FRF Plotting
7 次查看(过去 30 天)
显示 更早的评论
I want to plot FRF vs Frequency graph.I have a matrix 'a' of acceleration & a force matrix 'f' both of 30000X1 size, collected in 3secs with a time step of 0.0001 sec.I am using the following steps to plot FRF. ffa=fft(a); fff = fft(f); frf, H=ffa./fff; aH =abs(H); x=0:0.1:30000; semilogy(aH) After plotting,I am not getting the correct first natural frequency at the first peak compared to the one I obtained from ANSYS (=14.5Hz).For plotting on Y-axis wether we have to take FRF in dB by using 20*log10(aH)?Where am I wrong in the procedure? Does the time steps have any role while finding fft?.
回答(1 个)
bym
2011-6-26
Your x-axis scaling is incorrect. When you do
semilogy(aH)
it plots the amplitude versus the matrix index. You need to scale the x axis. See
doc fft
for example and detailed explaination
0 个评论
另请参阅
类别
在 Help Center 和 File Exchange 中查找有关 Spectral Measurements 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!