MK belldeal-actuallly switchin" to Natural Frequency

[John Crozier]

Me thinks there's a fine line betwixt anile, and cautious.
Actually, it's not all that fine......

  ----- Original Message ----- 
  From: Gray E Fowler 
  To: discussion at nsrca.org 
  Sent: Thursday, February 03, 2005 1:16 PM
  Subject: MK belldeal-actuallly switchin" to Natural Frequency



  "Agree w/ John about using foam as a vibration damper. Also, someone much wiser than me pointed out that whatever is installed should NOT be halfway, 1/4 way, or any reasonable fraction of the pushrod length because these may end up as stationary nodes in the vibrating rod, and end up doing no good. 
  Rick" 


  Rick 

  Could happen but consider this.....The resonance or flutter results from a combination of factors. One is the modulus of the item and one is the mass. In the case of our push rod scenario, the cf rod has a consistent stiffness the length of the rod, so that is constant, but the longer the rod the easier it is to buckle. A full length rod has a certain mass and a half length rod (foam in the middle) has half that mass. The apparent stiffness of the half rod is greater and the mass is less therefore what make a full length rod resonate most likely will not make the half rod do the same. In addition, having the rod in contact with the foam dampens the resonance, as opposed to a situation where the rod is hard fastened, and therfore sets up a new set of resonance factor based on the mass and modulus again. 

  Hopefully this makes sense...I absorbed this primitive knowledge hanging around true stress weenies...    



  Gray Fowler
  Principal Chemical Engineer
  Composites Engineering
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