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How to get residual stress in thermal analysis

Siemens Creator Siemens Creator
Siemens Creator

Hi, I need to obtain the residual stress during a thermal analysis. 

 

I just have the temperature values and how it change along the time on the structure.

I did a transient thermal analysis  but I do not know if I can obtain the residual stress or how to do it. 

 

If someone could help me I would greatly appreciate 

7 REPLIES

Re: How to get residual stress in thermal analysis

Siemens Phenom Siemens Phenom
Siemens Phenom

Do you want residual stress or thermal stress? Residual stress is the stress that remains after removing the loads that generated the stress. Linear analyses assume that after you remove the loads, there is no stress in the body due to the load. You need to do a nonlinear analysis to produce residual stress results.

 

Thermal stress is the stress imparted to a body due to thermal loads. It sounds like you want to produce thermal stress results rather than residual stress results. Linear and nonlinear structural analyses support temperatures as a load. Thermal stress results would be obtained by defining a structural solution that includes temperature loads from the thermal analysis results.

 

Regards,

Mark

 

Mark Lamping

Simulation Product Management

Simulation and Test Solutions

 

Siemens Industry Sector

Siemens Product Lifecycle Management Software Inc.

 

mark.lamping@siemens.com

www.siemens.com/plm

 

Re: How to get residual stress in thermal analysis

Siemens Creator Siemens Creator
Siemens Creator

Thank you Mark

 

Now it is clearer, what I want is residual stress. The body starts at a high temperature and then it decreases.

So I want to obtain the residual stress when the body is at ambient conditions.

Which nonlinear solution do you recommend me to use?

 

Do you have some material o tutorial about this?

 

Regards,

Abdiel Nolasco

Re: How to get residual stress in thermal analysis

Siemens Phenom Siemens Phenom
Siemens Phenom

It still sounds like you want thermal stress - just with a negative delta T.

Re: How to get residual stress in thermal analysis

Siemens Phenom Siemens Phenom
Siemens Phenom

Abdiel,

 

I created a test model for my own benefit using NX 11 and NX Nastran 11. I used Solutions 401 and 601. They both produced similar results. Both of these solutions produce nonlinear stress results and allow for time dependent loading. Solution 401 in NX Nastran 11 has the added benefit of outputting linear, plastic, creep, and thermal strain contributions that lead to the total strain.

 

For both solutions, I ramped a temperature load, using the same temperature for the entire model. I also used a material that has a nonlinear stress-strain curve. The peak temperature was one that would induce plastic strain given the constant coefficient of thermal expansion defined in the material. The last step in the solution returned the temperature back to its ambient state. There is residual strain (and stress) due to the thermal loading causing plastic deformation in the unloaded state. 

 

Attached is my test model, but I suspect you aren't using NX 11 yet. The NX Nastran input files are included too. The solution 401 input file uses some enhancements in 11, but I think the 601 input file would solve in older versions.

 

Regards,

Mark

Re: How to get residual stress in thermal analysis

Siemens Creator Siemens Creator
Siemens Creator

Hello Mark,

 

That's true, I am using NX 10.

And also I have a trouble openning those files because they are from a newer NX version than mine.

Could you help me with that?

 

Regards,

Abdiel.

Re: How to get residual stress in thermal analysis

Siemens Phenom Siemens Phenom
Siemens Phenom

Abdiel,

 

File, Import, Simulation will let you import solver input files. Use that to import the solution 601 input file. Then you will be able to see how I constructed the model. 

 

Regards,

Mark

Re: How to get residual stress in thermal analysis

Siemens Creator Siemens Creator
Siemens Creator
Thank you Mark