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How to get Eigenfrequency values with Matlab LiveLink

Posted Aug 31, 2010, 5:26 p.m. EDT Interfacing, Structural Mechanics Version 4.4 4 Replies

Mark Roy
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Hello everyone,

I've got my model working with Matlab LiveLink and one of my studies computes mechanical eigenfrequency of a MEMS structure. I'm trying to figure out how to get the value of the computed eigenfrequencies from the solution into Matlab.

I've been trying to use the mpheval or mphglobal commands but I do not know what variable to use in the expressions.
Any help would be greatly appreciated.

Thanks.
Mark Roy
4 Replies Last Post Apr 3, 2015, 11:10 p.m. EDT
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Micke Malmström
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Posted: 1 decade ago Nov 22, 2010, 7:37 a.m. EST
did you get it?
did you get it?
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Nov 22, 2010, 3:21 p.m. EST
Hi

when you have several solutions (parametric sweep ,eigenfrequency, time dependent, then you must use the "solnum" to access them in order, check also the with() and at() operators (or whatever they are now clled in V4.

Sorry cannot tell more, I havent really had time to use Livelink yet, the new features of V4 have allowed me so long to survive well without matlab ;)

--
Good luck
Ivar
Hi when you have several solutions (parametric sweep ,eigenfrequency, time dependent, then you must use the "solnum" to access them in order, check also the with() and at() operators (or whatever they are now clled in V4. Sorry cannot tell more, I havent really had time to use Livelink yet, the new features of V4 have allowed me so long to survive well without matlab ;) -- Good luck Ivar
Mark Roy
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Posted: 1 decade ago Nov 22, 2010, 7:48 p.m. EST
After setting up and running an eigenfrequency simulation, I figured out that you can use mpheval to get the value from the dataset.

ie:

model.sol.create('sol2');
... setup solution features for eigenfrequency, number of steps, tolerance, etc...
model.sol('sol2').attach('std2');

model.result.create('pg2', 2);
model.result('pg2').set('data', 'dset2');
model.result('pg2').feature.create('surf1','Surface');
model.sol('sol2').runAll;
model.result('pg2').run;

eval = mpheval(model,'smpn.freq','Dataset','dset2','edim',0,selection',1);
eigenfreq = eval.d1;

Thats basically what I've done and it seems to work. The reason everything is number 2 is because I also have another solution for steady state response.

Hope that helps.
After setting up and running an eigenfrequency simulation, I figured out that you can use mpheval to get the value from the dataset. ie: model.sol.create('sol2'); ... setup solution features for eigenfrequency, number of steps, tolerance, etc... model.sol('sol2').attach('std2'); model.result.create('pg2', 2); model.result('pg2').set('data', 'dset2'); model.result('pg2').feature.create('surf1','Surface'); model.sol('sol2').runAll; model.result('pg2').run; eval = mpheval(model,'smpn.freq','Dataset','dset2','edim',0,selection',1); eigenfreq = eval.d1; Thats basically what I've done and it seems to work. The reason everything is number 2 is because I also have another solution for steady state response. Hope that helps.
Bruno Rango
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Posted: 9 years ago Apr 3, 2015, 11:10 p.m. EDT
Hi,

I'm facing a similar problem: I'm performing a simple eigenfrequency study of a cable, repeating it for several values of a particular parameter involved. I do this by programing a loop in Matlab Livelink.
I'am interested in the first three eigenfrquencies, so I need to store them for each value of the parameter simulated. I couldn't manage to get those values into Matlab.

I would really appreciate your help.

Thank you in advance.

Bruno.
Hi, I'm facing a similar problem: I'm performing a simple eigenfrequency study of a cable, repeating it for several values of a particular parameter involved. I do this by programing a loop in Matlab Livelink. I'am interested in the first three eigenfrquencies, so I need to store them for each value of the parameter simulated. I couldn't manage to get those values into Matlab. I would really appreciate your help. Thank you in advance. Bruno.

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