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Matlab LiveLink - Comsol Multiphysics- obtaining stresses of a beam Model
Posted 25 oct. 2021, 19:06 UTC−4 Structural & Acoustics, LiveLink for MATLAB, Structural Mechanics 1 Reply
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Hello, I'm having issues reading the results of a beam model I solved with Comsol inside my MATLAB algorythm.
My algorythm:
mphopen('PRUEBA')
% mesh info [meshstats,meshdata] = mphmeshstats(model,'mesh1'); coord=meshdata.vertex; nnodos=size(coord,2); conect=meshdata.elem{2}; nelem=size(conect,2);
% Resultados of stress, shear, and transformation to global system. stress=mpheval(model,'beam.sn','dataset','dset1');
The mesh part works fine, I get the coordinates and conection I want, but it gives me a struct with empty fields whenever I try to ask for shear and stress:
struct with fields:
expr: {'beam.sn'}
d1: [1×0 double]
p: [3×0 double]
t: [4×0 int32]
ve: [0×1 int32]
unit: {'N/m^2'}
Also tried mphiterp just in case:
shear=mphinterp(model,'beam.txymax','dataset','dset1','coord',coord); Error using mphinterp mphinterp (0): Unable to perform assignment because the size of the left side is 1-by-3 and the size of the right side is 1-by-0.
I saved my comsol file and it works fine, I have values of stress and displacement, but I don't know why I can't read them on COMSOL.
Best Regards
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Hi Santiago
mpheval and mphinterp assumes you wish to extract data from domains.
For beams you want to extract data from edges. Hence you have to use the edim option.
Hence this is how you use mpheval:
data=mpheval(model,'beam.sn',"edim","edge")
You propably want to use mphinterp in most cases. Here is how to extract data from edge number 3:
c = mphgetcoords(model,'geom1','edge',3)
v = linspace(0,1,10) % 10 points along the edge.
coord = v.*c(:,1)+(1-v).*c(:,2) % lerp (linear interpolation)
dat = mphinterp(model,'beam.sn','edim','edge','coord',coord)
Lars Gregersen
Comsol Denmark