Ansys FEA Help required

[aymena22]

Hello,

I am new to the forum and require assistance with a simulation.

I am trying to determine how material selection can change the characteristics of a wrench (spanner.
I am analysing the contact between a bolt head and a wrench, currently I have simplified the analysis to two cylinders of different diameter in contact in order to validate the theory before moving on to my analysis.

I have found Hertz contact theory allowing me to find the maximum contact pressure between two cylinders however I am having problems recreating this on Ansys.

I have used the Solution > contact tool > Pressure to find the pressure at the contact region however it is very different to my theoretical calculations.

Calculated Maximum Contact Pressure – 264.5 MPa
Ansys Maximum Pressure (from contact region) – 10.7 MPa

ANSYS SETUP
One cylinder is FIXED and the other can only move in the X direction
Force of -500N applied
Large deflection is OFF
Contact has been set to BONDED and ASYMMETRIC
Material selection has been left as Structural Steel
Mesh refinement is adequate
All results are displaying AVERAGED

I have also tried using a Frictionless Contact and the analysis failed.
Could anyone help with the setup as I am unable to get this working and would greatly appreciate any help.

Thanks in advance.

 

[rickfischer51]

This needs to be done with frictionless contact. Bonded contact is meaningless in this context. Set the contact to frictionless, symmetric, weak springs on, and no update of contact stiffness. Start with pure penalty method. Your mesh needs to be fine, and force the mesher to keep midside nodes. Avoid tri or tet elements near the contact area. Try applying a deflection instead of a force.

 

[aymena22]

Hi,

Thank you for your reply.

 

[rickfischer51]

Something happened to this thread. Posts since Christmas are gone. Anyway, in response to the missing stuff, Hertz contact between cylinders is trivial. See the attachment. Play with the mesh density, and refine it until the peak stress stabilizes.

 

[aymena22]

Hi,

Thanks for the reply. I am not sure what has happened to the previous posts, they have disappeared for some reason.

Are you able to save that file in a different format. I cannot open it as it says it was saved using a future version of Ansys.

Thanks very much

 

[rickfischer51]

What version of Ansys are you using?