Regular Connections

Regular connections can be used to define contact-based connections between parts in an assembly.

In SimSolid, connections are determined using proximity criteria. Two tolerances are used to establish part proximity: absolute gap tolerance and absolute penetration tolerance. If the parts are close enough to meet the gap tolerance criterion, or have a slight inter-penetration meeting the penetration tolerance criterion, then these parts are considered to be in contact, and a connection is established.
Figure 1.
SimSolid is very tolerant of part geometry imperfections. Small gaps or overlaps between parts can be easily accommodated. Using only 3 parameters (gap tolerance, penetration tolerance and connection resolution), SimSolid creates a proprietary connection entity between each part in the assembly. Then, with each solution pass, the traction forces in the connection are measured and the solution is locally adjusted to minimize solution errors in the boundaries. In this way an accurate solution is obtained on the real, not merged, geometry.
Note: While these contacts are permitted, and loads will be transmitted through the joints, it is not a good practice to have excessive overlap in areas where stress detail is desired.
Tip: A best practice is to set the tolerances just large enough to cover the intended gap or overlap. Be careful to not set the values too large as this will over stiffen the model.

Connection Resolution

Connection resolution defines the mathematical completeness of the connection entity. Three settings are possible: Normal, Increased, and High. While details of the equations are not important to the user, you will need to be aware of regions where connections may not be adequately defined.

In SimSolid, connections resolution is visualized by icon density

Figure 2.
Tip: Make sure there is adequate coverage in thin or curved regions. Look at the icon density and increase it locally as required. Care must be taken that connections don’t create hinges (allow rotation between parts). This will cause structural instability during the solution process.

Fastener Connections

Regular connections around bolts, nuts and washers are grouped under fastener connections.