vibration damping

Dear jas:

It depends on the application. The best vibration dampening is not to have any. Beyond this, you have to dissipate the vibration energy, which will involve heating and possibly decay of the deadening material/structure.

There is a solid steel "disc" on the front of the cranskshaft in an IC engine that dampens vibration.

David A. Smith

Cast iron is good for damping for a metal. Specifically it's grey cast iron, I believe.

Cast iron may not have the other properties you need though..

The best vibration damping is done by balancing. (not a material, but a method of material use) If the balancing is correctly done, no other vibration damping is needed since no vibration will be occuring. :)

"N:dlzc D:aol T:com \(dlzc\)" wrote in news:dc0Hf.32282$jR.10399@fed1read01:

That solid steel disc has a carefully tuned rubber layer in it. This is designed to cancel both torsional and bending modes of the crankshaft. Some cars have a seperate bending damper, which makes the tuning process more straightforward, but costs more.

Cheers

Greg Locock

"Spaceman" wrote in news:ht-dnWkng6 _dY3HenZ2dnUVZ snipped-for-privacy@comcast.com:

For the rather small proportion of vibration problems that are balance related this might be true. For all the other vibration problems balancing is no help at all.

Obviously.

Cheers

Greg Locock

All vibration is a balance problem unless the vibration is needed for an operation that needs the vibration to do it's job. :) What vibration problem are you talking about? (c,mon give the full story) :)

"Spaceman" wrote in news: snipped-for-privacy@comcast.com:

Aerodynamic flutter. Gear teeth. Ball bearings. etc etc etc.

| > All vibration is a balance problem unless the vibration is needed | > for an operation that needs the vibration to do it's job. | >:) | > What vibration problem are you talking about? | > (c,mon give the full story) | >:) | >

| | Aerodynamic flutter. Gear teeth. Ball bearings. etc etc etc.

flutter is a tough thing, but an opposing motion internally could balance it in theory, (tough job but not impossible with todays tech.)

gear teeth are vey tough (especially if you need very little play in them) but different tooth designs are actually being tested already and some have improved a lot of such vibration along with making damping devices on the gears (such as plastic) but damping gears does not always work out to well. (especially not in GM plastic gear coverings they tried back in the 1980's) Don't know about what they do now. (they may have a better plastic, have not seen any recently)

Ball bearings can be balanced better. (it is a matter of precision for those.)

Damping materials themselves are not the best idea though for most things (especially not in gearing) damping gears will only allow play that is not wanted to begin with and will cause failure in the dampenin part itself usually. Removing the vibration as best as possible is always better for end results in my book. :)

viscoelastic foam

Dear ms:

I'd go for complete structural isolation surrounded by vacuum. If the Earth has an earthquake, the Moon doesn't feel it. ;>)

David A. Smith

Still very difficult to provide valued judgement = for vibration problems there's just too many variables. Would really need to see plans and application data and if lubrication is involved viscosity and level details.

"Spaceman" wrote in news:vc-dnSHRwugd6HDenZ2dnUVZ snipped-for-privacy@comcast.com:

Really?

Gibberish

Agree, but given the preceeding b/s I hesitate to do so.

No regards

Greg Locock

The only b/s is the lack of problems with my statements that you failed to post at all.

Are you some super smart engineer or something that refuses to show why my statements were "b/s"?

-- James M Driscoll Jr Spaceman

"Spaceman" wrote in news:cMGdnXRBWZIBxHPenZ2dnUVZ snipped-for-privacy@comcast.com:

Yes James, I am a 'super smart engineer', or clue distributor.

I have worked in the field of vibrations for say fourteen of the last twenty years, roughly.

Cheers

Greg Locock

You're not good enough. There are still vibrations! :-)

Cool, What vibration problem did you fix on your last job? :)

"Spaceman" wrote in news:88-dnQBlidCH43PeRVn- snipped-for-privacy@comcast.com:

Torsional vibration of crankshaft: excitation is due to combustion in cylinders, solution is a tuned absorber (bit of rubber and metal)

Road induced shake: solution is to tune the engine mounts and install an appropriately tuned damping mechanisim

Second order vibration in propshaft: solution is to optimise the driveshaft angles.

Gear whine: change gear profile

etc etc

Cheers

Greg Locock

Nice, So you worked for a car company or a company that fixes car companies left over porblems. That is cool. Thanks.

sir, i m designing a tracked robot which will work in close proximitiy of trains, so i want to know the material of both in the robot body and the tracks