Discussion Forum

Hi

this only happens for me if I'm doing structural analysis and I have turned "Physics - Properties - Create Frame ON" AND "Postprocessing - Plot Parameters - Deformed shape on".

In this case COMSOL adds "1" to the deformation scale, in fact with the deformed frame you should not use the "deformed shape" feature.

From my knowledge this is only in the postprocessing plot window the results are not touched

Hope this helps
Ivar

Thanks for the reply. At least I know I'm not the only one seeing this. I don't have the frames you mentioned turned on, but I am doing structural analysis. I'll have to watch out for this in the future. Hopefully fixed in version 4.0

-Jeff

Hi

It will be different in V4, a lot of new features, with the items such as storing mesh build history for simpler re-run, and postprocessing history etc. The pre-pip we were shown at the last automn conference seem finally very good, even if I do not like changes that much, when you have something up running, but finally after a few days at the conference I was very convinced, have heard its on its way on the printers, hope its true ;)

Deformed frames are interesting if you do enhances structural and need to access to the deformed normal and tangential vectors (nx2 ny2, nz2 ...), these are little described in the doc but I like to use them when I must analyse the type of deformation (typically for opto-mechanics)

By the way, since you are doing structural (also my entry point to comsol and were I spend at least half of my time, and I see few on the forum, funnily) how do you treat the rotation in 3D and mix beam and solids ? Or do you not use them together ?
Just as mixing lumped masses and structural ?

Have fun Comsoling
Ivar

Ivar,

I haven't done anything with beam elements yet.

I wonder if people don't ask as many questions on the forum for structural because it involves stuff a person can see and judge intuitively, whereas some of the other fields are kind of invisible and sometimes hard to translate to a mental picture? - Just a thought.

-Jeff

Hi

I beleive its because there are not so many doing structural wit COMSOL, as most common FEM programmes are doing only structural and these engineers already active do not want to switch just for that.

For me COMSOL is still mainly tailored for academics doing multiphysics, and not yet fully for engineers doing advanced structural, allthough everything is in there

My reason for asking is that I find there are many "features" I'm missing, as rotations in 3D, easy torque loads, coupling bulk models mixing shell, beams and 3D structural etc.

I'm doing all this in COMSOL, but I have to write out quite a lot of equations, that take a long time and are not that easy to debug on the small lines and limited length of equations I can eneter into the GUI's, and my models with up to 1MDoF with hundreds of boundaries or more are really too heavy to handle only in the matlab mode.

As I'm regulary sending in suggestions to Support, I'm seeing the Structural module progressing so we sill eventually arrive there too.

Have fun Comsoling
Ivar

Hi Ivar, hi Kevin.

Same problems here. Sadly Version 4 is still not supplied at our server :(
You had the possibility to use V4 yet?

Regards Bertram

Hi

Well current V4.0 in my view is not finished for us for subcontrsacting (my actvity) but very usefull for training to the new environment that is being implemented. I expect quite more in 4.0a, that I have hear is just around the corner, and then for a true "next" release 4.1 hopefully before the conferences this automn, at that point I expect to start to use it for my external work. In the mean time 3.5 is stays as it was, just getting more and more "old fashionned" once I geing used to the new V4 modelling way.
For structural there is a new physics feature for rigid body loads and rotations, very nice, it's implemented in 3D, hopefully in 2D by 4.1, but they have to finsih the documentation of it, it's general and based ont the quaternion theory to get the rotations right in 3D, which is not a trivial task for all cases, Lagrangian and Euler, and also larger deformations.
For the rest there are many nice features, and several in the postprocessing still to be improved to gain time, I run typically 10 simulations or more per day, but today I need still more than a day PER simulation to document it correctly (report the results) and I should be able to document at least 10 models per day to reach an efficiency where I can justify my ROI of uing COMSOL+ CAD ++

Good luck
Ivar