Whenever multiple components are to be analyzed in a SOLIDWORKS Simulation study, contact interactions become a concern. SOLIDWORKS Simulation has some great ways of automatically defining contact, and also to the ability to visualize the existing contact interactions.
The Contact Visualization Plot is one method that makes it very easy to identify the contact sets that are being used in the study and the faces they are defined between. What actually happens behind the scenes in any of these contact interactions is that “contact” or “gap” elements are incorporated into the mesh at these locations.
In most practical situations it’s not necessary to be too concerned about the contact elements behind the scenes, which is part of the reason they are not obvious to the end user. But the contact elements are the reason you may have noticed your mesh becomes “out of date” any contact conditions are modified. Consider the rest of this article and companion video for more background information or academic understanding of the contact interactions, than any practical guidelines.
A lesser-known option within the Contact Visualize Plot to “include solver generated contacts” allows the user to gain some insight into the actual contact elements being placed. In the image below you can see a cylinder separated from a plate by a gap. In this example, a bonded contact has been manually enforced across the gap.
It’s a general recommendation not to bond across large gaps, and to treat carefully anytime you do need to bond across a gap. In the image above we can see some evidence of why (in this example the mesh is also fairly coarse to exaggerate the effect) as the face of the cylinder needs to be projected onto the plate to estimate where the contact should occur. Note: The user must click on the “Auto Bonding Surface to Surface” result to see this effect after calculating the solver generated contacts.
A similar recommendation is to use Split Lines to create a separate face for situations such as this. Typically if the two components were touching, a “compatible” or node to node mesh would automatically be enforced at their interface which would ensure the nodes of the mesh on the plate line up with those of the cylinder. This can be approximated somewhat manually by using a Split Line to split the face of the plate, in the area where the cylinder would imprint- as evidenced by the resulting solver-generated contacts with the Split Line below.
In any case, using the Contact Visualization Plot with the option for including solver generated contacts provides the most possible information we can extract from the software about the contact interactions that take place behind the scenes.