Influence Analysis of Narrowband Random Sweep Range Setup in Mixed Mode Vibration Test

Abstract

Sweeping narrowband random on broadband random (RoR) is a common vibration test method. However, different vibration controllers have different definitions on a sweep frequency range of narrowband. Some controllers define the sweep range by the central frequency of the narrowband, as well as the others by the left and right boundaries of the narrowband bandwidth, respectively. The difference between these two setups may have significant influence on the response of the test specimen when its natural frequency is adjacent to the sweep range, which may lead to different test results. This paper studies the different responses of a single-degree-of-freedom (SDOF) system with different Q between the two setups when conducting RoR tests. Simulating and experimental results are also presented. The conclusion is that the sweep range setup can result to unneglectable test difference and the test operators should be aware of it when setting up the test profile.