Beam excited by a shaker

May 9, 2013, 9:03 am

≫ Next: Cannot open native file error in COMSOL 4.2

≪ Previous: What is the method to calculate error?

Hi All,

I aim to model a simple beam excited by a shaker. I am using the Solid Mechanics.
I would like to know how big is the displacement of a particular mode (eg first flexural) when I excite the beam in resonance.

I found the eigenfrequencies using the study step EIGENFREQUENCY. Let's talk about just one of them, eg 100Hz

now I would like to excite the beam with this frequency I have just found. How to do that?

What I tried to do was to use the study step FREQUENCY DOMAIN choosing the frequencies 100Hz and to compute it.

I have this error:

Failed to find a solution.
The relative residual (0.25) is greater than the relative tolerance (0.001).
Returned solution is not converged.

I can imagine it is for the reason that using a stationary solver, without damping, at resonance it can't converge. but, in this case, how can I do? Is it wrong to use he stationary? What abut the frequency dmain as study step rather than FREQUENCY DOMAIN MODAL?

Thanks in advance

Fabrizio

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Cannot open native file error in COMSOL 4.2

June 26, 2013, 8:20 am

≫ Next: Solution Not Converging - Simple Cantilever Switch Pull In Voltage Calculation error

≪ Previous: Beam excited by a shaker

Hello,

When i am trying to perform a run of a model in COMSOL 4.2 this error appers

Cannot open native file:
Details: C:\Users\________\comsol\recoveries

Can anyone please tell me why this error appears?

Thank you very much!!!!

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Solution Not Converging - Simple Cantilever Switch Pull In Voltage Calculation error

July 3, 2013, 5:51 am

≫ Next: meshing error

≪ Previous: Cannot open native file error in COMSOL 4.2

Hi, I am trying to simulate a simple switch with a cantilever beam, an oxide anchor and a substrate. My aim is to find out the pull in voltage of the switch. I used the tutorial "biased_resonator_2d_pull_in" from MEMS module>Actuators. I went through many forums and based on some suggestions given there, I tried changing the initial conditions of dependent variable and mesh refinement. Nevertheless, I could not obtain the required graph which shows the pull in voltage. While playing around with the parameters already mentioned, these were the errors that I got.

1. "Returned solution is not converged"
2. "NaN or Inf found when solving linear system using SOR"

Please help if anyone has succeeded in figuring out how to calculate the pull in voltage of MEMS switches with COMSOL.
Thanks in advance.

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meshing error

March 7, 2011, 8:08 am

≫ Next: CAD import and meshing error

≪ Previous: Solution Not Converging - Simple Cantilever Switch Pull In Voltage Calculation error

hi,
i got following error several times with different models while meshing.
'failed to respect boundary element on geometry edge'.
may i know the reason behind this?

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CAD import and meshing error

May 9, 2011, 1:57 pm

≫ Next: Error Message: Undefined Value Found

≪ Previous: meshing error

Hi everyone,

I am trying to import a .sat file to COMSOL. Even though in the CAD-programme (Rhino) I am able to form a union, it fails in COMSOL. If I simplify my model, so that the union works, the meshing no longer works! Either, it fails to mesh a face of the structure or I get "internal error with code 900". Furthermore, the problem is that, if I get my complicated model, and make a union in Rhino, COMSOL fails to import the geometry all in all!

I have been rebuilding my CAD-model, so that all the surfaces and solids would be well-defined.

Therefore, I would like to ask for some help in importing .sat-files to COMSOL. Anyone has experience on it?

And, what could be the error in the meshing process?

Henna

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Error Message: Undefined Value Found

June 23, 2011, 5:11 pm

≫ Next: Error 1095: Failure to load (Not enough server storage space)

≪ Previous: CAD import and meshing error

Hi!

We recently installed COMSOL 4.2. (We've been using COMSOL 3.5a, so we are trying to create the same model on COMSOL 4.2. The model works with COMSOL 3.5a version)

Basically, I am working on "Transport of Diluted Species" module, where I want periodic condition from left and right of my slab of brick and mortar geometry.

I set my bricks to be impermeable by putting zero diffusivity, and I put a value for mortar geometry. And I set top mortar to have a certain concentration (infinite source), and I set the bottom mortar to have zero concentration (infinite sink). My brick and mortar is a 2D geometry, and I put periodic condition on left and right side of my rectangular slab. I basically want my solutes to go through mortar pathway, but for some reasons, it's not working on this model.

I guess I am doing something wrong, I got below error message from COMSOL 4.2

Undefined value found.
- Detail: Undefined value found in the stiffness matrix.
There are 253 equations giving NaN/Inf in the matrix rows for the variable mod1.c
at coordinates: (4.01e-005,1.75e-005), (4.01e-005,1.74437e-005), (4.01e-005,1.73683e-005), (4.01e-005,1.72675e-005), (4.01e-005,1.71327e-005), ...
and similarly for the degrees of freedom, NaN/Inf in the matrix columns

What am I doing wrong?

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Error 1095: Failure to load (Not enough server storage space)

July 11, 2011, 3:53 pm

≫ Next: Error saving file

≪ Previous: Error Message: Undefined Value Found

I have a problem opening COMSOL 3.5a models.
It was working fine, but suddenly, it couldn't load my models starting last Friday.
Last time, I had the same problem, but the problem was resolved by turning computer on and off.
So I turned my computer off over the weekend and tried, but this time it's still not working.

I looked up the error message online, but none of the solutions is applicable to our model since we created our models on COMSOL 3.5a version and never transferred the model from one person to another.

