What is the damping factor of a cantilever beam in free air?

[Oscar6330]

As part of some research work, I am reading a research paper which has taken damping factor of a cantilever beam c=0.01kg/ ms. With no background in advanced physics, I cannot understand how this assumption has been made. If you could tell me what's the damping factor of a cantilever beam in free air, would really help me understand this concept. Thanks

 

[AlephZero]

It's impossible to say, unless you can give a link to the paper online.

The damping factor will depend on the size and shape of the beam, and it can be VERY sensitive to the way the beam is clamped. (A tiny amount of oil or grease between the beam and the clamp can change the amount of damping by a factor of 10 times).

The best way to find the damping factor for an experimental setup is to measure it.

For a theoretical paper, the damping factor may not be very important, so they may have just picked a number that gives a small amount of damping (say a Q value of 100). Some numerical methods don't work very well if the damping level in the simulation is zero.

 

[nasu]

Is this an AFM cantilever?

 

[Oscar6330]

The paper is titled "Transfer Function Analysis of the Micro Cantilever Used in Atomic Force Microscopy". I cannot upload it here because of IEEE copyright violation (I guess).

The paper discusses an AFM Cantilever. But what I need is a frequency response analysis of a small cantilever beam (dimension 14mm x 3 mm x 0.2mm). One end of cantilever is soldered to a pcb and is in free air. The above mentioned paper gives transfer functions for this analysis but uses damping factor. Currently my analysis is theoretical, so I what value can I assume? Thanks

 

[nasu]

For theoretical formulas, this paper may be useful:
Experimental measurement and model analysis of damping effect
in nanoscale mechanical beam resonators in air
J Applied Physics, author K. Yum

Look it up on Google Scholar.
Also look up papers by J.E.Sader in the same journal, around 1998.