Recent content by Rob45

And spark arresters go on exhaust; this power plant undoubtedly needs both.

It appears to OP is averse to reading... [glasses]

Greg, Thanks. The more I think about this, the less likely I think there'll be a problem: I think I'll just try the balloons first, then if necessary, a pistol using just a shotgun primer, no powder. If the mike were to overload, I'd just move the pistol farther from the measuring...

I am going to do a measurement on a larger space than I've tested before - where I've gotten by with a hand-clap - and I'm wondering if there are guidelines for the excitation sound level required? When can I use a large balloon (a friend uses a 36" dia. balloon), for example, and when would...

VR Mobile gives good results; not for levels, of course, but for spectra

And naturally, when you speak of two identical sources (same frequency and level) being in-phase, you mean "at the receiver."

This is an interesting subject. Recently I have been doing quite a lot of damping material tests, to screen candidate materials for a new application. Not having a shaker, I have done this using my trusty hammer. I devised a panel test using the same substrate material & thickness as the...

Yes, reducing the source would be ideal, and I am pursuing that, having already redesigned the engine mounts, which gave a worthwhile improvement. The source in this case btw is a 15L 6-cyl turbocharged Diesel engine making 450 HP and 1550 lb-ft of torque. But the reason for wanting a...

I'm primarily interested in the TMD because of the lack of space to make a significant improvement in the isolator. It already has durabilitiy issues, and softening it would make them worse.

We did in fact run a Transfer Path Analysis showing the cab mounts were major paths for powertrain noise to the driver's ear: mount FRFs were taken, sound and vibration levels were taken in operation. The mount FRFs are available, so I have or can re-take the inertance. This is a...

You could also investigate Lodengraf damping; a paper on this by J.R. Fricke suggests that filling the closed frame with other light materials could also help, including even vermiculite.

Greetings: I have a situation where an isolated vehicle cab structure has poor dynamic stiffness in one direction, at approximately 300 Hz, and therefore has poor isolation. This results in noise at the operator's ear at 300 Hz. Since in this case redesigning the structure is not an...

Pete: I like that presentation; it is simple, covers the bases. It occurs to me that as a safety feature, overtravel stops could be devised to limit travel of the damper mass in the event something changes in the mg set itself, thus preventing a fatigue failure of the TMD? Your presentation...

That is a nice simple explanation, Dr. P!

An interesting paper on Lodengraf damping references work done on aluminum bats; it was published in Sound & Vibration and posted on their website.