How to plot magnitude vs length from magnitude vs time plot

1 view (last 30 days)
Ramesh Bala on 4 Mar 2021
Answered: William Rose on 6 Mar 2021
I have the magnitude (amplitude) vs time Y.X values obtained.
I would like to know how can I plot magnitude vs length of the specimen in which I have obtained these signals?
Ramesh Bala on 5 Mar 2021
Or is there a way to plot wavenumber vs magnitude from it?

William Rose on 6 Mar 2021
If your strain versus time data is in a matrix e which is Nx6 (i.e. a column for each length, and N time points=N rows), then do this:
delamL=[5 10 20 30 40 50];
emax=max(e);
plot(delamL,emax);
If your matrix e is 6xN (a row for each length), then replace the second line with emax=max(e');
Here is an example of what I mean.
%BalaCode.m WCR 20210305
%Make some data like K. Bala's data
t=[0:.01:6]*1e-5;
e=zeros(length(t),6);
e(200:end,1)=12.5*cos(1.3e6*t(200:end) ).*(sin((t(200:end)-2e-5)*7.8e4)).^2;
e(200:end,2)=11.8*cos(1.3e6*t(200:end)+pi/2).*(sin((t(200:end)-2e-5)*7.8e4)).^2;
e(200:end,3)= 8*cos(1.3e6*t(200:end)-pi/2).*(sin((t(200:end)-2e-5)*7.8e4)).^2;
e(200:end,4)= 6.2*cos(1.3e6*t(200:end)+pi ).*(sin((t(200:end)-2e-5)*7.8e4)).^2;
e(200:end,5)= 7.2*cos(1.3e6*t(200:end)+pi/3).*(sin((t(200:end)-2e-5)*7.8e4)).^2;
e(200:end,6)= 8.2*cos(1.3e6*t(200:end)-pi/3).*(sin((t(200:end)-2e-5)*7.8e4)).^2;
%Make a plot like K. Bala's first plot
plot(t,e(:,1),'r-',t,e(:,2),'g-',t,e(:,3),'b-',t,e(:,4),'c-',t,e(:,5),'m-',t,e(:,6),'y-');
xlabel('Time (s)'); ylabel('Strain');
legend('5','10','20','30','40','50');
%Now the code to make the plot which K. Bala requested:
%Plot peak strain vs. delamination length
delamL=[5 10 20 30 40 50];
emax=max(e);
figure;
plot(delamL,emax,'k.-');
xlabel('Delam.Length (mm)'); ylabel('Max.Strain');
If using this forum in the future, I recommend supplying a short example of the kind of data you are working with, because it makes it a lot easier for others to assist you.