Add-On Damping Treatment for Life Extension of the F-15 Upper-Outer Wing Skin
Abstract
The purpose of this investigation was to design, fabricate, and verify candidate add-on damping treatments for the F-15 upper-outer wing skin. The F-15 upper-outer wing skin has experienced high cycle fatigue cracks caused by flow separation on the upper wing surface. The separated flow results during high load factor maneuvers, and in turn induced large vibratory loads on the upper wing skin and associated substructure. The capability of the F-15 to sustain these maneuvers allows the excitation to occur for sufficiently long periods of time to result in damage. Damage accumulates due to the resonant vibration of local skin/stiffener modes. The cracks initiate at the fastener holes adjacent to the integrally machined 'T' stiffeners and tend to propagate parallel to the stiffeners. Two damping treatments resulted from the investigation and were recommended for f-15 fleet retrofit. One was an external constrained-layer treatment and the other was an internal 'stand-off' treatment. Laboratory vibration, corrosion, and thermal aging tests were conducted as part of the development of the add-on damping treatments. Estimates of the life extension factors for the external and internal damping treatments were 5 and 34 respectively.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 30, 1991
- Accession Number
- ADA246149
Entities
People
- Arnel Pacia
- Lynn Rogers
- Michael Parin
- Vincent Levraea
Organizations
- Wright Laboratory