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Size of matrix exported from Comsol : understanding?

Posted Sep 11, 2018, 3:46 a.m. EDT General, Mesh, Results & Visualization Version 5.3 1 Reply

Chuong Nguyen
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Deal all,

can you explain how to understand the size of stiffness matrix which is exported from comsol,

for example i have a 2d cantilever beam, discritized with nel_x x nel_y=20 x 10 => nnode_x x nnode_y = (20+1) x (10+1)=231 nodes, and ndofs=231 x 2=462 degree of freedoms,

so i expect the size of stiffness matrix will be K(full)=462x462, but the size exported from Comsol is: 1322x1322

you can following the matlab file for runing in Comsol server;

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1 Reply Last Post Sep 11, 2018, 7:08 a.m. EDT
Henrik Sönnerlind COMSOL Employee

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Posted: 6 years ago Sep 11, 2018, 7:08 a.m. EDT
Updated: 6 years ago Sep 11, 2018, 11:22 a.m. EDT

Hi,

You are probably using 2nd order serendipity elements (which is the default in Solid Mechanics).

(41*21 - 10*20)*2 = 1322

Regards,
Henrik

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Henrik Sönnerlind
COMSOL
Hi, You are probably using 2nd order serendipity elements (which is the default in Solid Mechanics). (41\*21 - 10\*20)\*2 = 1322 Regards, Henrik

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