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Mems Structure in 2d
Posted 11 nov 2009, 09:45 GMT-5 3 Replies
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Hello All,
I have build a structure in 2d using mems>> plane stress, Moving mesh (ale) and Mems>>elecrostaics modules. I am attaching the model to this discussion.Everytime i simulate the model i get the following error.
Exception:
com.femlab.jni.FlNativeException: Failed to evaluate expression
Messages:
Failed to evaluate expression
- Expression: diff(((FYg_smps*v_test)-(0))*(dvol),v_test)
Failed to evaluate variable
- Variable: FYg_smps
- Defined as: FY_smps
Failed to evaluate variable
- Variable: FY_smps
- Defined as: Fex_nTy_emes
Failed to evaluate variable
- Variable: Fex_nTy_emes
- Geometry: 1
- Dimension: 1
- Domain group: {131}
Stack trace:
at evaltree.cpp, row 757, ()
at evalnodes.cpp, row 754, ()
at evalnodes.cpp, row 754, ()
at xevalutil.cpp, row 2433, ()
at com.femlab.solver.FlSolver.femStatic(Native Method)
at com.femlab.solver.FemStatic.run(Unknown Source)
at com.femlab.server.FlRunner.run(Unknown Source)
at com.femlab.util.j.run(Unknown Source)
at com.femlab.util.ae.run(Unknown Source)
Can anyone please help me out with this.
I have build a structure in 2d using mems>> plane stress, Moving mesh (ale) and Mems>>elecrostaics modules. I am attaching the model to this discussion.Everytime i simulate the model i get the following error.
Exception:
com.femlab.jni.FlNativeException: Failed to evaluate expression
Messages:
Failed to evaluate expression
- Expression: diff(((FYg_smps*v_test)-(0))*(dvol),v_test)
Failed to evaluate variable
- Variable: FYg_smps
- Defined as: FY_smps
Failed to evaluate variable
- Variable: FY_smps
- Defined as: Fex_nTy_emes
Failed to evaluate variable
- Variable: Fex_nTy_emes
- Geometry: 1
- Dimension: 1
- Domain group: {131}
Stack trace:
at evaltree.cpp, row 757, ()
at evalnodes.cpp, row 754, ()
at evalnodes.cpp, row 754, ()
at xevalutil.cpp, row 2433, ()
at com.femlab.solver.FlSolver.femStatic(Native Method)
at com.femlab.solver.FemStatic.run(Unknown Source)
at com.femlab.server.FlRunner.run(Unknown Source)
at com.femlab.util.j.run(Unknown Source)
at com.femlab.util.ae.run(Unknown Source)
Can anyone please help me out with this.
Attachments:
3 Replies Last Post 14 nov 2009, 06:13 GMT-5
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Posted:
2 decades ago
Hey,
I took a look at your model. There are 2 problems:
1. For the y direction forces in plane-strain boundary conditions, you mistyped and put "Fex_nTy_emes", when it should be "Fes_nTy_emes"
2. You need to check the box that says "Edge load is defined as Force/Area using thickness." The Maxwell Stress tensor generates the force in these units.
After these two changes your model should work.
By the way, you seem to have some unnecessary B.C.s in you model. For example you are applying forces to boundaries which you have already defined as fixed. It might help speed up your model to get rid of any of these unnecessary items.
Good Luck,
Mike
I took a look at your model. There are 2 problems:
1. For the y direction forces in plane-strain boundary conditions, you mistyped and put "Fex_nTy_emes", when it should be "Fes_nTy_emes"
2. You need to check the box that says "Edge load is defined as Force/Area using thickness." The Maxwell Stress tensor generates the force in these units.
After these two changes your model should work.
By the way, you seem to have some unnecessary B.C.s in you model. For example you are applying forces to boundaries which you have already defined as fixed. It might help speed up your model to get rid of any of these unnecessary items.
Good Luck,
Mike
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Posted:
2 decades ago
Thank you. But now when i try to simulate it, the solution is not converging. I can see the following error.
================================================================================
Progress - Open Model: Wed Nov 11 18:36:52 EST 2009
================================================================================
================================================================================
Progress - Solve Problem: Wed Nov 11 18:37:38 EST 2009
================================================================================
fem.sol=femstatic(fem, ...
