An integrated framework for the prediction of Remaining Useful Life (RUL) of supersonic aircraft using experimental strain data

Abstract

This study aims to evaluate Remaining Useful Life (RUL) of supersonic aircraft using a two-fold integrated approach that combines experimental and computational methods. A comprehensive framework was developed that included the identification of Fatigue Critical Locations (FCLs), aircraft instrumentation, Ground Strain Survey (GSS), in-flight testing, and RUL estimation. Internal and external CAD models of the aircraft were developed. CFD analysis on various critical flight maneuvers inside the flight envelope was performed using an external CAD model. Subsequently, Finite Element Analysis (FEA) was carried out under severe CFD load cases. Based on FEA results, five FCLs were identified on the wing, two on the vertical tail, and two on the horizontal stabilizer. In the experimental phase, the aircraft was instrumented with strain gauges, accelerometers, and a Data Acquisition Unit (DAQ) to collect in-flight structural testing data. The FEA model was calibrated through GSS. The calibrated weights were applied to the aircraft wings; corresponding experimental strains were recorded and validated against the FE model, yielding a percentage error of 5%–11%. Five flight tests, carefully selected based on historical aircraft trends and critical aircraft maneuvers, were performed to obtain in-flight strain data. The Palmgren-Miner rule was used to evaluate damage caused by each flight test against each structural member on identified FCLs. The total damage was estimated by extending the assessment over the aircraft’s operational life span, surpassing 3000 OEM-defined flying hours. The Main Spar of the wing was found to have the least life of 7089.52 AFHRs, making it the most critical structural member of the aircraft. This framework provides a systematic methodology for estimating RUL, monitoring structural health, addressing gaps in existing methods for evaluating catastrophic failure, and serving as a valuable source for life extension studies in the aviation sector.