On 14/02/2019 17:10, Roger Hayter wrote:
T i m wrote:

On Thu, 14 Feb 2019 10:34:38 +0000, (Roger Hayter)
wrote:

snip

from the Wikipedia article and
its references quoted above, people have taken to calling a damper a
mass which acts only on the resonant frequency, not absorbing energy and
thus not reducing Q.

Said mass also damps the oscillation at 'non-resonant' frequencies,
albeit to a lesser degree, just as a person could easier shake a
lighter mass than a heavier one.

snip

No it doesn't! If the system is a long way off resonance both before
and after adding the mass it may reduce the amplitude of vibration, but
not the energy being transferred to the system. So this may or may not
be an advantage; probably not, because it does not alter the applied
excitation force which is presumably not amenable to reduction. But the
practical problem does not generally arise unless the original system
can resonate at the excitation frequency, and the use of mass in this
case is lower the resonant frequency which does reduce the energy stored
to near that being provided by the excitation force, rather than
building up increased oscillation due to stored energy - which is
problem requiring a solution in the first place.


I thought the purpose of the drum weights was to reduce the amplitude of
vibration (in conjunction with the springs) whilst maintaining a balance
between drum movement and whole machine movement (which of course would
happen if you had a solid coupling).


--
Email does not work