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Uniaxial compression test on representative foam: symmetries!
Posted 24 lug 2012, 09:10 GMT-4 Structural Mechanics Version 4.2a 2 Replies
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Hello everyone,
I came trough this problem and since I'm quite a new COMSOL user perhaps someone can help me.
I’m trying to reproduce an uniaxial compression test (structural mechanics) on a simplified cellular material (cell is represented by tetrakaidecahedron). Cells edges are modeled as beams.
In order to reproduce the periodic conditions on the unloaded faces I have to apply symmetries boundary conditions. At the first three orthogonal faces generic symmetries were applied (see attached file) . At the upper face a displacement is imposed (load condition).
At the other two (lateral) faces I would like to apply a symmetry-like condition (in plane translations and orthogonal rotation allowed) but with a moving reference plane (translated in the perpendicular to the sample direction). Practically I would reproduce the warping effect keeping the lateral faces planar. Simple symmetries may not reproduce this condition since lateral displacement would be locked.
Could anyone please help me with this problem?
Thank you!
Claudio D'Angelo
I came trough this problem and since I'm quite a new COMSOL user perhaps someone can help me.
I’m trying to reproduce an uniaxial compression test (structural mechanics) on a simplified cellular material (cell is represented by tetrakaidecahedron). Cells edges are modeled as beams.
In order to reproduce the periodic conditions on the unloaded faces I have to apply symmetries boundary conditions. At the first three orthogonal faces generic symmetries were applied (see attached file) . At the upper face a displacement is imposed (load condition).
At the other two (lateral) faces I would like to apply a symmetry-like condition (in plane translations and orthogonal rotation allowed) but with a moving reference plane (translated in the perpendicular to the sample direction). Practically I would reproduce the warping effect keeping the lateral faces planar. Simple symmetries may not reproduce this condition since lateral displacement would be locked.
Could anyone please help me with this problem?
Thank you!
Claudio D'Angelo
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2 Replies Last Post 26 lug 2012, 01:52 GMT-4
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Posted:
1 decade ago
Hi Claudio,
Instead of symmetry condition where u_Normal = 0, set u_Normal everywhere on the face equal to say u_1 where u_1 is the displacement of one node. You should use a Model Coupling operator for that. That way the whole face will move together in the normal direction. You can add rotational terms as well if you want that plane to also rotate.
Note that a general periodic constraint is more complex because the nodes on one face are not totally free to move within the plane. They are also constrained by the motion of the nodes on the opposing face in order not to violate periodic continuity.
Nagi Elabbasi
Veryst Engineering
Instead of symmetry condition where u_Normal = 0, set u_Normal everywhere on the face equal to say u_1 where u_1 is the displacement of one node. You should use a Model Coupling operator for that. That way the whole face will move together in the normal direction. You can add rotational terms as well if you want that plane to also rotate.
Note that a general periodic constraint is more complex because the nodes on one face are not totally free to move within the plane. They are also constrained by the motion of the nodes on the opposing face in order not to violate periodic continuity.
Nagi Elabbasi
Veryst Engineering
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Posted:
1 decade ago
Dear Nagi,
thank you for your kind reply.
By defining a coupling factor "average" on the boundary nodes and applying that value to the prescribed displacement it seems to work. I will also apply rotational constrain to that faces in order to reproduce continuity.
Thank you again.
Claudio D'Angelo
thank you for your kind reply.
By defining a coupling factor "average" on the boundary nodes and applying that value to the prescribed displacement it seems to work. I will also apply rotational constrain to that faces in order to reproduce continuity.
Thank you again.
Claudio D'Angelo