An integrated framework for aircraft structural aging assessment using MCDM and experimental analysis

Aging aircraft structures are prone to material degradation due to prolonged exposure to cyclic loads and harsh environmental conditions. Traditional evaluation methods often rely on extensive testing, sometimes destructive to assess structural integrity, leading to increased downtime and cost. There is a pressing need for an integrated, non-invasive, and data-driven approach to monitor material health, prioritize inspection, and support maintenance decisions. This study presents a comprehensive framework for assessing aircraft material degradation by integrating Finite Element Analysis (FEA), Non-Destructive Testing (NDT), Destructive Testing (DT), and Multi-Criteria Decision-Making (MCDM) techniques. FEA identified the Wing Front Spar (AA-7075-T6) and Main Spar (30CrMnSiNi2A) as the most critical components due to their high stress concentrations. Optical Emission Spectroscopy (OES) revealed elemental depletion in these alloys, particularly reductions in Chromium (Cr) and Copper (Cu), which are essential for corrosion resistance and mechanical strength. Hardness testing confirmed degradation, with a 7.4% reduction observed in 30CrMnSiNi2A and a 20.8% reduction in 30CrMnSiA.Using the Modified Digital Logic (MDL) method, criteria weights were assigned for MCDM analysis. Integration of the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and Preference Ranking Organization Method for Enrichment Evaluation (PROMETHEE) enabled robust component prioritization. The Wing Front Spar was selected for destructive testing, which revealed localized degradation and a 45–52% reduction in fatigue life under cyclic loading compared to standard values. This work demonstrates a simulation- and sensor-based approach to structural evaluation, enabling predictive maintenance, optimized inspection planning, and service life extension in aerospace systems.