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Creep Analysis

Anonymous

Creep Analysis

Anonymous
Not applicable

Hi

 

I want to know how I can do creep analysis using Autodesk Inventor and Nastran? I want to study the creep effects on simply supported pipeline.

 

Thanks you

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Anonymous
Not applicable

Hi @John_Holtz 

 

Is there a sample FEM model that elaborates the procedure to perform Creep analysis in Nastran? It would be great if you could attach it in the comments for reference.

 

Thanks in advance.

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John_Holtz
Autodesk Support
Autodesk Support

Hi all,

 

I am not a creep/viscoelastic expert, but there appears to be two different methods available in the Nastran solver:

  1. Creep has multiple methods for calculating the change in strain over time. The attached example "Inventor Nastran 2020 Users Manual (creep).pdf" is from the Nastran 2020 Users Manual and shows how to setup the model using the Nastran file. As far as I can tell, the Inventor interface does not provide access to the creep laws. (The Nastran Users Manual is available on the "offline help" pages. This link goes to the 2020 version. I'm sure there is a 2021 version, too.)
  2.  Viscoelastic is for calculating the change in stress over time. This material can be accessed from the Inventor interface, but I am not aware of any examples that show how to use it.

In my experience, the biggest problem is finding the material properties. Without that information, you are not going to be able to analyze anything useful.

 



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 😉
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Anonymous
Not applicable

Hi @John_Holtz 

 

I did find the 2021 version of the Users Manual. However, the manual does not clearly mention what the input values represent (Page 322). I have attached a screenshot of the input file script. It would be great if you could help me figure this out. 

 

johanDAX3S_1-1611840463018.png

johanDAX3S_0-1611840243088.png

 

Thanks in advance.

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John_Holtz
Autodesk Support
Autodesk Support

The documentation for the Nastran commands (also known as cards, as in computer punch cards 😄) is online. For example, see the description of the CREEP command.

 

Do you have the material properties that you need to define the creep law? Or are you hoping to get the material properties once you understand the creep laws that are available?

 

 



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 😉

Anonymous
Not applicable

Hi @John_Holtz ,

 

Thank you for the link to the description of the CREEP command. The creep properties for the plastic I am simulating (PEEK-CF30) are not readily available so that is still going to take some effort!! 

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benoit.neu-faber
Advocate
Advocate

Hi @Anonymous 

 

Did youhad succes defining the CREEP parameters ?

If yes, I'd be interested to discuss more in detail with you.

 

Benoit

 

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