Some aspects of using measured data as the basis of a multi-exciter vibration test

Abstract

With the unrestricted release of MIL-STD-810G, which includes Method 527 - Multi-Exciter Testing, there is more interest than ever in performing vibration tests, which involve using more than one shaker. Also, in the tradition of earlier releases of MIL-STD-810, the use of actual measured (field) data is encouraged wherever possible. While it is acknowledged that Tailoring of the measured data will most probably be required and a Modal survey of the proposed test setup is desirable, many of the steps required to use field data have not been fully reported. This paper will examine some of the detailed requirements for using measured data to perform a multi-exciter random vibration test in the laboratory. Using MIL-STD-810G and IEST committee DTE-022 as background, measurements that can be transformed into a 4-shaker test will be used as an example. While both Time Waveform Replication and Random multi-shaker tests can be established from measured field data, this paper will concentrate on the methodology associated with such Random tests. Using power and cross-spectral densities, from measured field data, the entire system Spectral Density Matrix is filled, to completely define the field vibration environment. Test results will be compared with field measurements and suggestions will be made as to the potential recommended steps needed to assure a successful field simulation. ©2010 Society for Experimental Mechanics Inc.