Learning Forum

[Mike Rife]

Not to argue with but you may want to look at changing the allowable penetration instead of the contact stiffness factor. Penalty based contact methods (like Pure Penalty and Augmented Lagrange) require contact penetration, then a force is applied to pull the parts back to a just touching state. But there is a allowable penetration distance [FTOLN]; the default is 10% of the underlying solid element depth. You can run the model as is, then add a load step and change the allowed penetration amount to get a more accurate contact representation. On the contact pair change the Behavior to asymmetric (so only one pair will be created). Then right-click and insert a commands object. The CO should contain the command:ncontact1=_cidnAdd a Load Step to the analysis settings. Insert a command object to the environment (where loads are defined) and enter the following:nrmodif,contact1,4,.01nFTOLN is the fourth real constant of contact elements. So here it is setting it to be 1%. Be sure to set the CO to be applied to the last load step in its Details section. Solve and then compare in post-processing the contact results between the next to last and the last load step times.nMike np.s. here is a screen shot of an simple model example. FTOLN is change to 1% then to 0.1% The use of FTOLN is shown in an model in the Ansys Verification Manual; Mechanical APDL VM number 272 on Hertzian contact. I changed the geometry slightly in order to show a larger contact patch here.nn