Secondary aircraft structures can resonate as a result of very high intensity pressure waves caused by engine and/or aerodynamic effects. This type of excitation can result in acoustically-induced cracking, also known as resonant high-cycle, acoustic or sonic fatigue. In modern military aircraft, high sound pressure level are quite often encountered. For example overall sound pressure levels of the order of 170 db have been recorded. Currently acoustic fatigue cracking has been encountered in the lower external skin of the nacelle of the F/A 18. Efforts to repair these acoustically-induced cracks with standard boron/epoxy patches have not been successful. This paper addresses the repair and life enhancement of these acoustically-induced cracks. The paper investigates the use of constrained layer damping in order to alleviate such cracking. Experimental studies have shown that the use of constrained layered damping alone can be extremely successful in alleviating such cracking. However, if a reinforcement is required to restore the stiffness of the cracked structure, then this may reduce sthe effectiveness of the damping treatment.
Add-on dampers for life enhancement of structural components subjected to acoustic fatigue
Zusatzdämpfer für die funktionelle Verbesserung der Festigkeit struktureller Komponente gegenüber akustischer Ermüdung
1998
7 Seiten, 3 Tabellen, 6 Quellen
Aufsatz (Konferenz)
Englisch
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