Why Does MSC Adams Show Increasing Acceleration with Constant Torque?

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Discussion Overview

The discussion revolves around the behavior of a simulated annulus in MSC Adams when a constant torque is applied. Participants explore the relationship between torque, inertia, and acceleration, questioning why the simulation shows increasing acceleration despite theoretical expectations.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant describes a scenario involving an annulus with specific dimensions and a torque applied, expecting acceleration to be calculated as T/I.
  • Another participant questions whether a fixed torque on a fixed inertia would lead to perpetual acceleration.
  • A participant seeks clarification on the conditions under which the equation Torque = inertia times alpha is valid, as typically presented in textbooks.
  • One participant confirms that the expression for acceleration is correct and prompts for the angular velocity after a given time, assuming zero initial velocity.
  • Another participant notes that practical factors such as friction and air resistance would limit angular velocity, suggesting that without these factors modeled, the simulation could show unlimited acceleration.
  • A participant reiterates the expectation of acceleration being T/I and inquires whether the simulation results align with this calculation.

Areas of Agreement / Disagreement

Participants express differing views on the implications of applying constant torque to an object with fixed inertia. There is no consensus on the behavior observed in the simulation versus theoretical expectations.

Contextual Notes

Limitations include the potential omission of factors such as friction and air resistance in the simulation, which may affect the results. The discussion also highlights the need for clarity on the conditions under which the torque-inertia relationship holds.

Who May Find This Useful

Readers interested in dynamics simulations, torque and inertia relationships, and the practical limitations of theoretical models in engineering contexts may find this discussion relevant.

bugatti79
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Hi Guys,
I have a simple annulus of radius 25mm and 15mm of length 50mm where i applieD a torque of T=100000Nmm. Its inertia about its main axis is I=124.9 kgmm2.
Therefore i expect the acceleration to be T/I.
Its not clear how to confirm this answer in Msc Adams because when i set simulation time of 0.1 or 1 sec I always get increasing velocity/acceleration.
What am I missing?

Regards
B
 
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If you apply a fixed value torque to an object with a fixed value polar moment of inertia then it will just keep on accelerating forever ?
 
Then under what conditions does this Torque =inertia times alpha hold that one typically sees in textbooks?
 
Nothing wrong with the expression .

What is angular velocity of object after time t ? Assume zero initial velocity .
 
+1

In practice things like friction, air resistance, strength of materials limit the angular velocity but if you don't model those then the angular velocity is unlimited.
 
bugatti79 said:
Therefore i expect the acceleration to be T/I.
Its not clear how to confirm this answer in Msc Adams because when i set simulation time of 0.1 or 1 sec I always get increasing velocity/acceleration.

Does the acceleration you get in Msc Adams agree with the calculated value?
 

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