RACE TYRE DEVELOPMENT 6 April 2016 premium tyre brands it’s easy to overlook the major contribution of Dunlop to motorsport. Dunlop is a major player, particularly as a technical partner to BMW in GT Racing, in the American Lemans Series (ALMS), Nurburgring 24 Hour and Intercontinental Lemans Cup (ILMC). Many of the club racing and endurance racing series in NZ also use Dunlop race tyres. It’s not until you look around a tyre plant do you realise how manually intense tyre production is. Most preconceptions of highly automated processes with tyres rolling off conveyor belts and being stacked to the roof in windowless warehouses are way off the mark. At Dunlop Motorsport each tyre is virtually hand made with the aid of huge machines and lots of sophisticated background compound chemistry processes. The factory in Birmingham resembles the Dark Satanic Mills of old, probably because of the carbon black in the air and that unmistakable ‘rubber’ smell that you’ve gotten used to, since you visited your first bicycle shop. Many other preconceptions are false too – very little natural rubber is used in tyres. “In my department we tend to concentrate on GT and Sportscars in GT2, GT3, LMP1, LMP2 – Dunlop Sportscar and GT product comes out of this office,” says David Meenan, a design engineer with Dunlop F E A T U R E – WHERE PHYSICS AND CHEMISTRY MEETS BLACK ART Most people tend to regard tyres as just black doughnuts that separate their car from the road and involve an irritating running cost to be minimised every couple of years. Racers on the other hand are very pickie about their rubber and are willing to go to extreme lengths to test and effectively calibrate their racecar to the rubber and the circuit, so that they can arrive at each new circuit with the optimum set-up for the first day’s practice. It’s not until you take a detailed look at tyre design and manufacturing processes that you begin to understand the complexity of this ‘Black Art’. There are lots of ‘normal’ design and manufacturing considerations in the tyre design process, but at the margins there is considerable informed guesswork and approximations that produce the goods that racers depend on. In many ways tyre design is similar to aero design – you check your basic scheme with CFD, you make a wind tunnel model, you test it and then you test the full size car on the track. With tyres you do the same basic geometric CAD things that you would do with any component. What’s different is the analysis. Rubber By Charles Clarke (it’s not actually rubber – almost all compounds are synthetic these days) is hideously non-linear (the stress is not directly proportional to strain) and each compound behaves differently. You have to use a specialist non-linear analysis code to stand any chance of simulating the behaviour of the tyre. Here’s where Abaqus and Simulia from Dassault Systèmes comes in. A lot of intellectual endeavour by hundreds of developers over several decades has made Abaqus probably the best non-linear analysis code available. As important as the developers are – the technical partnerships with tyre companies make the software what it is today. Companies like Dunlop Motorsport who are continually pushing the technology to its limits to provide the best service for their racing partners, are essential in the development of the simulation software. With the high profile of Bridgestone, Pirelli, Michelin and other
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