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Associativity between Inventor and Simulation - SURFACE BODIES

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Message 1 of 23
MattKurtze5538
1422 Views, 22 Replies

Associativity between Inventor and Simulation - SURFACE BODIES

Hello All

 

I am having issues with the associativity between Simulation 2012 and Inventor 2012 with SURFACE MODELS only.

When you bring a change over from inventor with a solid model all loads and material properties are retained.

However when models containing surface elements are updated all loads and material properties are lost. Is there a work around for this?

I have tried using assemblies with parts containing only surfaces, however Simulation refuses to accept this. It will only accept parts containing surfaces if they are not in assemblies.

I have tried using solid models and midplane meshing the results however the mesh quality at the joins between plates is not up to scratch.

This problem is costing me a lot of time.  I am dealing with complicated thin wall tanks and containers with large numbers of load cases.

 

Thanks

Matt Kurtze

22 REPLIES 22
Message 2 of 23
hupn
in reply to: MattKurtze5538

Hi,

 

How can you add loading for surface only part under Inventor simulation environment? For release 2012, I think that these kind of features are not supported at all, only 3d models are supported for inventor simulation. You may be able to create inventor surface and switch to inventor simulation environment for release 2012, but no loading can be added for the pure surface.

 

hupn

Message 3 of 23

Sorry if I was not clear.

I am talking about autodesk simulation mechanical 2012 (formerly Algor). And the associative transfer of surface 3d models between inventor and it. this package can mesh and load surface features while the simulation component of inventor pro can not (unfortunately).

Cheers

Matt
Message 4 of 23
hupn
in reply to: MattKurtze5538

Hi,

 

Actually you are clear and I understood that you was transferring inventor CAD model to Autodesk Simulation. However; you mentioned that the loading of surface only model get lost after transferring. Then what kind of loadings that you define in Inventor side? How do you define it? That's what I did not quite get.

 

hupn

Message 5 of 23
MattKurtze5538
in reply to: hupn

Ah right.

Ill outline my workflow.

1. Create surface model in Inventor.
2. transfer model into simulation
3. setup simulation and apply boundary conditions and loads.
4. Run simulation.
5. find that stress is too High, need to edit geometry.
6. Change model in inventor
7. Hit transfer to simulation button.

Here is where the problem occurs. If the model contains solid bodies all materials, loads ect are retained after the geometry is updated. If the model container surfaces the properties and loads applied to ALL surfaces in the model are lost (not just those with changed geometry). If the model contained both solids and surfaces, the properties for the solid parts are retained but the those applied the surfaces are lost.

I realize this is complicated.

Thanks

Matt
Message 6 of 23
Joey.X
in reply to: MattKurtze5538

After modifying geometry in Inventor and the geometry part or surface ID are changed, (this usually happens at relative multiple parameter changes or rearrangement in CAD), you will lost the loadings/constraints/material properties which were defined in simulation before since they were specified in previous surface or part ID.

 

 

Jianhui Xie, Ph.D
Principal Engineer
MFG-Digital Simulation
Message 7 of 23
MattKurtze5538
in reply to: Joey.X

I understand this. But when working with surfaces everything is lost, even if no changes are made to the geometry.

Message 8 of 23
Joey.X
in reply to: MattKurtze5538

This is weird and usually should not happen; probably your model is polluted already. Could you try starting from a fresh CAD model, and doing the workflow back and forth to see if this is repeatable?  Another possibility is the software issue which can't handle your specific CAD geometry/feature.

Jianhui Xie, Ph.D
Principal Engineer
MFG-Digital Simulation
Message 9 of 23
MattKurtze5538
in reply to: Joey.X

This is easily reputably with even the simplest surface geometry. Try it. I'm guessing it is an issue with the way inventor talks to simulation re surfaces. I'll post a couple of sample files tomorrow from work
Message 10 of 23
Joey.X
in reply to: MattKurtze5538

it will be good you can post the sample models for the root. Thanks.

Jianhui Xie, Ph.D
Principal Engineer
MFG-Digital Simulation
Message 11 of 23
hupn
in reply to: MattKurtze5538

Hi,

 

That's a clear workflow. I did can re-produce the issue here. Loading and even the material properties get lost. I think it is a software bug when handling the associativity of surface only model. Thanks for the observation. Unfortunately, I do not have a good workaround yet since you mentioned that creating mid-surface way by using 3d thin part has un-satisfied effect. I will post it if I can find a good workaround.

 

hupn 

Message 12 of 23
John_Holtz
in reply to: MattKurtze5538

Hi Matt,

 

You mention that you have a "large number of load cases". If you really mean loads (forces, pressures, etc) and have no geometry changes (other than thickness), then you can do the multiple load cases within Simulation. Each "load case" results in a different set of results, but all within the same analysis.

