Thursday 10th July 2014

Audi to use GRP springs

UPDATE: They could be quite similar to the Renault items after all

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UPDATE: So it turns out the 'unnamed Italian supplier' for Audi's GFRP springs will be... the Sogefi Group, the parent company of Allevard Rejna who build Renault's composite springs. Oh. Will there be some slightly more advanced tech used as the parent company? Anyway, Sogefi's latest press release adds further benefits from the reduced mass, including a slight drop in CO2 (0.5g/km) on the road. Given the springs will first be used in an Audi 'upper mid-sized model' (so we'll assume A4/A6), the promise of 'more precise driving' is welcome. They're aren't known for dynamic prowess so it will be interesting to test those when they arrive later this year.

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Original story, has reported 30/06/2014:
Is Renaultsport out on a bit of a personal quest to wind up Dr Hackenberg and the other engineering titans at the VW group? Nicking the FWD 'ring record and moral high ground from SEAT probably rankled, the Megane 275 Trophy-R's use of composite springs among the much publicised technology that enabled it to do so. Slightly taking the gloss off Audi's announcement today it'll be using similar components on an as-yet unnamed 'mid-size model' later this year.

The Megane's composite springs from French firm Allevard Rejna are among the features setting the limited-run special apart from the regular 275 Trophy. Renault claims corrosion resistance and a subsequent longer lifespan alongside a 2kg weight saving as key advantages, saying it is "once more demonstrating its avant-garde approach with this solution, which is new on this type of vehicle." On Allevard's Sogefi Group parent company website it claims additional advantages, including environmental benefits from less energy intensive production, reduced susceptibility to catastrophic failure and even improved NVH.

Damn those pesky French again

So it's avant-garde versus the old Vorsprung Durch Technik then, Audi's unnamed Italian supplier developing a comparable GFRP (glass fibre reinforced polymer) spring with exactly the same claimed benefits. A steel spring for the car on which they'll feature would weigh 2.7kg, against the 1.6kg of the new GFRP one. And these savings contribute to reduced unsprung weight too.

How are they constructed then? Over to Audi. "The core of the springs consists of long glass fibres twisted together and impregnated with epoxy resin. A machine wraps additional fibres around this core -- which is only a few millimetres in diameter -- at alternating angles of plus and minus 45 degrees to the longitudinal axis. These tension and compression plies mutually support one another to optimally absorb the stresses acting on the component. In the last production step, the blank is cured in an oven at temperatures of over 100 degrees Celsius."

The press release continues, "The GFRP springs can be precisely tuned to their respective task, and the material exhibits outstanding properties. It does not corrode, even after stone chipping, and is impervious to chemicals such as wheel cleaners. Last but not least, production requires far less energy than the production of steel springs."

So there you go. Faster, smoother, greener and safer it seems the cure to all our motoring ills wasn't electric motors after all - it was composite springs. Who knew?

[otolith]

New application for a very mature materials technology.

[JDMDrifter]

Seems clever this!

[LuS1fer]

Well they couldn't go copying the Corvette composite transverse spring, now could they....

[FWDRacer]

Will this change there 4 spring duck technique?

[paranoid airbag]

LuS1fer said:

Well they couldn't go copying the Corvette composite transverse spring, now could they....

My first thought too

I wonder why this hasn't been done before if it's also less energy intensive to make. Is their fatigue performance up to snuff?

[otolith]

Cost, and a new focus on weight?

[scherzkeks]

Interesting tech., childish write-up.

[Mermaid]

scherzkeks said:

Interesting tech., childish write-up.

Lighten up

[TNH]

Mermaid said:

scherzkeks said:

Interesting tech., childish write-up.

Lighten up

Clearly lacking a spring in his step today

[kambites]

One day they'll catch up with all the best manufacturers and start making their body panels out of GRP too.

[RenesisEvo]

Not sure I agree that it's greener. Lighter, yes, but you I doubt you can recycle the composite spring in the same way you can a steel spring. More short-sighted feature-itis?

[aka_kerrly]

scherzkeks said:

Interesting tech., childish write-up.

Agree.

It's not like Audi have never been innovators of new technology, they just seem to be the butt of a lot of PH jokes now.

For me the slightly ironic thing about the Corvette is yes it has composite materials - to make leaf springs, an unusual mix of high and low tech.

[SturdyHSV]

aka_kerrly said:

For me the slightly ironic thing about the Corvette is yes it has composite materials - to make leaf springs, an unusual mix of high and low tech.

It's not a leaf spring like you'd see on a horse drawn cart though. It's not a 'low-tech' solution, honestly, it is literally just that there's a stigma attached to the phrase 'leaf spring' because of Top Gear

[aka_kerrly]

SturdyHSV said:

aka_kerrly said:

For me the slightly ironic thing about the Corvette is yes it has composite materials - to make leaf springs, an unusual mix of high and low tech.

It's not a leaf spring like you'd see on a horse drawn cart though. It's not a 'low-tech' solution, honestly, it is literally just that there's a stigma attached to the phrase 'leaf spring' because of Top Gear

I should have put a little at the end of my post.

I didn't expect the very next reply to be explaining the truth behind the leaf springs!

[RedSwede]

SturdyHSV said:

It's not a leaf spring like you'd see on a horse drawn cart though. It's not a 'low-tech' solution, honestly, it is literally just that there's a stigma attached to the phrase 'leaf spring' because of Top Gear

I'm not knoking the Corvette - I think it's certainly a decent car - but didn't the Volvo 960 (and maybe 760/940??) also have a composite transverse leaf spring? So not a unique setup - but why is it so rare a setup?

[skwdenyer]

LuS1fer said:

Well they couldn't go copying the Corvette composite transverse spring, now could they....

So... composite leaf spring tech was developed in the UK by GKN Composites. It was also developed in the US by TRW. Depending upon who you believe, the UK got there first. However, Corvette sounds sexier than Sherpa

[Mercury00]

I think the headline 'Audi to use springs' would've been more appropriate...

[Rich1973]

Vorsprung durch Papa

[Gixer]

RedSwede said:

I'm not knoking the Corvette - I think it's certainly a decent car - but didn't the Volvo 960 (and maybe 760/940??) also have a composite transverse leaf spring? So not a unique setup - but why is it so rare a setup?

Cost. Steel springs are readily available in all shapes sizes and spring rates. Corvette uses the transverse spring for a reason - it suits its low profile front end and allows more luggage space in the back - great for the golf obsessed marketers. Contrary to popular Top Gear opinion, the corvette has never cut corners with suspension set up and handling. One of the first mass produced cars to get ABS, traction control and the first to get magnetic ride. Lets face it a bit of steel rod wound into a coil isn't exactly high tech is it? :-p

RenesisEvo said:

Not sure I agree that it's greener. Lighter, yes, but you I doubt you can recycle the composite spring in the same way you can a steel spring. More short-sighted feature-itis?

I would say it is. A composite spring is supposed to take significantly more compressions / decompressions than a steel spring before degrading and is of course much lighter.

[DrMekon]

Mercury00 said:

I think the headline 'Audi to use springs' would've been more appropriate...