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,
Steve
Stephen Seymour, P.E.
Principal Engineer
Seymour Engineering & Consulting Group, LLC
www.seymourecg.com