## General Mechanical

Topics relate to Mechanical Enterprise, Motion, Additive Print and more

#### How to apply friction onto a pendulum in RBD

• alvincsl
Subscriber

Dear All,

I am trying to run a RBD simulation on a single pendulum. I've created a pendulum model, with the angle of 30 degrees and added standard earth gravity onto the model (+Z Direction) in order to create inertia. However, the results of the pendulum showed that the velocity of the pendulum doesn't slow down and remain at maximum value at every swing.

I tried to apply frictional coefficient on the contacts as well as the joint connections but it's not working. Anyone knows how to resolve this?

Alvin

• peteroznewman
Subscriber
nWhat do you mean contact and joint?nDo you mean you have one model with a joint and another model with contact?nOr do you mean the model has both at the same time? That would be a mistake.nTry using contact only and no joint.n
• Erik Kostson
Ansys Employee
You need only one - just use a cylindrical joint and add friction.nnErikn
• alvincsl
Subscriber
the shaft and the head of the pendulum are joint with only allowing rotation at z-axis. But the ?Connection? branch showed ?contact? between the two surface, hence I thought they are in contact but frictionless. nThe result of the dynamics showed the velocity of the pendulum remain constant throughout the timestep, so I wonder if it?s because I?ve set it to frictionless? What should I do to let the motion of the pendulum decrease over time? n
• alvincsl
Subscriber
@ekostomnthank you. Can you give me more context on the method you mentioned? Do you mean I should change the connection from revolute type to cylindrical? n
• Erik Kostson
Ansys Employee
So use the revolute joint you have, add friction to it, inner and outer radius, and delete the contact.nnSo use only a rev. joint (no contacts).nnFor more info about joints search say in the ansys help manual for:nJoint and frictionnErikn
• alvincsl
Subscriber
ArrayThanks for the reply! It works! nSo I won't be needing any Frictionless Contacts between two faces? Just need a Revolute Joint on those two faces are fine?.
• Erik Kostson
Ansys Employee
Correct- all the best.nnEriknn
• Reza Jafari
Subscriber

Hi, I modeled a suspended pendulum on a structure. revolute joint and frictionless contact is applied. I am going to check in static analysis to see what happened when a gravity force (-y) is applied. I saw the pendulum is rotated in RZ side!