We start that process by asking six questions:

For more types of vibration dampers in transmission lines information, please contact us. We will provide professional answers.

1. Is the component stationary or mobile?

Stationary and mobile components demand distinct approaches. Stationary components benefit from a simple mounting system, where a vibration-isolating material is sandwiched between two metal pieces. This straightforward solution can enhance machining precision, prolong product lifespan, reduce maintenance, and is cost-effective.

On the other hand, mobile devices, especially off-highway vehicles and marine applications, face more frequent vibrations. If the isolating rubber fails, would the unit stay intact or separate from the system? This is why selecting a "safetied" mount is essential. Also, consider the diverse external conditions the mobile devices will encounter. Various mounts are tailored to address these specific needs, requiring careful selection to meet user-specific criteria.

2. What is the weight of the component we are isolating?

The weight of the component significantly influences the choice of materials for isolation. It’s crucial to consider static and dynamic loading on the isolation system. Can the isolators handle the inertial forces? Incorrect materials often fail under wrong pound-force per square inch (PSI) conditions.

Consult a qualified engineer from RPM for insights on weight-related issues. Contact us for expert guidance.

3. How many mounting points will you have?

The number of mounting points is crucial as it relates to both weight distribution and motion control. The weight of the component in relation to the number of mounting points determines the minimum material strength. The number of mounting points can substantially influence the design.

4. Center of gravity details

Determining the center of gravity is essential for effective vibration isolation. Understanding its location in relation to the isolators gives an accurate picture of the system dynamics, informing isolator design considerations. Offset centers of gravity can result in varied loads on each isolator.

5. What is the vibration source we are isolating?

Different vibration sources such as fans, motors, and pumps require unique isolation approaches due to their varying frequencies and allowable motion. Specific materials and mounting systems are necessary for each source.

6. What are the environmental conditions?

Elastomers respond differently under various environmental conditions. These environmental factors are crucial in determining which materials will function best for a given application.

Tuned Vibration Dampers- Optimal parameters and ...

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Tuned Vibration Dampers- Optimal parameters and general discussion

Tuned Vibration Dampers- Optimal parameters and general discussion

FeX32

(Mechanical)

(OP)

24 Jan 18 03:57

I have a general question for the experts here who have tuned or designed engine/crankshaft tuned vibration dampers before (preferably the kind on the C/S nose). I have been reading through some of the info on the forum here in this regard and am wondering if someone has some good insight about a comment in this old thread.

Quote (ivymike)

"I quit reading it after the author claimed that his dampener both absorbed less power and also provided greater dampening. I don't believe the two results are mutually compatible; greater dampening would also imply greater energy absorption. Seven years ago, when I last did TV analysis on a regular basis, that result was not uncommon. The most effective damper commonly did not dissipate the most heat – they often dissipated less heat than those which were less effective at reducing vibrations. It's a bit fuzzy now, but I think that result was common with elastomeric or viscoelastic dampers, and not so much with viscous ones."

This comment about the TVD that were the most effective being the ones that didn't necessarily dissipate the most energy is counter-intuitive to an extent. I have done a decent amount of theoretical linear TVD work before and can know from that there is optimal damping that reduces the effectiveness at the frequency of interest but broadens its working range so that it doesn't create two ineffective regions below and above this frequency of interest. Maybe he is just referring to the damping and not energy - is it possible to look at this from strictly an energy point of view?

Any comments are appreciated.
Thank you.
FeX32

RE: Tuned Vibration Dampers- Optimal parameters and general discussion

GregLocock

(Automotive)

24 Jan 18 10:38

It all depends on what you mean.

Imagine a simple 2DOF system. If the masses are very roughly equal, then the attenuation at the initial resonance is excellent and does not rely on damping. Away from that speed, yes, damping is important.

Cheers,
Greg Locock

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Additional reading:
Everything You Need To Know To Find The Best is Glass an Insulator of Electricity

RE: Tuned Vibration Dampers- Optimal parameters and general discussion

FeX32

(Mechanical)

(OP)

24 Jan 18 23:44

Thanks, Greg. I know what you mean - basically, I am trying to understand more about what detail to look for in TVD development and how important damping is from an overall performance perspective. Is there a key analysis you would typically conduct?

RE: Tuned Vibration Dampers- Optimal parameters and general discussion

GregLocock

(Automotive)

25 Jan 18 00:07

To be honest, I just order a selection of geometries and rubbers the supplier recommends for the given crankshaft modes we don't like (bending and torsion), and then either measure TVs or select them by ear. I don’t remember actually measuring anything for bending, but I suppose crank block acceleration would do. Bending I usually tune by ear.

