penetration in a really small point is 0,066, is it acceptable?Īs you said Updating Stiffness is the recommended option. You can just type in the magnitude of the interference in the offset parameter in the contact definition.įirst of all of if the max. For example a press fit of a shaft in a hole, where both the shaft and hole were drawn at the same nominal diameter of 10 mm, but the tolerances on the parts call out an interference fit. It's always best to have the CAD match reality as close as possible, but Offset can be a time saver to eliminate doing a very small adjustment in CAD and allow an interference to be created where none existed in the CAD geometry. The solver has a very difficult task getting started when contacts are initially open, and a much easier task when the contacts are initially closed. This is useful when the CAD geometry is perfectly tangent (and also when it is not perfect), but due to discretization in meshing, a tiny gap has been created. The default option provides the fastest solution time, but if you observe excessive penetration in the results, you can change to another option to reduce the penetration and incur a slight increase in solution time.Īdjust to Touch is automatically selecting a value to put into the Offset setting, which results in the contact being closed. There are choices because there are differences in the computational cost of each option. The results are different between Nodal-Normal-Target method and 4 other options. You can't just set the contact to an extremely high normal stiffness because that causes numerical problems for the solver and the solution may not converge. There is a computational cost to do this, so when you don't need it, you can turn it off to get a very slight improvement in solution time. This is generally the best setting, because it allows contacts that have excessive penetration to automatically adjust the stiffness to reduce the penetration. Insert a Contact Tool into the Solution branch then Insert a Penetration plot into the Contact Tool folder to evaluate the magnitude of the penetration on a contour plot.ġ) Updating normal stiffness in each iteration. The goal of nonlinear contact (not bonded) is that the parts should not penetrate by an excessive amount. In future posts, please use the Insert Image button to put your image in the post because ANSYS employees are not permitted to open attachments. I am grateful if someone could advise me if they have some experiences in this regards. For this part also, which option are suitable? Because of initial penetration and some possible errors in positioning load applicator, I selected adjust to touch option, but it was confusing that the results were remarkably different for another option. Now how could be sure that which option should be selected?įor this option also the results are different, if I select Adjust to Touch or Add Offset, No Ramping. The results are different between Nodal-Normal-Target method and 4 other options, and I think that it could be because of Corner-surface contact in a section. When this option is active, does software increase normal stiffness value in each iteration to the default one (1 for frictional and 10 for bonded)? what the difference between update stiffness in each iteration and never? In this model as the attached picture shows, there are some contacts between load applicator as a rigid body and the main structure as a flexible body.ġ) 1) Updating normal stiffness in each iteration: I am modelling a complex friction-less contact and facing some issues that maybe your experience could help me.
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