Guidelines for reduction of random modal test data

摘要

Based on the assumption that the test data are stationary random and follows a Gaussian probability distribution, guidelines for choosing the sampling rate, frequency resolution, number of ensemble averages, block size, filter cut-offpoint and total time record to be analyzed are presented. Al so included in the paper are expressions equating frequency resolution to bias error; graphs relating anti-aliasing filter slopes to amplitude attenuation and graphs relating confidencelevels in estimating the true mean square, auto-spectra, and transfer function to the frequency resolution and total time record of test data analyzed.