FFT of vibration data, Help me please.

Dear friends

I have vibration data from the device, I need to convert it into Freq Domain (Magnitude vs Freq). I've tried several times and still stuck, I can't import that data into the formula/function. I've attached an excel file I got from the device. maybe you can download and see the excel files for complete information. Could you guys help me, what function/formula should I write? and how to find the max point in the plot?

Answer 1

[Star Strider]

Try this —

T1 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/994895/fantest.xlsx%20-%20Sheet2.xlsx', 'VariableNamingRule','preserve')

T1 = 717×6 table
    hours    Current    Voltage    axis x    axis y    axis z
    _____    _______    _______    ______    ______    ______

      1       0.182      228.8     -0.14     -0.25      0.84 
      2       0.181      228.8      -0.1     -0.22      0.84 
      3       0.182        229      0.07     -0.06      0.86 
      4       0.182      228.9      0.04     -0.12      0.86 
      5       0.181      228.7      0.02     -0.08      0.85 
      6       0.182      228.9      0.15     -0.01      0.86 
      7       0.182      229.1      0.02      -0.1      0.85 
      8       0.181      228.8      0.16      0.04      0.86 
      9       0.181      228.9      0.02     -0.12      0.84 
     10       0.181      228.6      0.25      0.14      0.89 
     11       0.181      228.7      0.19       0.1      0.87 
     12       0.181      228.9     -0.17     -0.23      0.84 
     13       0.181      228.8      0.17      0.09      0.88 
     14       0.182      229.1       0.3      0.17      0.89 
     15       0.182      229.2      0.29      0.12      0.87 
     16       0.182      229.5      0.12     -0.01      0.86 

VN = T1.Properties.VariableNames

VN = 1×6 cell array
    {'hours'}    {'Current'}    {'Voltage'}    {'axis x'}    {'axis y'}    {'axis z'}

L = size(T1,1);
% QQ1 = nnz(diff(T1{:,1}) ~= 1)
Ts = T1.hours(2) - T1.hours(1);                                     % Sampling Interval
Fs = 1/Ts;                                                          % Sampling Frequency
Fn = Fs/2;                                                          % Nyquist Frequency
NFFT = 2^nextpow2(L);                                               % For Efficiency
FT_T1 = fft(T1{:,2:end} - mean(T1{:,2:end}), NFFT)/L;               % Fourier Transform (Mean Subtracted To Show Other Peaks More Clearly)
Fv = linspace(0, 1, NFFT/2+1)*Fn;                                   % Frequency Vector
Iv = 1:numel(Fv);                                                   % Index Vector

figure
plot(Fv, abs(FT_T1(Iv,:))*2)
grid
xlabel('Frequency (hr^{-1})')
ylabel('Amplitude')
legend(VN{2:end}, 'Location','best')

NrSp = size(FT_T1,2);

NrSp = 5

figure
for k = 1:NrSp
    subplot(NrSp,1,k)
    plot(Fv, abs(FT_T1(Iv,k))*2)
    grid
    ylabel('Amplitude')
    title(VN(k+1))
end
xlabel('Frequency (hr^{-1})')

.

[Phakapol Tungboontina]

Thank you I really appreciate your help.

[Phakapol Tungboontina]

Thank you I really appreciate your help.

[Star Strider]

As always, my pleasure!

[Phakapol Tungboontina]

Can you help me another question that I post in topic How to conversion of Acceleration FFT to Velocity?