Use of multi-able mass dampers

[747heavy]

Hi Bill,
not sure how much you want/need to dive into the subject.
But maybe you find this interesting:
"next generation" 2CV system integrated into a twin tube strut


http://www.freepatentsonline.com/5392882.pdf


if you don´t mind reading a Thesis on the subject (but it´s for heavy vehicles/trucks), you may want to have a look here:

OPTIMAL SUSPENSION DAMPING AND AXLE VIBRATION ABSORBER
FOR REDUCTION OF DYNAMIC TIRE LOADS

http://www.collectionscanada.gc.ca/obj/ ... Q39479.pdf

[bill shoe]

I appreciate the links, I do plan on checking those out.

Slight change of subject-- I assume high-level kart racing bans TMD? Banning conventional suspension saves a lot of money, but a simple TMD unit could make the cars less violently bouncy for little cost. Perhaps a simple spec TMD at each corner that had a small choice of masses/springs/dampers.

Anyway, enough abstract rambling, I'm actually looking forward to the F1 race this weekend!

[hardingfv32]

Regarding TMD in a kart...

Will the driver sense the oscillations that the TMD is trying to control?

I was in a 125 shifter last week and it seemed very smooth except for the engine vibration.

Brian

[bill shoe]

Regarding TMD in a kart...

Will the driver sense the oscillations that the TMD is trying to control?

I was in a 125 shifter last week and it seemed very smooth except for the engine vibration.

Brian

I suppose it depends on the track surface. A good track made for karts might be extremely smooth.

I once drove an old 1970's era Formula 500 (no suspension whatsoever) on a track that was smooth by normal street car standards but rough by kart standards. The bouncing was severe and I couldn't keep my feet down on the pedals over a few of the bumps.

By the way, I think Evel Knievel actually drove the same F500 car at the Pikes Peak hill climb in the 1970's. An even rougher road and dangerous as well! He was a showman, but he was also a genuine bad-ass.

[SiLo]

I was thinking the other day, if the mass damper had such a nice effect on the car (kerb riding etc) surely someone would of come up with another way to implement it?

I was wondering if it would be possible to do so with fluid, instead of a spring?

Thoughts? Shoot me down if necessary, but at least be humourous about it.

[Neno]

I was thinking the other day, if the mass damper had such a nice effect on the car (kerb riding etc) surely someone would of come up with another way to implement it?

I was wondering if it would be possible to do so with fluid, instead of a spring?

Thoughts? Shoot me down if necessary, but at least be humourous about it.

mass damper was considered as active aero device, who are illegal now. Lotus tried to find another similar way with their front ride height adjuster, but it was also banned. and any other device who's working like active element on the car will be banned. i realy dont think their will be another way.

[RacingManiac]

The Inerter was/is doing the same work is it not? I thought the reactive ride thing that Lotus was doing was more rudimentary though, as a mean to control the pitch, rather than controlling the tire induced oscillation like the inerter...

[DaveW]

The Inerter was/is doing the same work is it not? I thought the reactive ride thing that Lotus was doing was more rudimentary though, as a mean to control the pitch, rather than controlling the tire induced oscillation like the inerter...

When they are used for contact patch load control, there is a fundamental difference between the two. A "Mass Damper" works most efficiently when the suspension springs are rigid, whilst an inerter will do nothing when the suspension is rigid. The Mass Damper is (in a sense) a suspension in its own right, whilst an inerter works to modify the action of a convention suspension.

[Caito]

It could be strategically implemented inside some other device. Let's say, just imagine, you could put them inside the front dampers, and the dampers are put vertical. Then it would be "a secondary use" of the damper, difficult to detect, and can be "easily" argued.

[DaveW]

It could be strategically implemented inside some other device. Let's say, just imagine, you could put them inside the front dampers, and the dampers are put vertical. Then it would be "a secondary use" of the damper, difficult to detect, and can be "easily" argued.

Curiously, that is rather similar our first attempt to take control of an aero car (prior to the Lotus twin chassis concept). We replaced the dampers with rigid links, and attached dynamic absorbers (Mass Dampers) to each upright. The devices were tuned to control the "porpoising" frequency (around 7 Hz), & a young Nigel Mansell drove it around Donington Park. He was quite quick (I recall), but the tyres didn't last long and Nigel complained about the vibration sensed in the steering wheel meant that he couldn't "feel" the car. The idea was dropped.

In restropect, Renault arrived at the right compromise by fitting a single "mass damper" in the nose box, & a relatively conventional rear suspension.

My concern about your proposal is the vibration that is likely to be felt through the steering wheel.

[Tommy Cookers]

Now that is interesting !


Aside, skimming through this thread reminds me that typically off-the-shelf 'absorbers' have intentionally variable rate (eg elastomer) springs to give a general-purpose useful characteristic, and have some inherent damping. This confuses the distinction between pure inertial/mass effects and what would be regarded as damping forces ?