8 synthetic), 15 matrices (thermosets, thermoplastics, and biopolymers), and 9 fiber volume fractions (30-70%) for UAV inlet applications. Ten evaluation criteria covering technical performance, environmental sustainability, and economic viability were weighted using AHP pairwise comparisons based on Saaty's 1-9 scale, yielding a consistency ratio of CR = 0.009, which confirms the reliability of the judgments. The TOPSIS analysis identified Carbon (PAN-HM)/Epoxy as the optimal composite material, achieving the highest TOPSIS score of 0.8893. In contrast, Flax/Epoxy emerged as the best natural fiber composite, with a TOPSIS score of 0.2686, indicating a performance gap of approximately 231% in favor of the synthetic composite. Comprehensive sensitivity analysis across four weighting scenarios (Equal, Technical, Environmental, and Economic) confirmed the stability of the reinforcement rankings, with Carbon (PAN-HM) remaining the top synthetic fiber and flax the top natural fiber across all scenarios. The findings contribute to the growing body of knowledge on sustainable aerospace materials and provide practical guidance for UAV designers seeking to optimize material selection for micro-turbojet engine inlet components, supporting the development of more environmentally responsible UAV designs while maintaining the performance requirements for safe and reliable operation.