fs = 20e3; % 采樣頻率
fn = 3e3; % 固有頻率
y0 = 5; % 位移常數
g = 0.1; % 阻尼系數
T = 0.01; % 重復周期
N = 4096; % 采樣點數
NT = round(fs*T); % 單周期采樣點數
t = 0:1/fs:(N-1)/fs; % 采樣時刻
t0 = 0:1/fs:(NT-1)/fs; % 單周期采樣時刻
K = ceil(N/NT)+1; % 重復次數
y = [];
for i = 1:K
y = [y,y0*exp(-g*2*pi*fn*t0).*sin(2*pi*fn*sqrt(1-g^2)*t0)];
end
y = y(1:N);
Yf = fft(y); % 頻譜
figure(1)
plot(t,y);
axis([0,inf,-4,5])
title('軸承故障仿真信號時域波形圖')
xlabel('Time(s)')
ylabel('Amplitude')
figure(2)
f = 0:fs/N:fs-fs/N;
plot(f/1e3,abs(Yf));
xlabel('Frequency(KHz)');
ylabel('\itY\rm(\itf\rm)')
title('軸承故障仿真信號幅度譜圖')