ACOUSTICALLY INDUCED FATIGUE - CAUSE, SOLUTION AND DESIGN ANALYSIS 600294

Since acoustically induced fatigue has become such a widespread problem, all information that assists in the overall solution of the problem is desirable. This paper presents the fatigue problem that developed in the empennage area of the Navy A3D aircraft, presents the details of ground and flight test programs that were undertaken, and presents the test results. One effective solution to the cracking problem was found. It was the addition of an elastomer at the point where cracks occurred. Specimen tests plus flight test data prove that an increased life was obtained. Also the need of silencers for ground run up was established. Finally there is presented a procedure whereby test results may be incorporated with analytical analysis to produce a set of design curves that can be used for design analysis. The design curves do not cover all possible configurations or materials but are intended to serve as a guide for such curves.