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What is the difference between suppressing a joint and making it free. Is there a reason you would use one or the other? Does either give different behaviors or is it more of a different way to do the same thing?
Hi Clayton,
Are you modeling in Inspire Structures or Inspire Motion? The reason for the question is that there are additional reasons for using free joints when doing motion analysis.
When a joint is suppressed, it is completely deactivated from the simulation. The biggest use case for suppressing is in debugging and doing what-if scenarios (for example, different motion inputs).
When joint is set to Free, it can serve a few different purposes - 1) It can be used for debugging, similar to what suppress does, except the definition of the joint is still active in the simulation. So, it is active, but is not constraining any DOF (useful before suppress became available as a feature. 2) Free joints can be used to help define Couplers (Inspire Motion). When creating a coupler, "At free joints" is an option. If there is, for example, a free joint defined at the interface where the two gear teeth physically make contact, and you use the "At free joints' option, the ratio for the coupler is auto-calculated using the free joint. 3) Free joints can be used to define Contacts (Inspire Motion) quickly. For example, if you have a free joint defined between the near-touching edges of a cam and follower, using the "At free joints" filter on the Contacts guidebar can help you quickly identify the two parts as a "Contact" pair.
Regards,
Scott Z
I'm using the joint in structures. It's not clear what options for joints only work in motion and have no effect in structures. Example I have a cylinder in a hole, diameters size for size. I have used contacts in structures to give a sliding contact but I believe this is contact without friction. So I decided to create a cylindrical joint between the cylinder and hole (instead of the contact) and then make the joint rigid so I can turn on friction but I am not sure if the friction properties will be used in a structures analysis.
Is there clear information on joints to indicate what all the options do and if they are for structures and/or motion. The Inspire help is a bit vague here.
Clayton
Friction in joints is only applicable to motion, as static FEA in Inspire is not including friction.
I'm attaching a document used to show the different treatment of joints in motion. I realize you are doing structures, but the doc will help you understand what some of the various switches are from the motion side. Much of the HELP on Joints is covering motion joints, because the optional features for joints are primarily there for motion.
