Representing a ball joint with friction in MDO

[SteveBarnhart]

Sim Gurus,

Please help me understand how MDO calculates frictional forces in WF2.

I have defined a three-pin connection mechanism to represent a ball joint since the MDX ball connection does not allow definition of limits or friction. I can define friction on a pin connection, but I feel like I need to define a pre-load to represent the joint stiffness of the assembled, but otherwise unloaded, joint. Is there a way to define this initial stiffness? Does MDX use F=µN to calculate frictional forces or does it calculate as a function of velocity?

Are there any upcoming improvements to WF that will make this possible? Am I reaching beyond the capabilities of Pro/E for this one? Ok, that's enough questions for a Tuesday.

Thanks in advance!
Steve Barnhart

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[randyspeed]

Steve,

Friction in MDO is calculated using F=µN so you have to have a normal force to get any friction force.

Damping is a function of velocity and is sort of a friction when things are moving. However, damping is not friction. Damping works to slow velocity and you will have a resulting damping force build up.

MDO allows you to specify a "static" friction coefficient and a "dynamic" friction coefficient. The static friction coefficient is the kind of friction required to "break out" from a rest condition and is due to molecules sticking to each other.

Randy Speed
President, CEO
Speed Consulting, LLC
www.speedconsulting.com