  • Nodal forces and moments can be assigned to individual load cases, so any number of forces can be in different load cases.
  • For linear static stress, pressures, surface force, and temperatures can all be scaled uniformly by setting the multiplier under the "Setup > Model Setup > Parameters > Multipliers" tab. (did you mention the analysis type?)
  • You could also use different design scenarios to analyze different load cases. For linear static stress, you can also combine different results together (provided the geometry is the same) to create new load cases. See "Help > Autodesk Simulation > Results > Results Environment > Utilities Menu > Load Combinations" for the gory details.

 

But, my guess is that you need to make geometry changes instead of just loads, materials, plate thickness (all of which can be done within Simulation, so no loss of input.) The midplane mesher actually has two different algorithms. If you have not tried both on your solid model, you may have more success with the second algorithm. (As you pointed out, solid models maintain the associativity with the Inventor model.) Try "Mesh > Mesh > 3D Mesh Settings > Midplane > Options > Midplane" and activate (check the box for) "Use junction method".

 

 

If neither of those two suggestions get what you need, then some combination of these tricks may help. Some of these methods require the Simulation model to be multiple parts instead of one part. (I am not sure how Simulation treats surface models and whether you can get multiple parts.)

 

  1. The input under the "Element Definition" and "Material" for selected parts in model A can be saved to a file, and then imported to model B. This would save you from re-entering that data after you create model B. See "Help > Autodesk Simulation > Setting Up and Performing the Analysis > Set Up Analyses > FEA Editor Environment". See the bullet for "Save/Read Part Attributes".
  2. If you know what geometry changes will be made ahead of time, then you may be able to include all of the multiple geometries in the same Inventor file. (Some parts will undoubtedly overlap.) Send all of the parts from Inventor to Simulation. In Simulation, suppress and activate the appropriate parts for each arrangement.
  3. If there are only a few geometry changes, then you can keep everything for the parts that do not change as follows. [3.1] Create a new file name for the Inventor model that has the geometry changes. If you can suppress the parts that have not changed, that would be better.  [3.2] Transfer this new model to Simulation. [3.3] Save the new model. [3.4] Open the original model and suppress the parts that are changing. [3.5] Merge the new model into the original model. Presto, the new parts are in the correct position and the original geometry has all of the input. ("Application button > Merge")
  4. Methods 2 and 3 will keep the loads and part properties. Method 1 will not keep the loads, and I cannot think of a work around for transferring loads from model A to model B.

 

Let us know how it goes.

 



John Holtz, P.E.

Global Product Support
Autodesk, Inc.


If not provided already, be sure to indicate the version of Inventor Nastran you are using!

"The knowledge you seek is at knowledge.autodesk.com" - Confucius 😉
Message 13 of 23
MattKurtze5538
in reply to: John_Holtz

thanks for the replys

John. I have been using all the methods you outlined. They all work to some extent. Except that simulation will not accept an assembly that contains parts with only surfaces, this is something that I tried early on.

I post this mainly in the hope that the 'bug' may be fixed in some future update.

I'll Give an example of the time this costs me.

I'm designing a custom sea container that is constructed of thin folded steel. As I am designing this to the iso standard there are about 20 very diff load cases that need to be tested.

Each load case becomes a separate design senario within the same file.

I set up the geometry and load cases ( about 4-6 hours work). And run

I find that 1 load case fails, and requires an increase in curvature in one plate. Obviously all load cases need to be re-checked incase this change impacts on then.

Now because of this 'bug' I need to apply one of these work arounds to each of the 20 design senarios. This takes almost as long ( if not longer) than the original time it took me to set up the model.

If the system handled surfaces the same as solids all I would need to do was update the model, propagate the changes and re-run simulation.

As all I use the software for is surfaces bodies I feel I am missing out on the best parts of the system.

Regards

Matt
Message 14 of 23
nmt
Advocate
in reply to: MattKurtze5538

I totally agree, I am also having huge issues with plate/shell models as all properties, loads and BC' s are gone after resending a model to Sim.

As for assemblies one way to go is to make a single part file and create one feature for each part. Then Sim. Recognizes each feature as parts.

Another workaround if you need to have an assembly made out of parts as surfaces and perhaps also some solids in the same assy is to make a step file. Then Sim recognizes everything.

/ H. Nilsson

 

Message 15 of 23
MattKurtze5538
in reply to: nmt

Hello

 

Revisiting this issue. 

 

Is Autodesk working on getting the associativity of surfaces working properly? 

 

Its really annoying and costing me a LOT of time.

 

Regards

 

Matt

Message 16 of 23
Joey.X
in reply to: MattKurtze5538

A knowing issue is that the surface based loads get lost if the surface IDs change after CAD parameter changes in either Inventor or simulation (using "fx" icon).  I am not sure if this apply to your case, you can check the related surface IDs change before and after the CAD parameter update. 

Jianhui Xie, Ph.D
Principal Engineer
MFG-Digital Simulation
Message 17 of 23
scudelari
in reply to: Joey.X

Hello Everyone,

 

For what it's worth, I am also an user that depends heavily on the plate simulation on inventor models and this issue described is really annoying. 

