Nonlinear contacts

- January 5, 2019 at 6:36 am
  
  balsaidi
  Subscriber
  
  Is there any tutorial/ documents that I can go through for setting up nonlinear surface contacts?
  
  Thanks,
  
  Bashir
- January 5, 2019 at 2:22 pm
  
  Sandeep Medikonda
  Ansys Employee
  
  Hi Bashir,
  
  How about this video:
  
  https://www.youtube.com/watch?v=7xg8z4CF1qw
  
  and these resources:
  
  Resource 1
  
  Resource 2
  
  Resource 3
  
  Of course for searching through all the help available, please see this post.
  
  Regards,
  Sandeep
- January 6, 2019 at 9:15 am
  
  balsaidi
  Subscriber
  
  Hello Sandeep,
  
  I am having problem with the generated stresses are way beyond material's yield stress. My problem seems to be due to inappropriate surface contacts' setup. Your suggestion please?
  
  Thanks,
  
  Bashir
- January 6, 2019 at 4:28 pm
  
  peteroznewman
  Subscriber
  
  Hello Balsaidi,
  
  The high maximum stress might be due to a singularity in the model geometry, typically created by a sharp interior corner. The real geometry has a small radius in the corner. If you add that small radius and put several elements around that radius, the stress will be more accurately computed. Here is a video by Simutech group.
  
  https://www.youtube.com/watch?v=ZP9nh4GOkIc
  
  Regards,
  Peter
- January 6, 2019 at 7:30 pm
  
  balsaidi
  Subscriber
  
  Thanks a lot Peter!
  
  Is it possible to exclude that singularity stress (max value) from the legend since it does not reflect the real stress value.
  
  Thanks,
  
  Bsahir
- January 6, 2019 at 7:50 pm
  
  peteroznewman
  Subscriber
  
  If you have a singularity, how do you know what the true stress is and that it is below the ultimate tensile stress for the material?
  
  The proper way to proceed is to add a small radius and put a few elements around the radius and calculate the true stress.
  
  If you have a ductile material, you can leave the sharp interior corner, but add plasticity to the material model. The plasticity in the material will allow plastic strain to relieve the high stress of the singularity. You still need small elements around the sharp corner, but you don't have to edit the geometry.
  
  If you do edit the geometry and put in a radius, you might still find that the true stress exceeds the yield strength of the material, so you then need to add plasticity to the material model.
  
  Regards,
  Peter