Abstract: In light of multi-layer composite materials, random response analysis was achieved with the broadband noise of 168 dB according to GJB150.17A-2009, and frequency response curves were obtained at the position of maximum stress. Based on the analysis results with the broadband noise, two narrowbands were chosen for random response analyses and fatigue life analyses. Experimental results show that fatigue life under the narrowband loading is longer, number of peaks per unit time under the broadband loading is more. When sound pressure spectrum level under narrowband loading increases 0.5 dB, fatigue life under the narrowband loading and the broadband loading is almost equal. Experiments were completed with broadband and narrowband noises at the assistance of traveling wave tubes. Experimental results show that narrowband loading is equivalent to that of the broadband with the selection of appropriate loading bandwidth according to the broadband response results.

Key words: high-level, noises, equivalent loading, broadband, narrowband