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Information carried by 'Initial values' in solid module

Posted Jul 3, 2014, 1:27 a.m. EDT Structural Mechanics Version 4.3 3 Replies

Sting Cozlov
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Hi there,
My project is to simulate the solid deformation in two steps. In each step, one solid module is solved. In the 2nd step, I specify the initial displacement field and velocity field are from the 1st step.
My question is: If I just specify the displacement and velocity this way, does it mean that the strain and stress information are lost? I mean, is the strain or stress consistent in the two steps?
3 Replies Last Post Jul 4, 2014, 1:33 a.m. EDT
Henrik Sönnerlind COMSOL Employee

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Posted: 1 decade ago Jul 3, 2014, 8:10 a.m. EDT
Hi,

As long as the problem is elastic, there is no problem. The strains (and thus the stresses) are computed from the initial displacements.

It there are inelastic strains in the first Solid Mechanics interface, the situation becomes more complicated, since they must also be known to the second physics interface.

Regards,
Henrik
Hi, As long as the problem is elastic, there is no problem. The strains (and thus the stresses) are computed from the initial displacements. It there are inelastic strains in the first Solid Mechanics interface, the situation becomes more complicated, since they must also be known to the second physics interface. Regards, Henrik
Sting Cozlov
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Posted: 1 decade ago Jul 3, 2014, 8:28 p.m. EDT
Thank you very much
Thank you very much
Sting Cozlov
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Posted: 1 decade ago Jul 4, 2014, 1:33 a.m. EDT
Hi Henrik,
I come up with another related problem: How to keep a record of all the information at one time?

In my project, I use solid module and Darcy flow model to simulate the Biot theory.

First I run the coupled model to get an stable status(p_initial, u_initial), and use this status as a reference for later use, i.e. some equations involve (p-p_initial) or(sx-sx_initial) . Then I change the boundary condition, and let the simulation continue.

My problem is how to keep and then how to use this reference status? Previously, I run two sets of models: model 1(with p_initial and u_initial as independent variables) runs to equilibrium, and the running time is (0 to 100 s); model 2 uses the results from model 1 as initial values, and proceeds. In model 2, I used some equations involve (p-p_initial).

I just noticed maybe it's wrong to simply use (p-p_initial), since they are not corresponding to the same time.

Can you give me some clue on how to use the information at a specific time step?
Hi Henrik, I come up with another related problem: How to keep a record of all the information at one time? In my project, I use solid module and Darcy flow model to simulate the Biot theory. First I run the coupled model to get an stable status(p_initial, u_initial), and use this status as a reference for later use, i.e. some equations involve (p-p_initial) or(sx-sx_initial) . Then I change the boundary condition, and let the simulation continue. My problem is how to keep and then how to use this reference status? Previously, I run two sets of models: model 1(with p_initial and u_initial as independent variables) runs to equilibrium, and the running time is (0 to 100 s); model 2 uses the results from model 1 as initial values, and proceeds. In model 2, I used some equations involve (p-p_initial). I just noticed maybe it's wrong to simply use (p-p_initial), since they are not corresponding to the same time. Can you give me some clue on how to use the information at a specific time step?

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