Full nonlinear simulation of helicopter coupled rotor-fuselage motion using MATLAB Symbolic processor and dynamic simulation

Abstract

This thesis formulates the full nonlinear equations of motion for determining the stability of helicopter coupled rotor-fuselage motion utilizing MATLAB(registered)'s Symbolic Math Toolbox. Using the extended symbolic processor toolbox, the goal of this work was to eliminate the time consuming process of convening Fortran or C code generated by the symbolic processor, MAPLE(registered) into a MATLAB(registered) useable format where it is further incorporated into an S-function' to be used in the dynamic simulation environment. The formulation of the equations of motion utilized in this process is unique in that it uses the complete set of nonlinear terms in the equations of motions without utilizing ordering schemes, small angle assumptions, linearizing techniques, or other simplifying assumptions. After derivation, the equations of motion are numerically integrated using the dynamic simulation software SIMULINK(registered) and a time history plot is generated of blade and fuselage motion. The equations of motion are regenerated with each time step allowing the adjustment of characteristic structural, blade and dampening properties. These time traces can be used to explore the effects of damping nonlinearities, structural nonlinearities, active control, individual blade control, and damper failure on ground resonance.