AEROELASTIC RESPONSE OF AN AIRCRAFT WING TO RANDOM LOADS.

A method for the prediction of the response of an elastic wing to random loads at flight conditions using rigid model wind tunnel pressure fluctuation measurements is presented. The wing is divided into panels or elements, and the load is computed from measured pressure fluctuations at the center of each panel. A series representation with terms of the correlated noise type is used to curve fit the experimentally determined pressure power spectra. Two methods are used to calculate the random load spectrum: a constant correlation approximation, and an exponential spatially decaying cross-power spectrum model for the pressure. The acceleration and displacement response spectra have been computed for the F-4E aircraft for various Mach numbers, dynamic pressures and flight altitudes. The importance of the unsteady aerodynamic loads induced by the vibration of the wing and input load representation is illustrated by comparing the theoretical predictions with results from flight tests.