F-111 Stiffener Run Out #2 Parametric Study
DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION MELBOURNE (AUSTRALIA)
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The Royal Australian Air Force RAAF currently has in service a fleet of F-111 aircraft. The conditions under which the RAAF operates these aircraft have proved to be conducive to cracking in the structurally critical wing pivot fitting, and certification testing in the cold proof load test has demonstrated failures at that location. The RAAF has contracted Lockheed Martin Tactical Aircraft Systems LMTAS to perform a Durability And Damage Tolerance Analysis on the aircraft. One control point of concern, in this report, is the Stiffener Run Out Number 2 in the wing pivot fitting. The Aeronautical and Maritime Research Laboratory AMRL developed a bonded boronepoxy reinforcement to reduce the high plastic strains in this critical region, and as a result has significant experience in analysing this region. LMTAS, in conjunction with the RAAF, requested that the AMRL perform an elastic and plastic stress analysis of Stiffener Run Out Number 2 including the effect of varying the geometric parameters associated with it.