The modal seperation chart is used to ensure the various modes (natural frequencies) of the the various subsystems (powertrain, chassis, body, etc.) are sufficiently seperated, so as to avoid overlapping responses when excited by inputs due to combustion, road vibration, etc. We also overlay...
Greg,
FWIW, I worked briefly on this. The order transformation can help explain how resonances in mount vibration can be related to crankshaft torsion & bending. It's extremely difficult to measure unless one "demodulates" the entire waterfall, as Turgay did in his paper. His references give...
This "might" help...for a theoretical assessment with ~ 10 data points see
"Variability of Interior noise levels in passenger cars"
by L.A. Wood and C.A. Joachim
ImechE 1984 paper C136/84
We're assuming that good gears make noise because the tolerances on the supporting structures (carriers, etc.) are too big, causing poor alignment. Problem is, we haven't been able to find out which assembly parameter(s) are creating the (presumed) mis-alignment.
We can't actually measure the...
We are working on an automotive transmission, and there is insufficient clearance between the box & the chassis for acoustic treatment (as well as durability issues in operating environment).
Yes it seems the resonance is internal to the box...working with FEA to understand it.
Fc for the case...
I'm working on a cast aluminum gearbox that has high frequency airborne gear whine. (throughout ~500-900Hz, with a few peaks). We checked for resonances on the case, but they don't line up with noise peaks. Adding nice ribs has not helped. We can't use a sound blanket or other acoustic...