Since it is possible that the server does not have enough space, I tried opening this on desktop, but it didn't work.

When I tried to copy the model to my document or my private server storage, it won't copy because of lack of storage space.

Sincerely,
Jinhwa

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Error saving file

July 22, 2011, 7:14 pm

≫ Next: Material Adding - Boolean Operation Error

≪ Previous: Error 1095: Failure to load (Not enough server storage space)

Hello,

My model is based on a geometry imported from a .stp file. I use stationary electric current physics. When it solves the problem, there is a message saying "error saving file" and the result returns 0 everywhere. I cleared files from my disc for making enough space, but it still won't work.

Anyone knows what this error means and how to make it work?

Thanks in advance

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Material Adding - Boolean Operation Error

August 8, 2011, 12:03 am

≫ Next: Example Model cannot converge: boltzmann_argon

≪ Previous: Error saving file

Hi Guys,

First post from me, a newbie at COMSOL.

Problem:
I imported a CAD model into COMSOL, and tried to specify material of different parts of this model.

When I tried to do this, COMSOL says "Boolean geometry operation failed" and doesn't allow me
to specify any part of this model.

Can anyone explain what's happening here?

I appreciate your time when you help me, and I'll try my best to help the rest of this community too
when I'm experienced enough.

Much Thanks

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Example Model cannot converge: boltzmann_argon

November 24, 2011, 12:39 am

≫ Next: 3d laminar flow - solver problem: Segregated group 1.

≪ Previous: Material Adding - Boolean Operation Error

Hi,

When I restart to solve the boltzmann_argon model, I got some error messages as below:

Failed to find a solution for the initial parameter.

Maximum number of Newton iterations reached.

Returned solution is not converged.

How to tune to get the right results?

(My version is 4.2)

Thanks~

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3d laminar flow - solver problem: Segregated group 1.

January 1, 2012, 10:52 am

≫ Next: Estimated error in the energy norm OR the error norm.

≪ Previous: Example Model cannot converge: boltzmann_argon

Hi

I´m simulating the convection heat transfer in a pipe. The external surface of the pipe receive solar radiation to heat the fluid that is flowing.

I start my model with the laminar flow and after I can validate this part of my model I'll put the heat transfer in the pipe to the fluid. But some problems ocurred when i started to comput my model.
When I selected the inlet boundary condition to "velocity" I obtained successful simulation with initial velocity field "0". When change the initial velocity field the simulation dont converge. I dont understand this.

I have changed the inlet boundary condition to "laminar inflow - flow rate", because in the real model I have just the values of fluid flow. At the first time that I tried to simulate occured the following error : "Segregated solver steps do not involve all components." So I added the variables in the segregated step and now the following error is occuring in the simulation:

Failed to find consistent initial values.
Segregated group 1

Matrix has zero on diagonal.
Last time step is not converged.

I dont understand why this error is occuring. I tried to change the initial values but the error persists.
Can someone help me? I put my file in the attach.

Another thing I would ask is how to plot the velocity profile along the pipe?

thanks.

Gustavo

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Estimated error in the energy norm OR the error norm.

October 9, 2012, 1:53 pm

≫ Next: Error : Failed to find consistent initial values

≪ Previous: 3d laminar flow - solver problem: Segregated group 1.

Hello everyone,

I am having trouble with something that I can't seem to find any help about in COMSOL support. I only see it mentioned very little and not in very much detail in the help documents. I am wondering how to calculate the estimated error in the energy norm (I've seen references to the "error norm" on this site, is that the same thing?). By energy norm, I am referring to the definition found in these two texts (if you are not familiar with the term, if you are, sorry for insulting your knowledge of the FEM :) www.math.cornell.edu/~demlow/425/chap5.pdf or www.cs.rpi.edu/~flaherje/pdf/fea7.pdf.

Thank you for your help in advance,

John

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Error : Failed to find consistent initial values

October 16, 2012, 5:56 am

≫ Next: 3d Core, Error: Unknown function or operator

≪ Previous: Estimated error in the energy norm OR the error norm.

Hi !

I'm trying to simulate a magnetic dipole in time domain but I'm encoutring an error. The model is fonctional in frequency domain but when I use the time dependent study, the progress window shows that the simulation stucks in the constraint handling/creating multigrid levels step and soon after I get the attached below error message.

I'd be grateful for any kind of help and thanks for you eventual support !

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3d Core, Error: Unknown function or operator

October 31, 2012, 12:41 pm

≫ Next: Simulation error

≪ Previous: Error : Failed to find consistent initial values

Hello,

I have modeled a 3d core with a coil and the coil I have declared Muti-turn coil.
And in the simulation I have the following error:

Unknown function or operator
Name: mod1.mf.mtcd1.intp_edge
Feature: Stationary Slover 1 (soll/s1)
Error: Unknown function or operator

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Simulation error

November 8, 2012, 1:51 pm

≫ Next: What is the method to calculate error?

≪ Previous: 3d Core, Error: Unknown function or operator

Hi ,

I am getting this type of error whey i am trying to start simulation.

"Variables property does not include all variables in Xmesh"

Could anybody can give me any solution/ suggestion.

Thank you
Sanjay

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What is the method to calculate error?

April 3, 2013, 6:48 am

≫ Next: Beam excited by a shaker

≪ Previous: Simulation error

I was fooling around with Comsol Multiphysics. I have found very interesting feature included in Comsol. Recently I was testing second harmonic generation module in it.

The error is calculated and plotted with respect to the iteration number. In my sense, if the iteration number increase the error should be decreased (attached pic). But I have found some alternative in this method.

Could you please help me out?

Thanks in advance.

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