Spectral/critical speed characteristics of structure subject to moving loads

Through the use of a family of generalized Rayleigh quotients, this paper considers the influence of nonstationary time dependent loads/disturbances on the spectral characteristics of structure modeled by 3-D nonpolar elasticity theory wherein the fields are treated as small excursions superposed on large. To generalize the results, the influence of nonconservatism and generalized inertia fields are admitted. The main emphasis of the work is given to determining the various properties of the eigevalue problem arising out of such nonstationary loading situations. This includes ascertaining the occurrence of various types of spectral/critical speed shifts /bifurcations induced by moving disturbances. As a further extension of the work, the results are specialized to the eignevalue problem arising from nonconservative gyroscopic FE simulations of moving load problems.