T-50 초음속 고등훈련기 손상허용성능 시험평가

T-50 Full-Scale Airframe Durability Test was conducted for two service lifetimes to verify the structural integrity of the airframe against its projected loads environment. After the completion of second life testing, a comprehensive teardown inspection was planned and conducted to identify and document all discrepancies in the structure, which had been initiated and/or propagated as a result of spectrum loading. From the teardown inspection, several discrepancies were found in wide spread structural components, primarily canopy floor support beam, wing carry through bulkheads, wing spars and ribs, wing lower skins and attach fittings, etc. Fractographic analyses, for the most notable inspection findings, were also performed to correlate test results with damage tolerance crack growth analysis models. From these correlation study, T-50 design practice of the damage tolerable single load path, slow crack growth approach was validated and the analysis methods utilizing a representative crack growth retardation parameter - a representative Willenborg Shut-Off Ratio in this study - were proved to be adequately conservative with a high degree of confidence. Design improvement were accomplished to resolve service life related discrepancies and to ensure structural integrity of production airframe.