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How do I link one motion to another as if they were connected via an ideal, massless gear

Question asked by Mats Lindqvist on Sep 27, 2017
Latest reply on Sep 27, 2017 by Mats Lindqvist

I'm setting up a motion analysis and I have an example where I want to study the coasting down from full speed to zero as the power is turned off. The rotor of the electric motor has some inertia, but most of the friction (that slows down the machine) comes from the internal components. I want to link the rotor axis to the internal moving parts, so as to simulate the coasting down from full speed to zero, and then the internal components will act as a "brake" that slows down the motor. To accomplish this I want to create an idealized gear, so as to link the motor axis rotation to the machine's input axis rotation. In reality this is a belt drive, but I do not need to model that on a detailed level. I just want to link those DOF's.


This machine is suspended on springs, and runs at supercritical speed, i.e. above the three lowest eigenfrequencies (in-plane translation/rotation)  I want to model what happens as the power is turned off, and you pass through the critical frequencies. During startup this is not a problem since this happens quickly, but when shutting off power, there is no "brake" to slow down the machine, and we will pass the critical frequencies slowly.