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Use and modify prt expressions in idealized part

Experimenter
Experimenter

Hi all, 

 

I am working with the last version of NX12.

I'm looking for a way to use and modify the expressions of my single NX prt file (CAD file) in the associated idealized part, so that I can modify my ipart geometry based on the available CAD expressions without changing the CAD file geometry itself. (E.g. for the investigation of design alternatives, without creating new or copy expressions)

 

 

There is the way to use interpart expressions, but they can't be modified in the idealized part because they are locked.

Furthermore the feature "Master Model Dimension" allows me to modify prt expressions in the ipart, however it also changes the expressions and thus the geometry in the CAD file. I would like to avoid the latter.

 

Is there a way to do that or does it contradict the philosophy of working with the consistent NX simulation model structure?

 

Thank you for yoor support!

 

Regards

7 REPLIES 7

Re: Use and modify prt expressions in idealized part

Phenom
Phenom

Hi,

I'm not clearly know what you intend to do. But, maybe try this.

You should import the expressions of Part in your iPart as interpart expressions and afterwards define new expressions in iPart dealing with the old one with formulas.

Additionally, if you use expressions for geometry (distances or lengths or angles) it's possible to define measurement expressions. - You could measure the body geometry of the original part (in iPart), create a wavelink of original body and then modify the measurements of that wavelink body with synchronous modelling. Scaling or something like that can be done by factors multiplied with the expressions from original part (interpart exp. or re-measurement of length and angles) to get new expressions in iPart for modified iPart wavelink geometry.

 

Other way, define your expressions in excel and use it in your part definition. Build your model completely. If you try to make a design variation, copy complete file set into new directory and modify there the expressions in excel. I'm not sure if the connections use global or relative path definitions. Otherwise, your model in new directory deals with the excel file from original directory.

 

2018-09-07_161845.png

Try it...

 

Does it help you? - Best wishes, Michael

| Production: NX10; Development: VB, TCL/TK, FORTRAN; Testing: NX11 | engelke engineering art GmbH, Germany
| Kudos for good posts! And if my post answers your question, please mark it as an "Accepted Solution".

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Re: Use and modify prt expressions in idealized part

Experimenter
Experimenter

Hi Michael, 

 

thank you for your information so far. 

I try to find a way, so that I don't need to recreate the features I'd like to use. Maybe this example description helps:

Let's say you have a CAD part with fins . There are no features in model history ("dead" part). You start to move the fins by using the Synchronous Modelling feature "Move Face". A designers use the feature to model a first new design. Afterwards in your CAD file you will have the feature "Move Face" and an expression, called "Move_Fin".

 

As a simulation engineer you now want to investigate different designs in the ipart without changing the geometry of the designer. For this you want to use the expression "Move_Fin" and the associated feature from you CAD file and modify it. But you don't want to redefine a feature again, e.g. by creating a new Synchronous Modelling feature "Move Face" again. 

 

Via "Master Model Dimension" in the Ipart (Pre/Post Environment) you can use and modify the features of your CAD file, however changes are also transferred to the CAD file. That is exactly what should be avoided.

 

Best regards

David

Re: Use and modify prt expressions in idealized part

Phenom
Phenom

Fynn,

I'm not clearly understand what you are searching. - I'm an "calculator" no designer Smiley Wink

I made a session with one of my models (really simple part)

1. Define a part

2. define a FEM with iPart , Body selection: none

3. activate iPart and

3.a define a "Linked Body" from my part

3.b deactivate the original body structure

4. activate FEM and select liked Body for FEM

5. mesh Polygon body in FEM

6. define a Simulation in SIM

7. Activate iPart,

7.a Modify the position of two faces with "Synchronous modelling" of linked Body (parent part is unchanged)

8. Update FEM and activate to SIM => Modified Sims...

9. redo 7. - 8. for other feature parameter...

 

SEE pictures

 

Original Part >>>

2018-09-12_091724.png

 

iPart with linked body (unchanged, original part is also visible but congruent) >>>

2018-09-12_091827.png

 

Sim of original geometry >>>2018-09-12_092210.png

 

Modification of linked body , Modification 01 >>>

2018-09-12_091939.png

 

Sim of Modification 01 >>>2018-09-12_092056.png

 

 iPart with modified linked body but other parameters of modification 02 >>>

2018-09-12_092706.png

 

simulation of modification 02 (after update of fem) >>>

2018-09-12_092756.png

 

The original part is still untouched as only the linked body is modified. I do not have to redefine the synchronous modeling feature but I have to modify it.

