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Hydraulic cylinder force


Active member
I have set up a mechanism. A hydraulic jack has to open a door. I have found by trial and error the right amount of force required to open the door.

Is there a way that MDO should do it itself as one can expect from a software?

How to add friction to hinge?

Thanks for reply in advance.


Luis Aguirre

New member

This is kind a late response but maybe it is still a question. The way you figure out the amount of force need it is to put a velocity or acceleration driver in the join and then use a measure to calculate the force exerted in the join by the driver. This force will be the force the hydraulic will need to due the motion prescribe by the driver. This is what is call a inverse dynamics analysis in which the motion is prescribe and the results of the analysis are use to calculate the forces necessary to drive the mechanism.

There is no way I believe to ad friction to the join if you are using any release prior to WFF 2.0. However, I read an email at which PCT is removing the friction functionality again from WFF 2.0 because is given wrong results. The only way to mimic friction without the functionality is to use a force as a function of a computed measure (computed measures only available in WFF 2.0) which will not be as numerical efficient as using the friction load provided with MDX.



Active member

Thanks for reply and the valuable information about MDO.

From your reply I can guess that the retirement of Pro/Mechanica Motion is not that early. It will take another year for MDO to fully replace MECHANICA/MOTION.

As far as my question is concerned what I do is define a force motor and the gravity and mass properties, and then do dynamic analysis with gravity enabled. I get the exact amount of force after few iterations.