The Response of Mechanical Systems to Random Excitations

Ir. i oduction Mechanical systems are not always excited by a harmonic force of fixed frequency and amplitude. Often the excitation input is of random nature, and the response of the system displays no orderly trends. Instan-taneous values and phase are meaningless in such cases, and the problem must be treated from a statistical approach It is the purpose of this paper to outline such an approach as related to the dynamic response of structures. The mathematical basis of the statistical technique has been exhaus-tively treated by Rice. Engineering applications of statistical concepts have been followed with notable advances in fields such as communisaüon Applications to the structural field have only recently received attention, 2 with treatment of problems of naturally statistical nature such as buffeting" and fatigue / With greater utilization of rocket and jet engines, the statis