'solcomp',{'lm4','lm3','v','u','V','y','x'}, ...
'outcomp',{'lm4','lm3','v','u','V','y','x'});
--------------------------------------------------------------------------------
Number of degrees of freedom solved for: 136967
Unsymmetric matrix found.
Iter ErrEst Damping Stepsize #Res #Jac #Sol
1 1.1e+025 1.0000000 0.5 2 1 2
2 4.4 0.1000000 4.8 3 2 4
3 1.1 0.4315669 0.94 4 3 6
4 7.2 0.0136752 7.3 6 4 9
Error:
Failed to find a solution:
No convergence, even when using the minimum damping factor.
Returned solution has not converged.
================================================================================
Progress - Solve Problem: Wed Nov 11 18:46:50 EST 2009
================================================================================
fem.sol=femstatic(fem, ...
'init',init, ...
'solcomp',{'lm4','lm3','v','u','V','y','x'}, ...
'outcomp',{'lm4','lm3','v','u','V','y','x'});
--------------------------------------------------------------------------------
Number of degrees of freedom solved for: 136967
Unsymmetric matrix found.
Iter ErrEst Damping Stepsize #Res #Jac #Sol
1 2.8e+025 1.0000000 0.54 2 1 2
2 4.4 0.1000000 4.8 3 2 4
3 1.1 0.4315627 0.94 4 3 6
4 7.2 0.0136771 7.3 6 4 9
Error:
Failed to find a solution:
No convergence, even when using the minimum damping factor.
Returned solution has not converged.
I do not know the reason for this.
================================================================================
Progress - Open Model: Wed Nov 11 18:36:52 EST 2009
================================================================================
================================================================================
Progress - Solve Problem: Wed Nov 11 18:37:38 EST 2009
================================================================================
fem.sol=femstatic(fem, ...
'solcomp',{'lm4','lm3','v','u','V','y','x'}, ...
'outcomp',{'lm4','lm3','v','u','V','y','x'});
--------------------------------------------------------------------------------
Number of degrees of freedom solved for: 136967
Unsymmetric matrix found.
Iter ErrEst Damping Stepsize #Res #Jac #Sol
1 1.1e+025 1.0000000 0.5 2 1 2
2 4.4 0.1000000 4.8 3 2 4
3 1.1 0.4315669 0.94 4 3 6
4 7.2 0.0136752 7.3 6 4 9
Error:
Failed to find a solution:
No convergence, even when using the minimum damping factor.
Returned solution has not converged.
================================================================================
Progress - Solve Problem: Wed Nov 11 18:46:50 EST 2009
================================================================================
fem.sol=femstatic(fem, ...
'init',init, ...
'solcomp',{'lm4','lm3','v','u','V','y','x'}, ...
'outcomp',{'lm4','lm3','v','u','V','y','x'});
--------------------------------------------------------------------------------
Number of degrees of freedom solved for: 136967
Unsymmetric matrix found.
Iter ErrEst Damping Stepsize #Res #Jac #Sol
1 2.8e+025 1.0000000 0.54 2 1 2
2 4.4 0.1000000 4.8 3 2 4
3 1.1 0.4315627 0.94 4 3 6
4 7.2 0.0136771 7.3 6 4 9
Error:
Failed to find a solution:
No convergence, even when using the minimum damping factor.
Returned solution has not converged.
I do not know the reason for this.
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Posted:
2 decades ago
Hi
For me in addition to the comments aready given (I would also remove unnecesary boundaries and items) you have also to define the region for which the [ale] is active (air and not in the structure), as well as the [emes] same as the [ale]
Check carefully all BC to avoid double definitions, and do not foget to switch from physics to physcs (application mode) before setting sub-domain and boundary settings otherwisae you mix up things
Hope this helps, you have a nice model
Good luck
Ivar
For me in addition to the comments aready given (I would also remove unnecesary boundaries and items) you have also to define the region for which the [ale] is active (air and not in the structure), as well as the [emes] same as the [ale]
Check carefully all BC to avoid double definitions, and do not foget to switch from physics to physcs (application mode) before setting sub-domain and boundary settings otherwisae you mix up things
Hope this helps, you have a nice model
Good luck
Ivar