can you please help in how to calculate area of each loop in hysteria graph separately using Matlab

[Star Strider]

You need to supply the data that created that plot.

You also need to describe the experiment or observation that created those data.

What are the variables? (One is obviously ‘Drift ratio %’). What is the other? What is ‘UHPC’?

[Ali Ehsani yeganeh]

how can I send you the data ?

the other vraible is load. the UHPC is the name of specimen high performance concrete.

that is result of cyclic loading of a structure.

[Star Strider]

‘how can I send you the data ?’

Post (attach it) to a Comment here, along with any other relevant information. That way, everyone gets to see it and work with it.

[Ali Ehsani yeganeh]

excel data file

[Star Strider]

What are the 8 columns of the data (many of which are NaN)?

I do not understand what:

'MTS793|MPT|ENU|1|2|.|/|:|1|0|0|A'

are, and I doubt others here will either.

[Ali Ehsani yeganeh]

that is the name of the test machine for the specimens,and those columns are time, load, deflection and drift ratio. basically column B and C should give same plot as I posted here.

Answer 1

[Star Strider]

I managed to identify the beginning and ending indices for each complete loop (at least as I define them) as the ‘comzx’ vector, so that may be the limit of my contribution here.

Try this:

[D,S] = xlsread('UHPC-FLEX-FATIGUE.xlsx');

zci = @(v) find(v(:).*circshift(v(:), [-1 0]) <= 0);                            % Returns Approximate Zero-Crossing Indices Of Argument Vector

loadidx = zci(D(:,2));                                                          % Zero-Crossing Indicess Of ‘Load’
lt0idx = find(D(:,3) <= 0);                                                     % Indices For Deflection < 0
comzx = intersect(loadidx,lt0idx);                                              % Start & End Indices For Each Complete Loop

loopareas = cumtrapz(flipud(D(:,1)), flipud(D(:,2)).^2+flipud(D(:,3)).^2);      % Guess At Area Calculation
validareas = diff(flipud(loopareas(comzx)));                                    % Guess At Individual Loop Areas

figure
plot3(D(:,2), D(:,3),D(:,1))
hold on
plot3(D(comzx,2), D(comzx,3), D(comzx,1), '.r')
hold off
grid
xlabel('Load')
ylabel('Deflection')
legend('Data','Loop Start-End')

You will likely have to decide for yourself how to calculate the areas. (I integrated the sum of the squares of ‘Load’ and ‘Deflection’ with respect to time.) Flipping the vectors upside-down (the flipud calls) is necessary because integrating them without first doing results in a cumtrapz output vector that are uniformly NaN.

I have no idea if the area calculations are correct. However this is your research, so I leave the correct calculation to you. You can likely find a reference for that in the literature.

[Ali Ehsani yeganeh]

thank you so much i will go througth the coding to understand it. again thank you.

[Star Strider]

My pleasure.

If my Answer helps you solve your problem, please Accept it!