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How to reuse the result of a previous simulation as an input for the second simulation?

Posted 18 mars 2020, 23:34 UTC−4 Structural & Acoustics, General, Geometry, Mesh, Studies & Solvers, Structural Mechanics 6 Replies

Montassar Akrmi
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Hi, I am looking for the steps needed to reuse a deformed hyperelastic shape with stress results created in response to a prescribed displacement, for a second simulation with new boundary conditions. Thank you in advance,

6 Replies Last Post 18 juil. 2020, 17:07 UTC−4
Henrik Sönnerlind COMSOL Employee

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Posted: 5 years ago 19 mars 2020, 03:30 UTC−4

Hi Montassar,

Exactly what type of change is it that you are going to do to the boundary conditions?

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Henrik Sönnerlind
COMSOL
Hi Montassar, Exactly what type of change is it that you are going to do to the boundary conditions?
Montassar Akrmi
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Posted: 5 years ago 19 mars 2020, 12:38 UTC−4

Hi Mr Henrik

I am just trying to Disable the Prescribed Displacement of Study 1 Enable the Fixed Constraint Boundary Load of Study 2, and apply to the deformed shape with stress results of Study 1.

Hi Mr Henrik I am just trying to Disable the **Prescribed Displacement** of *Study 1* Enable the **Fixed Constraint** **Boundary Load** of *Study 2*, and apply to the deformed shape with stress results of *Study 1*.
Henrik Sönnerlind COMSOL Employee

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Posted: 5 years ago 20 mars 2020, 10:57 UTC−4

This is not trivial. Removing a constraint will for example usually give some springback.

Things are also very different if for example plastic deformations are involved (since for an elastic problem, the path to the final state is not interesting).

One way of removing a constraint smoothly is to implement it using a penaly formulation, and gradually remove the penalty factor. See also https://www.comsol.com/blogs/how-to-make-boundary-conditions-conditional-in-your-simulation

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Henrik Sönnerlind
COMSOL
This is not trivial. Removing a constraint will for example usually give some springback. Things are also very different if for example plastic deformations are involved (since for an elastic problem, the path to the final state is not interesting). One way of removing a constraint smoothly is to implement it using a penaly formulation, and gradually remove the penalty factor. See also
Haishan Tang
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Posted: 5 years ago 4 avr. 2020, 11:15 UTC−4

Hi, I would like to simulate the band gap of a deformed phononic crystal. Firstly, I will simulate the deformation of the porous structure under the external load, and then, the deformed structure with initial stresses can be useded as the new geometric input for the next step. I see the details in the following blog post: www.comsol.com/blogs/how-to-reuse-a-deformed-shape-as-a-geometry-input/. However, when I use this technique, several strange lines are at the surface of the input model. Moreover, this input model has no initial stresses. So how can I export the deformed structure with initial stresses for next study? Do you have other methods? Thanks in advance. Best regards, Haishan Tang

Hi, I would like to simulate the band gap of a deformed phononic crystal. Firstly, I will simulate the deformation of the porous structure under the external load, and then, the deformed structure with initial stresses can be useded as the new geometric input for the next step. I see the details in the following blog post: www.comsol.com/blogs/how-to-reuse-a-deformed-shape-as-a-geometry-input/. However, when I use this technique, several strange lines are at the surface of the input model. Moreover, this input model has no initial stresses. So how can I export the deformed structure with initial stresses for next study? Do you have other methods? Thanks in advance. Best regards, Haishan Tang

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Montassar Akrmi
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Posted: 5 years ago 15 avr. 2020, 22:12 UTC−4
Updated: 4 years ago 9 juil. 2020, 06:37 UTC−4

Hi Haishan Tang In fact, your question is what I'm looking for. unfortunately, so far I haven't been able to find an answer, maybe Mr. Henrik's suggestions might help, but I think it is not the exact or simplest way to solve the problem.

Hi Haishan Tang In fact, your question is what I'm looking for. unfortunately, so far I haven't been able to find an answer, maybe Mr. Henrik's suggestions might help, but I think it is not the exact or simplest way to solve the problem.
Montassar Akrmi
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Posted: 4 years ago 18 juil. 2020, 17:07 UTC−4
Updated: 4 years ago 18 juil. 2020, 17:08 UTC−4

Regarding the last update of my inquiry, I solved by some simple steps, First, instead of two 'Stationary' simulations, I used one 'Time-dependent' to integrate a sequence of simulations. Second, Instead of the 'Prescribed Displacement', I used 'Boundary Load', and by this, I could eliminate the applied force gradually during the simulation by using an 'Interpolation' function, which is not possible by using 'Prescribed Displacement'. (The same idea of M. Henrik I think.) And third, placing anchors to hold the new deformed shape during the simulation. I hope this will help the future reader,

Regarding the last update of my inquiry, I solved by some simple steps, First, instead of two 'Stationary' simulations, I used one 'Time-dependent' to integrate a sequence of simulations. Second, Instead of the 'Prescribed Displacement', I used 'Boundary Load', and by this, I could eliminate the applied force gradually during the simulation by using an 'Interpolation' function, which is not possible by using 'Prescribed Displacement'. (The same idea of M. Henrik I think.) And third, placing anchors to hold the new deformed shape during the simulation. I hope this will help the future reader,

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