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Problem with Bushing within Hinge Mate in Motion Study

Question asked by Warren Isaacs on Feb 19, 2014
Latest reply on Feb 21, 2014 by Jared Conway

Hi All


I'm trying to use the hinge mate's torsional bushing capability, via the Analysis tab on the hinge mate's properties box, to simulate a torsion spring.


(I'm using this approach, in preference to an actual torsion spring, because the bushing data is held within the mate and so is still present when the assembly in question is re-used in higher level assemblies.  I believe that the same is not true of torsion springs, or indeed any Motion Study feature.  Please correct me if I'm wrong.)


My model comprises two simple flat plates.  One is fixed and the other is hinged off it.  I have a normal force applied to the moving plate.


If I model a torsion spring at the hinge, it resists the applied force and reduces the moving plate's acceleration.


If, instead, I use the torsional stiffness within the hinge's bushing, it has no effect whatsoever, even if I change it's value by several orders of magnitude in either direction.


As a test of bush functionality, If I greatly reduce the hinge's translational stiffness, the hinge appears to disconnect, as though held together by an extension spring, i.e. the separation distance is a funtion of the bush's translational stiffness and the applied force.  (I applied a bit of translation damping to smooth things out for this test, and that worked too.)


So, if translational stiffness acts like an extension spring, shouldn't torsional stiffness act like a torsion spring?  Have I misunderstood what this feature does?







PS  If I apply a torque from within the hinge's torsional settings, it sets the moving plate spinning.  In short, the only feature of the bush which isn't behaving is the torsional stiffness.