Abstract:

The parametric vibration problem is one of the fundamental problems in helicopter dynamics. The rotor blade flap bending differential equation and lag bending differential equation both are complex parametric vibration problems, especially the latter one. It is rather difficult to solve such a kind of blade motion equations. Two numerical approaches have been developed for solving the parametic equations. One is the periodic function method or harmonic method, and the other is the linear acceleration step-by-step integration procedure. The former has the advantage in saving CPU time and computer storge,but it can not be used to deal with the unsteady motion and investigate the infl'uence given by the initial condition. The linear acceleration step-by-step integration procedure can be used for steady or unsteady vibr at ion, bu t it takes more CPU time than the former. Two examples have been presented. They are solved by the periodic function method and linear accleration step-by-step integration procedure, respectively.

Key words: parametric vibration problem, periodic function method, linear acceleration, step-by-step integration procedure