Finite-Element Analysis of Complex Panel Response to Random Loads.

Abstract : The report describes and demonstrates a computerized analysis method for development of sonic-fatigue-resistant structure. Finite-element matrix methods are used to calculate elastic response of complex structure subjected to random pressure loads with random dependence on both space and time. A cross-power spectral density loading function is developed for laboratory noise sources. The methods are demonstrated by comparing computed random response and fatigue failure location of skin-stringer and honeycomb sandwich panels with multipanel measurements taken in a sonic test laboratory. The comparisons include natural frequencies, normal modes, rms and PSD deflection and stress, and prediction of fatigue failure location. An extension is required to account for nonlinear response in order to realize the full potential of finite element methods when applied to development of sonic fatigue resistant structure. (Author)