How to make an FRF with my accelerometer Data and FFT?
Dear, Matlab Users.
I have some inquiries about my accelerometer Data, that was processed by a Dewesoft Software.
So, I am gonna share my code and data, and I would like to know if there any suggestion to this resolution.
Sensitivy: 102 mV/g, or 10.40 mV/m/s^2
%Load data
clear all
load("C:UsersjoantDesktopField_ResearchMatlab_Codedata_test.mat")
whos
close all
%Plot the array according to the data
%Data of Channel 1
g1= transpose(Data1_352C33OLD)
t1= transpose(Data1_time_352C33OLD); % time
dt=1/(Sample_rate) % period
L=length(g1)
%Iterate
% Figure of Channel 1
figure(1)
plot(t1,g1,’b.-‘)
set(gca,’Fontsize’,14)
xlabel(‘time(s)’)
ylabel(‘g’)
xlim([min(t1) max(t1)])
%ylim([-6 6])
grid on
% Calculate Fourier transform of force
points=round((t1(L))/dt) %Calculate the points
A_F= g1; % This is the Force for setting in the fft.
freq= (0:1/(dt*points):(1-1/(2*points))/dt)’; %Hz
freq=freq(1:round(points/2+1),:); %Hz
length(freq)
length(fft(A_F))
%In this part I need help
A_fft=fft(g1); %without the conversion by 9.8 m/s^2
abs_A=abs(A_fft)
figure(4)
plot(freq,abs_A(1:length(freq)))
xlim([0 6]) % Because 5 Hz is 300 RPM
%ylim([-400 400])
xlabel(‘Frequency (Hz)’)
ylabel(‘g’)
%According to the practice in the laboratory the result is the following
%image.
This was my process to obtain the FFT, I would like to know if this process is correct?. Because when I plot this data is not the same values in y-axis that I had in the Dewesoft software.
Dewesoft fft(g) (attached) vs matlab fft(g) (attached)
Question #2
According to a Mechanical vibration book, I have the next equation to find the FRF. I applied this but my FRF y axis value is too high so, I don’t know If I didn’t applied correctly. That information is in my code and I use the following equation.
w= natural frequency = 31.42 rad/s^2.
I assumpted that A/F is g because according to the book, it says the next information: "Because the acceloremeter produces a voltage that is proportional to acceleration, we obtain the accelerance, A/F(w), from the dynamic signal analyzer".
My graph result:
This graph it doesn’t have sense, because I need values aroun of 0.15-0.17 in the first vibration mode. So, I would like to know if there any suggestion how to resolve this.
Best Regards,
Jo98.Dear, Matlab Users.
I have some inquiries about my accelerometer Data, that was processed by a Dewesoft Software.
So, I am gonna share my code and data, and I would like to know if there any suggestion to this resolution.
Sensitivy: 102 mV/g, or 10.40 mV/m/s^2
%Load data
clear all
load("C:UsersjoantDesktopField_ResearchMatlab_Codedata_test.mat")
whos
close all
%Plot the array according to the data
%Data of Channel 1
g1= transpose(Data1_352C33OLD)
t1= transpose(Data1_time_352C33OLD); % time
dt=1/(Sample_rate) % period
L=length(g1)
%Iterate
% Figure of Channel 1
figure(1)
plot(t1,g1,’b.-‘)
set(gca,’Fontsize’,14)
xlabel(‘time(s)’)
ylabel(‘g’)
xlim([min(t1) max(t1)])
%ylim([-6 6])
grid on
% Calculate Fourier transform of force
points=round((t1(L))/dt) %Calculate the points
A_F= g1; % This is the Force for setting in the fft.
freq= (0:1/(dt*points):(1-1/(2*points))/dt)’; %Hz
freq=freq(1:round(points/2+1),:); %Hz
length(freq)
length(fft(A_F))
%In this part I need help
A_fft=fft(g1); %without the conversion by 9.8 m/s^2
abs_A=abs(A_fft)
figure(4)
plot(freq,abs_A(1:length(freq)))
xlim([0 6]) % Because 5 Hz is 300 RPM
%ylim([-400 400])
xlabel(‘Frequency (Hz)’)
ylabel(‘g’)
%According to the practice in the laboratory the result is the following
%image.
This was my process to obtain the FFT, I would like to know if this process is correct?. Because when I plot this data is not the same values in y-axis that I had in the Dewesoft software.
Dewesoft fft(g) (attached) vs matlab fft(g) (attached)
Question #2
According to a Mechanical vibration book, I have the next equation to find the FRF. I applied this but my FRF y axis value is too high so, I don’t know If I didn’t applied correctly. That information is in my code and I use the following equation.
w= natural frequency = 31.42 rad/s^2.
I assumpted that A/F is g because according to the book, it says the next information: "Because the acceloremeter produces a voltage that is proportional to acceleration, we obtain the accelerance, A/F(w), from the dynamic signal analyzer".
My graph result:
This graph it doesn’t have sense, because I need values aroun of 0.15-0.17 in the first vibration mode. So, I would like to know if there any suggestion how to resolve this.
Best Regards,
Jo98. Dear, Matlab Users.
I have some inquiries about my accelerometer Data, that was processed by a Dewesoft Software.
So, I am gonna share my code and data, and I would like to know if there any suggestion to this resolution.
Sensitivy: 102 mV/g, or 10.40 mV/m/s^2
%Load data
clear all
load("C:UsersjoantDesktopField_ResearchMatlab_Codedata_test.mat")
whos
close all
%Plot the array according to the data
%Data of Channel 1
g1= transpose(Data1_352C33OLD)
t1= transpose(Data1_time_352C33OLD); % time
dt=1/(Sample_rate) % period
L=length(g1)
%Iterate
% Figure of Channel 1
figure(1)
plot(t1,g1,’b.-‘)
set(gca,’Fontsize’,14)
xlabel(‘time(s)’)
ylabel(‘g’)
xlim([min(t1) max(t1)])
%ylim([-6 6])
grid on
% Calculate Fourier transform of force
points=round((t1(L))/dt) %Calculate the points
A_F= g1; % This is the Force for setting in the fft.
freq= (0:1/(dt*points):(1-1/(2*points))/dt)’; %Hz
freq=freq(1:round(points/2+1),:); %Hz
length(freq)
length(fft(A_F))
%In this part I need help
A_fft=fft(g1); %without the conversion by 9.8 m/s^2
abs_A=abs(A_fft)
figure(4)
plot(freq,abs_A(1:length(freq)))
xlim([0 6]) % Because 5 Hz is 300 RPM
%ylim([-400 400])
xlabel(‘Frequency (Hz)’)
ylabel(‘g’)
%According to the practice in the laboratory the result is the following
%image.
This was my process to obtain the FFT, I would like to know if this process is correct?. Because when I plot this data is not the same values in y-axis that I had in the Dewesoft software.
Dewesoft fft(g) (attached) vs matlab fft(g) (attached)
Question #2
According to a Mechanical vibration book, I have the next equation to find the FRF. I applied this but my FRF y axis value is too high so, I don’t know If I didn’t applied correctly. That information is in my code and I use the following equation.
w= natural frequency = 31.42 rad/s^2.
I assumpted that A/F is g because according to the book, it says the next information: "Because the acceloremeter produces a voltage that is proportional to acceleration, we obtain the accelerance, A/F(w), from the dynamic signal analyzer".
My graph result:
This graph it doesn’t have sense, because I need values aroun of 0.15-0.17 in the first vibration mode. So, I would like to know if there any suggestion how to resolve this.
Best Regards,
Jo98. fft, frf, plot MATLAB Answers — New Questions
