Enhanced damping of non-metallic structures for resistance to acoustical fatigue and impact damage

You are here: Homepage > Search

Enhanced damping of non-metallic structures for resistance to acoustical fatigue and impact damage

Ely, R.A.

This paper addresses the need to increase damping of resonant vibrations and impact-induced vibrations of plastic and non-metallic composite aircraft structures. The paper provides indications of the conditions under which such structures will suffer acoustical fatigue. Composite and plastic structural components on existing aircraft may be experiencing acoustical fatigue that is mis-diagnosed, and they are likely to fatigue in the future as their parent aircraft accumulate more flight time. The increased performance envelope of future aircraft will cause their composite and plastic components to be more vulnerable than current non-metallic structures to acoustical fatigue. Acoustical excitations of concern are fan noise, jet noise, propfan noise, or fluctuating pressures associated with local separation of a turbulent boundary layer. This paper relates such excitations to mathematical and experimental methods for characterizing the dynamic elastic and damping properties of non-metallic materials. The use of dynamic characterizations of non-metals in predicting and controlling acoustical fatigue of non-metallic aircraft structures is discussed. The importance of including considerations of frequency dependent damping in analyses and measurements of impact-induced vibrations of non-metallic structures is discussed.