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ptc-46314451-Visitor
1-Visitor
February 11, 2018
Question

Mechanism Dynamics

  • February 11, 2018
  • 1 reply
  • 2261 views

Hi --

I have been using PTC since version 2001. I purchased the MDO (Mechanism Dynamics Option) in  2012, and have used it extensively, with some questions that I managed to get around. I am now trying to check the program for issues that I noticed in the past. I am attaching a JPEG of a simple model. It is simply a rotating block on a shaft, with the shaft spinning in a hole in the large grounded block on the right. I am trying to measure the forces and moments at the connection where the shaft fits into the grounded block. Using a "pin" connection when assembling the rotating body to the grounded block, the program insists on showing the pin connection at the joint between the rotating block and its shaft, as evidenced by the force arrow shown! The force and moment numbers are correct for a joint in this position, but how do I get the connection in the location I want?

 

I am using MDO primarily for balancing rotating mechanisms. I just want to better understand the program, to be confident in my answers.

 

Thanks for any help.

 

 

 

 

1 reply

P
ptc-46314451-VisitorAuthor
1-Visitor
February 13, 2018

I just tried assembling a plain shaft into the hole in the block. The pin connection is placed at the end of the shaft -- not where the two are connected. I must be doing something wrong.

T
TomD.inPDX17-Peridot
17-Peridot
February 14, 2018

Something is definitely amiss, but probably your model is at fault.

 

The block that is fixed to the shaft should be a hard set of constraints, not mechanism.

 

The pin option has the ability to set a axial relationship; an angle relationship, and a depth relationship.

That should be sufficient to manage this type of mechanism relationship.

 

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