NONSTATIONARY MEAN-SQUARE RESPONSE DUE TO UNIFORMLY AMPLITUDE-MODULATED RANDOM EXCITATIONS

The non-stationary random response problem of a time-invariant linear system subjected to uniformly amplitude modulated random excitations i s studied. Based on the time-domain modal analysis of random vibration s, the time-dependent correlation function matrix of the response is o btained in closed form, so that the time-dependent mean square random response is easily obtained without resort to cumbersome integration. The method is straightforward and efficient, since it reduces the comp licated non-stationary random response problem to a solution with comp lex number algebraic operations only. The method is applicable to non- stationary response problems of linear systems, whether they are symme trical ones with classical damping or non-symmetrical ones with non-cl assical damping. Numerical examples of a 3-DOF time-invariant, non-cla ssically damped linear system under modulated white noise or modulated filtered white noise excitations are included. Some remarks on the st ructural properties of the time-dependent correlations functions of th e non-stationary random response, that we consider useful, are put in the Appendix.