Disc Material and Vibration: Which Causes Higher Vibration, Iron or Aluminum?

[Honza]

Hi all,

I´m sorry for my sort of trivial issue to solve. Anyway, imagine two discs rotating at the same rpm. They are the same size - same radius, same thickness. The mass is ideally distributed around the axis, so there is originally no disbalance. One of the disc is made of iron, the second one is aluminum so there is significant difference between both mass. Each disc is placed on ideal shaft in bearings. I put exactly the same weight on the same radius and i measure vibration in radial direction. What´s the result? Do i measure higher/lower vibration on iron or aluminum disc?

Thanks

 

[physwizard]

why do you expect vibration? the discs may slow down but why would they vibrate?

 

[Honza]

Sorry for my terrible explanation. It´s steady state situation. Both discs are spinning with the same weight attached at the constant angular velocity.