MATLAB/SIMULINK Programs for Flutter
In this appendix, some sample MATLAB programs are given for the calculation of the aeroelastic behaviour of a binary flutter system and also its response to control surface and gust/turbulence inputs.
H.1 DYNAMIC AEROELASTIC CALCULATIONS
In Chapter 11 the characteristics of the flutter phenomenon were described using a binary aeroelastic system. The following code sets up the system equations, including structural damping if required, and then solves the eigenvalue problem for a range of speeds and plots the Vω and Vg trends.
% Flutter Chapter B04 Appendix % Sets up the aeroelastic matrices for binary aeroelastic model, % performs eigenvalue solution at desired speeds and determines the frequencies % and damping ratios % plots V_omega and V_g trends % and plots flutter conic solution % Initialize variables clear; clf % System parameters s = 7.5; % semi span c = 2; % chord m = 100; % unit mass / area of wing kappa_freq = 5; % flapping freq in Hz theta_freq = 10; % pitch freq in Hz xcm = 0.5*c; % position of centre of mass from nose xf = 0.48*c; % position of flexural axis from nose e = xf/c - 0.25; % eccentricity between flexural axis and aero centre (1/4 chord) velstart = 1; % lowest velocity velend = 180; % maximum velocity velinc =0.1; % velocity increment a = 2*pi; % 2D lift curve slope rho = 1.225; % air density Mthetadot = -1.2; % unsteady aero damping term M = (m*c^2 - 2*m*c*xcm)/(2*xcm); % leading edge mass term damping_Y_N = 1; % ...