Learning Forum

[lis29]

Hi, I'm consistently having trouble getting this sim to converge. I've attached a link to the archive file here. Here's the basic information about the sim:

This is the general sim geometry. 

• The model consists of multiple parts held together by solid body bolts with simplified cylindrical shafts and T-nuts

  • Realistic contacts:

    • Nuts are bonded to bolt shafts with a tiny gap in between

    • Bolt head contacts with gussets are frictional, 0.2 coefficient

    • Nut contact with beam is frictional, 0.2 coefficient

    • Bolt shafts to gusset and beam walls is frictionless (basically the bolt hole)

    • Parts held together by physically modeled bolts have frictional contacts between them if they’re directly connected by a fastener and frictionless otherwise

  • All parts without physically modeled bolts are bonded

• Boundary conditions are two fixed supports where the model is cut off, plus a planar symmetry boundary condition

• 500N force upward

• Fixes attempted to achieve convergence

  • Gradual load stepping from 150N to 500N over 8 steps

    • Total number of steps is 10, first two left without load to allow contacts and bolt pretensions to initialize

  • Increased substeps to 250 initial, 100 minimum, 500 max

  • Removing mesh controls and using a very fine mesh

  • Fixed contacts in contact tool under connections

  • Large deflection on and off

  • Increased Newton-Raphson residual value to 4 and increased mesh density at the NR maxima after a failed solve
  • Used modal analysis to vet contacts
    • No parts flew off and there were no 0 values for modes so this looked fine

Any advice would be greatly appreciated!

[Erik Kostson]

 

 

Hi

Ansys Employees are not allowed to download any files.

Perhaps other forum members might be able to chime in here and help.

 

 

We can though suggest some of our free courses that deal with this type of analysis:

https://innovationspace.ansys.com/product/get-started-with-ansys-mechanical/

https://innovationspace.ansys.com/product/contact-mechanics/

https://innovationspace.ansys.com/product/preloaded-bolted-joint-analysis/

https://innovationspace.ansys.com/product/connecting-parts-together/

https://innovationspace.ansys.com/product/modeling-the-bolt-and-preload/

https://innovationspace.ansys.com/product/connecting-bolts-with-assembly/

https://innovationspace.ansys.com/product/fundamental-topics-in-contact/

All the best

Erik