Sedaghat - Department of Mechanical Engineering Isfahan University of Technology, Isfahan, Iran

This paper describes a preliminary investigation into the use of normal form theory for modelling large nonlinear dynamical systems. Limit cycle oscillations were determined for a simple two-degrees-of-freedom double pendulum system. The double pendulum system was reduced into its centre manifold before applying normal form computations. Normal forms were obtained using a period averaging method which is applicable to non-autonomous systems, more advantageous than the classical methods. Good agreement was obtained between the predicted results from the normal form theory and numerical simulations of the original system.

Normal Form Theory, Period Averaging, Limit Cycle Oscillations