Method of multiple scales and identification of nonlinear structuraldynamic systems

A procedure has been developed t o identify the parameters of a nonlinear structural dynamic system with a single degree of freedom. A cubic nonlinearity has been assumed for purposes of illustration. In comparison t o the direct identification procedures, that depend on (a) either the availability of data on all four variables, namely, velocity, acceleration, displacement and the input t o the system or (b) the formulation of a numerical algorithm that can be used a t each iterative step, the developed procedure requires the data on only one of the field variables. The input t o the system is also treated a s an unknown. The results from the perturbation identification procedure have been compared with the results from two direct identification procedures.