Influence of additive damping on resonance fatigue of structures

In this paper, progress made at the Air Force Materials Laboratory toward the development of materials and techniques for the control of resonance fatigue in aerospace structures under severe environmental conditions is described. The areas discussed include a simple multi-modal analysis of random response under acoustic excitation incorporating comparisons with experimental data; damping properties of structural metals; high damping metals; plastics and elastomers; tuned damping devices and layered damping techniques incorporating a simple generalization of the classical equations of Oberst to account for free layer treatment behavior in stiffened structures. Finally, examples are given of the manner in which damping has been used to solve practical vibration control problems in the United States Air Force under operational conditions.