Cheers,
Greg Locock

RE: Tuned Vibration Dampers- Optimal parameters and general discussion

FeX32

(Mechanical)

(OP)

25 Jan 18 00:39

Thank you, Greg. I didn't realize that these rubber TVDs are also utilized for the bending mode as well. When tuning by ear – do you think this could also be done by noise analysis? Also, I assume you are testing on engine dyno? And do you think there is a method to verify performance without having an engine to test on? Like if you were targeting a certain mode and frequency, could you test the TVD separately from the engine to correlate potential performance? Thanks again.

RE: Tuned Vibration Dampers- Optimal parameters and general discussion

GregLocock

(Automotive)

25 Jan 18 04:53

"Also, I assume you are testing on engine dyno?" No, usually in car.

"And do you think there is a method to verify performance without having an engine to test on? Like if you were targeting a certain mode and frequency, could you test the TVD separately from the engine to correlate potential performance?" In the more general case of tuning tuned absorbers, we found that hammer testing the absorber bolted to a large lump of concrete was a remarkably poor indicator of its performance in the car. I don't know why.

"When tuning by ear - do you think this could also be done by noise analysis?" You should see a change in noise or vibration at the bending frequency. Normally, I’m a fan of objective analysis, but in the case of crankshaft bending modes, the right tune stands out.

Cheers,
Greg Locock

RE: Tuned Vibration Dampers- Optimal parameters and general discussion

FeX32

(Mechanical)

(OP)

26 Jan 18 01:30

The bending mode is not usually an objective problem; it mainly causes poor sound quality. Not every car gets a bending absorber. I'd be a bit surprised if most cars did not have a TV damper. While they are primarily there to prevent crankshaft fatigue, they also improve noise quality. I think your proposed torsional test is the best option for a rig test, but if you're going to go through all that trouble, why not just stick it on the engine?

Cheers,
Greg Locock

RE: Tuned Vibration Dampers- Optimal parameters and general discussion

FeX32

(Mechanical)

(OP)

26 Jan 18 03:36

Thank you again. "Not every car gets a bending absorber." So are there absorbers available that are only for this mode, or are torsional dampers tuned to both? "Your proposed torsional test is the best hope for a rig test, but if you’re going to all that trouble, why not just stick it on the engine?" I understand what you mean here, but if you don't have the engine to test with (say it's not built yet), then there must be a method to propose an optimal TVD while only having a simulation with proposed crank geometry. What do you guys usually use for simulations of this nature?

RE: Tuned Vibration Dampers- Optimal parameters and general discussion

GregLocock

(Automotive)

26 Jan 18 07:23

I don't do NVH anymore, I don’t know what they use.

In the eighties, we used a separate little harmonic damper for bending. It bolted onto the crank nose inside the pulley. However, in the nineties, Ford Australia started using a design of TV damper in which the rubber was profiled in side view, which meant that for a given TV tune, you could vary the bending tune. Very clever.

Cheers,
Greg Locock

RE: Tuned Vibration Dampers- Optimal parameters and general discussion

GregLocock

(Automotive)

26 Jan 18 08:00

I've just employed a poorly trained CAD guy to draw a TV damper. Changing the nominated radius to infinity or even negative alters the bending frequency of the damper while having little effect on the torsional frequency.

Cheers,
Greg Locock

RE: Tuned Vibration Dampers- Optimal parameters and general discussion

FeX32

(Mechanical)

(OP)

27 Jan 18 16:21

That's some great info, Greg. Thanks again. That is a clever idea using the curvature to affect the bending mode. So I can conclude that if we tune the torsional mode out without considering the bending mode, it can be a bad thing? I would assume so. Do you remember what kind of damping factors you were using? I assume the damping of these devices is just as if not more important than adjusting the natural frequency. Is this generally correct?

RE: Tuned Vibration Dampers- Optimal parameters and general discussion

GregLocock

(Automotive)

27 Jan 18 21:34

Yes, tuning for frequency is much more important than the damping. In the more general case of tuned absorbers, too much damping is often a bad thing.

Cheers,
Greg Locock

I'd guess we were around 60-80 Shore A, whatever damping that gives. I wouldn't worry about the bending mode; nobody used to. On an I6, it is audible, but not on an I4, generally. On the LT5 Corvette engine, which had a crank nose mounted gear type oil pump, the bending mode was strong enough to damage the pump, so that got a bending damper.

Yes, tuning for frequency is much more important than the damping. In the more general case of tuned absorbers, too much damping is often a bad thing.

Cheers,
Greg Locock

RE: Tuned Vibration Dampers- Optimal parameters and general discussion

FeX32

(Mechanical)

(OP)

28 Jan 18 16:33

Thanks, Greg. "In the general case of tuned absorbers, too much damping is often a bad thing." Can you