Creep Analysis

[Anonymous]

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

[Anonymous]

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.

[John_Holtz]

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.

[Anonymous]

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. 

Thanks in advance.

[John_Holtz]

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?

[Anonymous]

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!! 

[benoit.neu-faber]

Hi @Anonymous 

Did youhad succes defining the CREEP parameters ?

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

Benoit