These slides were presented at the NAFEMS World Congress 2025, held in Salzburg, Austria from May 19–22, 2025.

Abstract

As the US military extends the service life of aging weapon systems, the need for accurate models of aircraft structures has become critical. The original finite element models (FEMs) used during the development of these legacy systems were either not procured by the military or not maintained, necessitating the development of new FEMs from 2D drawings and scanned parts. Given that many weapon systems were tested up to 60 years ago, the absence of original test data presents significant challenges for model validation. This has led to the United States Air Force performing full scale test for model validation. This presentation delves into Southwest Research Institute recent experiences in performing full-scale validation test for the T-38 and A-10 aircraft finite element models. The full aircraft NASTRAN structural analysis model of the T-38 is being developed by Northrop Grumman. The A-10 aircraft structural analysis model is being developed by the United States Airforce A-10 analysis section with support from Southwest Research Institute. To performing these full-scale validation test, a diverse array of measurement techniques, including deflection potentiometers, strain gages, fiber optic strain sensors, and digital image correlation, were employed. Depending on the component the validation tests often are performed on structure that will be returned to active service. This necessitates extra caution to ensure the structure is not damaged and can limit options for methods to attach to and load the structure. The presentation will discuss the specific test setups, the resulting data, status of the validation effort and key lessons learned from the validation process. In addition to these validation efforts, SwRI will discuss how the validated T-38 finite element analysis model is being used to update the damage tolerance analysis of the -33 wing. This will include stress-to-load equation development, development of stress sequence, damage tolerance analysis to determine crack growth progression and failure.