 

If you want to have both geometries in your simulation you have to define two FEMs with different modifications and group together by using an AFM.

You can save your modifiavtion with starting of renaming at iPart, then FEM and finally SIM.

 

Is it like you wants to do it? - Best wishes, Michael

| Production: NX10; Development: VB, TCL/TK, FORTRAN; Testing: NX11 | engelke engineering art GmbH, Germany
| Kudos for good posts! And if my post answers your question, please mark it as an "Accepted Solution".

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Re: Use and modify prt expressions in idealized part

Experimenter
Experimenter

Hi Michael, 

 

this is not exactly what I mean.

Maybe this helps:

 

1. Define a part with a feature, e.g. extrude and use an expression for this feature

image.png

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

image.png

 

 

 

 

 

 

 

 

 

2. Define an iPart

3. Define a linked body from the CAD part

 

My goal now is to use and modify the expression "Hight" in the ipart, e.g. for investigating the influence of different hights via simulation.

But I don't want to use synchronous technology and new expressions. I want to use the expression "Height" from my CAD part inside the ipart and modify it considering that changes in the ipart have no influence in the CAD model. 

 

Best wishes

David

 

 

 

Re: Use and modify prt expressions in idealized part

Phenom
Phenom

Hi Daniel,

as far as I see it, that's not possible. I believe it's against philosophy of iPart and Part, The function of iPart is leave the Part untouched, but you want to modify the expressions of a part without modifying the part. I think that's not possible.

 

That function you want is some kind of "override" functionality which redefines a feature of a sub part by modifications on higher part level. But you have no access to the features of sub part from higher part in your case, I guess.

 

But now my question, why do you want to keep the original part untouched but want to change it's expressions to get an modified iPart? - Make a copy of you untouched structure into another directory or make a copy of the expressions of your untouched structure and your are able to reset every modification. Of course, copying keeps all structures only manipulate in a certain degree so you can't change your original part in a more complex way without doing it more than ones in every copied structure, I guess (hope I used the proper English Smiley Wink).

 

I assume you have to copy the whole structure including the original part and then you must modify it directly. But, I'm a user like you, I'm not the developer or creator of the software....

Best wishes, Michael

| Production: NX10; Development: VB, TCL/TK, FORTRAN; Testing: NX11 | engelke engineering art GmbH, Germany
| Kudos for good posts! And if my post answers your question, please mark it as an "Accepted Solution".

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Re: Use and modify prt expressions in idealized part

Experimenter
Experimenter

Hi Michael, 

 

of course I could copy my structure, but this is not the consistent way. The traceability will get lost.

There is the possibility to modify the expression of the master part features in the idealized part

image.png

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

But in this case the modifications are also available in the master geometry or take place there.

I hoped that there is a way to break the link between master part and idealized part...

 

But thank you for your support so far.

 

Best wishes

David

Re: Use and modify prt expressions in idealized part

Phenom
Phenom

David,

sorry, but here I'm out. I my case I couldn't activate that functionality for my iPart features whether or not modifying the expressions in Part.

 

I do not understand the correct meaning of that functionality. But, if I define an interpart expression in iPart manually and I set "override" then the interpart expression overrides the expression in Part with the value of iPart directly.

 

See, Defining interpart expression in iPart with "override" >>>

2018-09-18_111658.png<<<

 

Changing it in iPart for Part:10 => 20 mm by means of p39 (defined automatically)>>>>

2018-09-18_113813.png

 <<<

 

This looks like having defined the expression in Part by using an interpart expression from iPart, in a reverse like way.

 

See, Appearance in Part afterwards >>>

2018-09-18_111921.png

 <<<<

 

 

I believe that "Master Model Dimension" does the same in a more convenient way. Here you have the opportunity to change expressions in different parts in one sweep in one higher level object without going into several sub parts to do it there. I assume that's the intention of the functionality. But the expressions which are used in sub part HAVE TO MODIFY sub part geometry.

If you want to modify iPart without modifying Part you have to change the iPart with  "Synchronous modeling". Unfortunately, the capabilities are not the same as in "model a feature directly".

 

That's my point of view as a user (I'm not a developer). Does another one has another one? - Best wishes, Michael

| Production: NX10; Development: VB, TCL/TK, FORTRAN; Testing: NX11 | engelke engineering art GmbH, Germany
| Kudos for good posts! And if my post answers your question, please mark it as an "Accepted Solution".

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