Concrete non linear material properties

Anonymous

Concrete non linear material properties

Anonymous
Not applicable

Dear,

 

I'm a student at the University of Ghent, Belgium.

 

For my Masterthesis i'm modeling a twin I-girder bridge in Inventor Nastran.

 

Everything is working fine but i don't know how to define non linear material properties of concrete?

 

Could someone please help me with this? 

 

Kind regards 

Arthur Decuypere 

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Replies (4)

Roelof.Feijen
Advisor
Advisor

 

Hello Arthur,

 

I do not have any experience with concrete. 
The interface of Inventor Nastran has no option to specify the concrete material model.

In the past this option was available but somehow they removed it from te interface. Not sure why.

You can edit your Nastran file (.nas) in the Nastran Editor and add the concrete material specification manually. See this link. 
You need to get familiar with the way the Nastran file is written. 
Sometimes I use Inventor Nastran to setup 99% of the analysis, let is generate the Nastran file. 
Edit the Nastran file in the Nastran editor en solve it there. You can also edit the Nastran file in Inventor Nastran, but I prefer the Nastran editor. Hope this helps. 

Roelof Feijen

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John_Holtz
Autodesk Support
Autodesk Support

Hi Arthur,

 

What material properties do you have for the concrete? That might help us to know what options you have for entering them into the software.

 

Roelof suggested the CONCRETE material, but it has issues with converging. You can try it, but the analysis may not solve.



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

Dear,

 

I have the mean compressive strength at 28 days of the concrete. 

I calculated the values according to eurocode EN1992-1-1,  to represent the stress strain curve of concrete.

So now I wonder how I can insert these values into Inventor Nastran. 

Because I think if I use the non linear plastic material properties as shown in the image, that compressive strength will be seen as tensile strength? 

Schermafbeelding 2020-05-13 om 16.02.17.pngSchermafbeelding 2020-05-13 om 16.14.27.png

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John_Holtz
Autodesk Support
Autodesk Support

Hi @Anonymous 

 

You are correct that the plastic (and elasto-plastic) materials use the same properties for tension and compression, so that will not work for you situation (unless the model only experiences compression, or the tension is below the permissible maximum tensile strength).

 

Autodesk Nastran does not have a material model that functions and permits different tension and compression capabilities. The best that you can do currently is to run the analysis and use the results that are less than the allowable tension and compression limits. (In other words, the results up to the allowable tension limit or up to the allowable compression limit are correct. What happens beyond those limits cannot be calculated.)



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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