Prediction of the Angular Response Power Spectral Density of Aircraft Structures.
Final rept. Jan 76-Jun 78,
AIR FORCE FLIGHT DYNAMICS LAB WRIGHT-PATTERSON AFB OHIO
Pagination or Media Count:
The design of airborne electro-optical systems requires the knowledge of angular vibration as well as linear vibration of aircraft structures. Rather than predicting the angular vibration subject to aerodynamic and acoustic excitations, an attempt is made here to relate the angular vibration directly to the linear vibration response. With the Bernoulli-Euler beam used as a theoretical model, a relationship has been derived between the linear and angular vibration power spectral density functions. Based on this relationship together with the angular root-mean-squared vibration amplitude as previously predicted by Lee and Whaley AFFDL-TR-76-56, AF Flight Dynamcs Laboratory, Wright-Patterson AFB, Ohio, it is now possible to predict the angular power spectral density and a length scale associated with the angular measurement technique. Tested on the typical flight test data of RF-4C and F-15 fighters, CH-3E helicopter, and B-52 bomber, the predicted angular power spectral density lies within a or - 0 db band about the measurement. Though crude, such a prediction is useful in the preliminary design stage in that one can quickly estimate the angular vibration environment prior to fabrication. Author