Cold Working Ansys: Compressive Residual Stresses Around Holes

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Discussion Overview

The discussion revolves around simulating compressive residual stresses around holes in an aluminum plate using Ansys. Participants explore methods for modeling and analyzing the effects of cold working, particularly focusing on the steps involved in setting up the simulation and addressing issues related to displacement and stress removal.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant seeks guidance on inducing compressive residual stresses around a hole in Ansys.
  • Another participant suggests that the process can be simulated by modeling the cold expansion of the hole and emphasizes the importance of material properties and mesh quality.
  • A participant describes their approach of using cylindrical coordinates, displacing nodes around the hole, and then removing the displacement to analyze results, but encounters issues with obtaining results in the second step.
  • Questions arise regarding the method of removing displacement and whether the analysis was conducted in multiple load steps.
  • One participant admits to improperly deleting displacement data instead of removing stresses and seeks clarification on the correct procedure.
  • Another participant advises that the removal of displacement should be gradual and emphasizes that stress should not be removed directly, as it can lead to non-homogeneous spring back and affect residual stress outcomes.
  • A later reply indicates that the suggested methodology was helpful and resulted in achieving desired results.

Areas of Agreement / Disagreement

Participants generally agree on the need for a proper methodology in simulating residual stresses, but there are differing views on the correct approach to removing displacement and stresses, indicating that the discussion remains somewhat unresolved.

Contextual Notes

Limitations include potential misunderstandings regarding the load steps in the simulation process and the implications of improperly handling displacement and stress removal.

moazzam.habib
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I have got a metal plate of aluminium. I want to put compressive residual stresses around the hole in Ansys. Can somebody guide me how can i do in ansys?

any help will be appreciated.

moazzam habib
university of hertfordshire
united kingdom
 
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The process of inducing the residual stress(ball drifting etc)can be simulated in ansys.You need to have the tested material property and a proper mesh (especially near the area of interest) to do it. I assume that you are referring to cold expansion of the hole.The drifting of the tool into the hole and the retrieval of the tool back has to be simulated .The resulting stress after the tool leaves the contact with the plate is the residual stress.
 
Hi, meetsarivastan

you'r right! I am doing the same procedure as you've guessed! I am working on a non linear model! What I am doing so far is:
model the geometry and change the sys to cylincerical co-ordinates. [ick the nodes around the hole, displace them and then rotate all of the to bring into active co-ordinate system. solve it and get the silution. This was the 1st step. in the second step i remove the uX displacement. But the problem is, i don't get any result in 2nd step. It shows no deformation or stress in the entire region. can you guide me for this particular problem?

thanks in advance.
 
Can you explain how you have removed the displacement?have you carried the analysis in two load steps?

The following journal papers may also be of use to you :
1.The residual stress intensity factors for cold worked cracked holes - P.M.G.P.Moreira et al
2.Effect of residual stress around cold worked holes on fracture under superimposed mechanical loads - Pavier .J et al
 
I just simply deleted the displacement data from the nodes by picking them after getting the solution. I know that's not the procedure. I have to remove the stresses not displacement. But I do not know how can I remove the stresses?
 
P.s it isn't 2 load steps. I am sloving and without finishing doing the next steps.
 
Make the application of displacement as the first load step and the removal of the displacement as the second load step.Do the removal process also gradually (by using more sub steps).
your methodology is correct and you should not remove stress.The deletion of the displacement boundary condition causes non homogeneous spring back and hence residual stress.
 
thank you meetsarivastan! that was really helpfull! I am getting my desired results now! Thanks again!
 

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