 

As it was already stated: I also lose a LOT of time reseting everything.....

 

But not only that. I myself can't understand why the integration between inventor and simulation is so bad.

 

Apart from the data inside simulation that disappears every time the model is refreshed, there are also the following things that are ignored:

 

1- Names of the features are ignored.

2- The colour of the feature is ignored.

 

There was also some other things, but this is just a start...

 

Sincerely!

Message 18 of 23
MattKurtze5538
in reply to: Joey.X

Hello

 

It is not just the surface based loads, but all surface properties.  ie material,thickness,bc's and loads.  Its as if the surface 'parts' are deleted and replaced every time you update the model from within inventor.  Also note that this happes even if the geometry is not changed at all.  Simply hitting send to simulation removes all this data from simulation.

 

This does not happen with solid parts.  Everything works fine then.

 

As I said VERY ANNOYING.

 

In fact I am allmost considering chasing a refund, as I reported this fault about 12 months ago and AD have got no closer to a resolution.  Actually I have not even had a response indicatiing that AD have taken what I have said on board.

 

Regards

 

Matt

Message 19 of 23
John_Holtz
in reply to: MattKurtze5538

Hi Matt and other surface modelers,

 

I am sure it is frustrating, especially since plate models are a better representation of thin solids, so you are doing the right thing by creating and using them, and then you have information lost each time you make a change.

 

I wish that I could, but I cannot give you any news about any upcoming enhancements because

 

a) I do not know what the status is,

 

b) government regulations prevent us from discussing software that is not released. (It has to do with people making purchasing, or renewal, decisions based on what is "supposed" to be in the new software. The problem with "promises" is that any particular feature will be withdrawn from the release if it is not "ready" for release.)

 

In the meantime, here are some options:

 

A) I just discovered that Fusion 2012 has plate element associativity with Simulation Mechanical 2012! In other words, loads, constraints, and part input is retained after changing the model in Fusion!! So before starting the next model, open your surface model in Fusion, make the changes, and export it to Mechanical. Fusion is a CAD app that is shipped (and installed automatically?) with Mechanical. I do not know whether the version we provide has full interop with Inventor or not. I have seen Inventor models that are modified with Fusion pushed back to Inventor, and the features update within Inventor.

 

B) If you prefer to stay strictly with Inventor, the following work-around can be used to keep as much data as possible.

  1. "push" the model in Simulation.
  2. Apply all of the loads, constraints, part properties.
  3. The part properties can be saved to a file as mentioned in a previous post. Select all of the parts > right-click > Save Part Attributes to File.
  4. For each load or constraint that you need to "keep", draw a line on a different surface number. These can be drawn on the same part number, but use a new part number. So if you have one surface constraint, one pressure load, and one surface force, you would draw 3 lines on the new part number. They can be any surface number, such as 1, 2, 3, ....
  5. Select one surface load or constraint that needs to be kept > right-click > Copy.
  6. Select one of the hand drawn line > right-click > Paste. There is the copy of the load that will be kept.
  7. Repeat for the other loads and constraints.
  8. Before running the simulation, suppress the new part with the hand drawn lines. They do not represent anything real to the analysis, just a convenient place to "store" loads and constraints.
  9. Make changes to the model in Inventor.
  10. Push the changes to Simulation.
  11. Select all of the parts > right-click > Paste Attributes from File. Select the files that were saved before. All of the part properties are applied to the "new" model. (This will only work if the part numbers do not change from the original model to the new model.)
  12. The hand drawn part still exists in the "new" model! Unsupress that part.
  13. Select one of the surface loads or constraints > right-click > Copy.
  14. Select where you want the load to be applied to the real parts > right-click > Paste.
  15. You are done. Run the simulation.

Granted. Method B is not the best solution, but hopefully a whole lot better than starting from scratch!

 



John Holtz, P.E.

Global Product Support
Autodesk, Inc.


If not provided already, be sure to indicate the version of Inventor Nastran you are using!

"The knowledge you seek is at knowledge.autodesk.com" - Confucius 😉
Message 20 of 23

Hello All

 

I have found a valid work around to my earlier problem, thanks to all that have helped.

 

1. create surface model as a part

2. create derived parts linked to the above model for all surfaces needing separate identities within simulation

3. create an assembly of the above parts

4. save a close.

5. open the assembly in fusion, DO NOT EDIT OR SAVE

6. push model to simulation, and close fusion.

 

Then if you need to change anything

 

1. save simulation, you dont need to close it

2. re-open the assembly, masterpart ect...

3. make required changes and save + close

4. open in fusion and push to simulation DO NOT EDIT OR SAVE

5. the simulation is updated with full associativity for surfaces, and descriptive part names for simulation parts.

 

Now this extra step is annoying, but less annoying than re-entering all your data.

 

Cheers

 

Matt

 

 

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