E.J. Richards

Fatigue failures occur on aircraft structures both externally and internally, failures occur to electronics, etc., and large noise levels are obtained in cabins, as a result of the large non-periodic pressure fluctuations caused by the mixing of jets with the adjacent air and by the turbulent flow in boundary layers. This introductory paper outlines the essential steps involved in any analysis of the problem; a short synopsis being first given of. the generalised methods being put forward by which r. m. s. stress levels and the expected fatigue life may be predicted from the power spectrum of the disturbance. Recent developments in the analysis of the pressure spectra, both close to jets and in boundary layers, are referred to and are related, as much as possible, to the turbulence field. An introduction is given to the significance of space and time correlation functions of these pressures and recent results of correlation studies are considered briefly, for a variety of engine conditions. Some comments are also made on the possibilities of the reduction of structural excitation by the use of suitable engine positioning and jet nozzle configuration and a reference is made to another type of excitation on narrow delta types of aircraft configuration. The influence of the above excitation is next discussed, first on single panels and more generally on typical aircraft structures. The !arge number of possible modes of oscillation are emphasised and the influence of structural and acoustic damping outlined. Reference is made to recent Southampton experiments on both these topics and also to recent theoretical work on the response of stiffened cylinders to simplified acoustic loading.

WGL-Tagung, Köln, 1960

Conference Paper

englisch

21,0 x 29,7 cm, 12 Seiten

Jahrbuch der Wissenschaftlichen Gesellschaft für Luftfahrt, 1960; S.395-406; 1960; Braunschweig : Vieweg

NA

Bestellbar

1961