Can strong plastics be used as an alternative to leaf springs?

[kannanraja]

to make leaf spring we can use any plastic materials ? what are strong plastics? please find it friends

 

[Doug Huffman]

Kevlar is strong in tension. Layered with a plastic strong in compression makes a good plastic spring - though commonly expressed as a bow strung for shooting arrows. Similar shape, same technology.

 

[Baluncore]

Welcome to PF.

please find it friends

You cannot expect the members of PF to search for a new special spring material just because you hate steel.
If you have a new material or technology then please let us know. We will review your suggestion.

 

[dragoneyes001]

what use would the leaf springs have? if its automotive i'd be surprised that the engineers creating super-cars would not have already tested the longevity of plastics for leaf springs under the loads a car would create simply to drop more useless weight from the cars (springs are a big weight in cars made mostly of kevlar.)

 

[OCR]

to make leaf spring we can use any plastic materials ?

You probably mean... fibre-reinforced plastics ?

If so, then yes...

We planned to use a massive front [roll] bar to achieve the roll stiffness we were after.

We found, however, that by spreading the body attachment of the front suspension fiberglass spring into two separate attachments 18 inches apart, we could achieve a major portion of the roll stiffness contribution of the front roll bar for free. We still used a massive front bar, but it would have been even bigger and heavier if it had not been supplemented by the leaf spring.

If I were involved in the design of a new passenger vehicle, however, I would give serious consideration to the use of a transverse composite single leaf spring of unidirectional glass or carbon filament in an epoxy matrix. This would be the lightest practical spring configuration and, although space constraints would seem to limit its use in racing, it should be perfectly feasible on road-going vehicles, from large trucks to small commuter cars. (Since I wrote this paragraph the new-generation Corvette has come out with just such a spring to control its independent suspension systems-at both end of the car.)

http://en.wikipedia.org/wiki/Corvette_leaf_spring

 

[dragoneyes001]

You probably mean... fibre-reinforced plastics ?

If so, then yes...http://en.wikipedia.org/wiki/Corvette_leaf_spring

figured someone had already been looking at this the shear weight savings of losing big steel springs would drop fuel consumption enough to be worth the effort.

 

[Dennis C]

Hey OCR, just want to state my admiration for Carroll Smith.
He took the fight for Ford to Ferrari and beat them at Lemans.
The man was a genius and an real Engineer "In Theory And Practice".
His books taught me so much when we started racing Formula Fords.
May He rest in Peace!

(sorry to go off subject here)

DC

 

[Baluncore]

Since the 1970s, airbag suspension systems have been gradually replacing leaf springs.

The leaf spring is simple and locates the axle relative to the vehicle body. Without a leaf spring there needs to be a swing arm with some additional sway control structure. The quality of the steel in a swing arm is lower than that needed for a spring because the continuous flexing does not lead to fatigue cracking as it does in springs. Unlike a leaf spring, the swing arm can benefit from the use of a hollow section.

The competition is not for a better material for leaf springs, but for a more durable and resilient rubber material.

 

[cjl]

Since the 1970s, airbag suspension systems have been gradually replacing leaf springs.

Not normally. Most cars use some kind of strut or double wishbone design with steel coil springs. Airbags are uncommon.

 

[Baluncore]

Not normally.

Coil springs are better behaved than leaf springs because they do not need to be tapered or laminated.

Leaf springs have been gradually disappearing. In light cars, leaf springs are usually replaced with coil springs. But in heavy vehicle suspension systems, leaf springs have been widely replaced by airbag suspension. Airbag suspension does less damage to the road than leaf spring suspension. Airbags permit higher tyre pressures which reduces sidewall flexing, they lower tyre temperature which extends tyre life. Airbag suspension is also easily adjustable.

 

[cjl]

Do trucks use air suspension typically then? That's fascinating - I didn't know that. I was purely referring to passenger cars, where coils are the most common spring type right now.

 

[Baluncore]

Airbag suspension is more expensive than coil springs.
Take a look at this; http://en.wikipedia.org/wiki/Air_suspension

Discussion re: the advantages to heavier vehicles; http://4wdaction.com.au/forum/viewtopic.php?f=10&t=97961&start=30

To see the availability of retro-fit bags for cars … google; airbag suspension kits