Posted by Rick Denney on August 19, 2001 at 00:13:25:
In Reply to: Re: Re: Re: Vibration, damping, and weight posted by Chuck(G) on August 17, 2001 at 18:13:08:
Look, guys, I'm just a civil engineer. I use and understand about four or five of the dozen or so material characteristics of metals. I'm quite happy to believe that one of those others affects the resonance.
I had assumed that resonance was solely a function of stiffness and mass, but there is a damping characteristic that I have not considered. Just tell me what the parameter is, if you know, because playing with a piece of brass in the basement won't define it and I don't have access to a decent college engineering or materials science library any more.
Of course, metals are not perfectly elastic, or a metal bell would ring indefinitely. So, there must be some plastic process in the metal's matrix. But I'd suspect that with led the problem is that it is too close to its melting point at room temperature, such that it is annealed just sitting there, and so soft that rapping it causes it to yield. Yielding is always a plastic process.
So, which characteristic is it that controls damping?
Rick "who says this is why he didn't want to dump on Mark for using 'damping' in his Monsterweights ad" Denney