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Audi set to cut vehicle weight with introduction of fiberglass springs

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July 2, 2014

Audi's GFRP springs (left) are lighter than the steel units they replace

Audi's GFRP springs (left) are lighter than the steel units they replace

The quest for ever-greater fuel efficiency is driving auto manufacturers to extreme lengths to reduce the weight of their vehicles. Aluminum, carbon fiber and fiberglass are all being used to help meet stringent emissions standards. In its search for "enlightenment," Audi has announced it will introduce glass fiber-reinforced polymer (GFRP) springs in its vehicles before the end of the year.

The core of the spring is made up of fiberglass strands, impregnated with epoxy resin and twisted together. Audi then uses a machine to wrap additional strands of fiberglass around the core and cures the unit in an oven. The strands are wrapped across each other at a 45-degree angle, to allow the load to be equally distributed across the whole spring.

So what benefits do the GFRP springs hold over steel? To start with, they don't corrode, even after damage by stone chips, and they're not impacted by wheel washing chemicals. In areas with snowy, salted roads, there are huge potential benefits to ditching steel for fiberglass.

Another key advantage over traditional steel springs is weight. In an upper mid-size car, Audi claims each individual spring weighs almost 2.7 kg (6 lbs), whereas its GFRP units weigh just 1.6 kg (3.5 lb). This adds up to a saving of around 40 percent. While a saving of 4.4 kg (9.8 lb) may seem insignificant, every gram saved contributes to lower emissions and a better driving experience.

Speaking of driving experience, Audi also claims the GFRP springs can be "precisely tuned" for the task at hand, be that ride comfort or a sporty feel, which allows the benefits to be felt across its whole range of cars. To top the whole package off, and in keeping with the low-emissions benefit of weight saving, the GFRP springs take less energy to produce than traditional units.

Audi plans to debut the springs on an "upper mid-size car" (presumably its A6 or A7) by the end of 2014.

Source: Audi

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19 Comments

Quite impressive! Are there any known downsides to using these new fiberglass springs?

Onihikage
2nd July, 2014 @ 11:21 pm PDT

Downsides... How about recycling? Steel just gets put back in the furnace whereas fiberglass goes to the landfill.

Tim Read
3rd July, 2014 @ 12:15 am PDT

Do they burn? These springs will be in close proximity to red hot disc brakes. I've seen fibreglass cars seriously burnt out.

Alien
3rd July, 2014 @ 12:50 am PDT

Think so......it has problems when it gets wet fro prolonged period.

Sahamate
3rd July, 2014 @ 02:41 am PDT

There is LOT of problems with fiberglass - I know because I design it for heavy industry. I simply do not believe that at the end the customer will have any benefit from it... Manufacturers are only trying to rip out more and more money from us.

Dziks
3rd July, 2014 @ 03:20 am PDT

The surest way to save fuel is to go slower, accelerate less and to brake less.

When it comes to suspension and spring materials you need to minimise the energy lost in internal damping, so a less comfortable ride. So drive more slowly too?

amazed W1
3rd July, 2014 @ 03:53 am PDT

The debris that damages the paint on the steel springs, what does it do to the fiberglass?

I haven't heard of disproportionate problems with the fiberglass leaf springs.

Slowburn
3rd July, 2014 @ 04:11 am PDT

I doubt that a marque such as Audi is going to put into production a component that does not meet their performance standards, which considering Audi's status, will be quite high. They have a lot riding on ensuring that their models are both safe and reliable.

Whilst a road spring failure is not necessarily too dangerous because the car will be able to proceed by riding on the bump stops, a failure could cause an accident, which in turn could cause fatalities. As for reliability, it will be tested exhaustively, both on a rig and on a pavé circuit with a considerable number of kerb strikes thrown in for good measure. There will also be a lot of whole vehicle testing in all sorts of climates and road conditions.

Considering the reduction in unsprung weight and what that means for ride comfort, I imagine that this is only the first of a range of components to be manufactured using this material.

Mel Tisdale
3rd July, 2014 @ 06:30 am PDT

Nothing new about composite springs, they weigh about 1/3 of a steel spring, last longer and reduce unsprung weight.

Amongst other vehicles, Chevrolet Corvettes have had them for years and my wife's Nissan Serena has one.

However, all the examples I have seen have been leaf springs - a sadly underrated configuration that can save a huge amount of space and height.

Catweazle
3rd July, 2014 @ 08:12 am PDT

Since the Corvette has been using composite springs for 50+ yrs, it's about time, Audi, others catch up.

For springs Composite have a natural dampening and quite steel does at 30% of the weight.

And proves there is no reason not to build an all composite car chassis/body at 50% of the weight with 2x's the strength in cost effective medium tech composites, not CF which is mostly costly hype.

Dziks, I can't believe you are in the industry making statements like that as I've been doing these in high tech racing boats, etc for 45 yrs now, not new at all.

I also have a 2x's stronger than steel at 50% of the weight body/chassis that also proves you are not correct.

jerryd
3rd July, 2014 @ 08:35 am PDT

That 40% saving in weight may be good for a car but it would be more impressive for a robot wouldn't it? Mobile robots tend to be much lighter than vehicles but still have significant forces which need dampening.

Snake Oil Baron
3rd July, 2014 @ 10:26 am PDT

Does that 40% weight reduction really help on 12 lbs per car?????

Dave Ussery
3rd July, 2014 @ 04:21 pm PDT

How much energy do they really hope to save in the cars lifetime? The entire car might get about 0,3% lighter but the saved energy due to that is just a small fraction of that %. I'm afraid it wont compare to the presumably higher energy spent on manufacturing and eventually recycling (if that's even possible).

Narrower tyres probably would save more because of less rolling resistance and drag (and also some weight) but I suppose most of the Audi buyers aren't that keen on slim wheels on their 'fat' car. ☺

Conny Söre
3rd July, 2014 @ 04:57 pm PDT

introduction of fiberglass coil springs

Fixed that for you. Corvette has used fiberglass leaf springs since 1984, 30 years.

Galane
3rd July, 2014 @ 08:06 pm PDT

@ Dave Ussery - How many cars does Audi build every year?

Slowburn
3rd July, 2014 @ 10:14 pm PDT

Weight saving is minimal. You would have to make sure you never carried any extra weight in the trunk, and only half filled your gas tank. Also don't transport heavy passengers. Get the idea?

I imagine fiberglass leaf springs flex less than coil springs.

windykites1
5th July, 2014 @ 04:11 am PDT

Basalt fibers have an almost 18 percent better elastic modulus than fiberglass, take much higher heat and cold, and are easily recyclable.

ZekeG
7th July, 2014 @ 12:41 pm PDT

@ windykites1

Just because the car is loaded means that making the car weigh less is meaningless. That is ludicrous.

What makes you think that leaf spring suspension has less travel that coil spring suspension?

Slowburn
10th July, 2014 @ 12:13 pm PDT

Just had a conversation with an aerospace composites expert about FRP springs during a recent flight. I am surprised that the coil format was adopted over "wave" or stacked/opposed disc springs.

Paulinator
11th July, 2014 @ 02:47 pm PDT
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