close all; clear
Fs=3000; % Sampling frequency, [Hz]
t_stop=2.5; % stop simulation time
f_start=20; % Initial frequency [Hz]
f_stop=90; % Stop frequency {Hz}
a1=(2*pi*30)^2; % Linear angular frequency squared f0=1/2/pi=0.16 [Hz]
a3=2000; % Cubic nonlinear stiffness
a5=0.0; % Nonlinear stiffness
d=0.0; % Dead zone (Backlash)
b1=2*2.5; % Linear damping
b2=0; % Nonlinear damping
sim(‘s20′, t_stop); % Simulate a Simulink model
figure(1)
subplot(211)
plot(x);
axis tight
subplot(212)
plot(y,’k’);
grid on
axis tight
xlabel(‘Points, s’); ylabel(‘Displacement’);
title([‘Free vibration, a1=’ num2str(a1) ‘, b1=’ num2str(b1)])