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Which connection ?


Which connection ?

It's been so long since I took the Mechanisms class..... I can't remember which connection to use. I have a lever with a spherical pocket in it. Into this pocket is a pin with a fully rounded tip, much smaller than the pocket's sphere. I can't make a ball connection and can't seem to figure out how to use the tangent of it (which is what it really is) as the translation constraint.

To put it another way, imagine trying to construct a joint in which a ball rides within a spherical socket whose radius is 3 times the radius of the ball. The pin is constrained in one axis, but the socket moves in an arc.

Any ideas?


Which connection ?

Hello Peter,

There are two options for your:

1) If using WF5 you can use new ball constraint, which will do exactly
what you want. Caution

thought: it is not supported in large displacement analyses as I recall.

2) If using WF4 or below you can create a spherical coordinate system
within Mechanica. Then

when you create a displacement constraint select the newly created spherical
coordinate system

within the displacement constraint dialog box. You will now be able to
constrain the spherical

degrees of freedom.

Hope this helps,


Stephen Seymour, P.E.

Principal Engineer

Seymour Engineering & Consulting Group, LLC

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