The British Touring Car Championship (BTCC) has captured the imaginations of millions of race fans in the UK with the roar of finely tuned engines and thrilling checkered-flag finishes for almost 50 years. In the 2003 season, fans are sure to keep an eye on the team that swept the driver, team and manufacturer titles in 2001 and 2002 – Triple Eight Race Engineering of Banbury, United Kingdom.
To verify and optimise their race car designs, Triple Eight automotive engineers use linear static stress analysis software from ALGOR to study a variety of the load-bearing components on their Vauxhall Astra Coupe race cars.
Unlike their consumer counterparts, BTCC cars are highly tuned for top performance. The cars weigh between 1150 and 1216 kg and generate loads in excess of 2 g in deceleration and 1,5 g when cornering. As with any racing competition, design optimisation to reduce weight and increase strength is critical. The British circuits are notoriously harsh and there is often contact during the races.
"The regulations in the BTCC dictate that the eternal motorsport battle between weight and strength of components is more important than ever, so we are now using ALGOR on parts that we would never have analysed before," said John Morton, Triple Eight's chief designer. "In addition, our designs are driven by very challenging lead times. We can only achieve results because of the good CAD compatibility and quick, user-friendly methods that Algor provides."
Algor's InCAD technology provides direct CAD/CAE data exchange and full associativity with each design change for Autodesk Inventor, which Morton uses when modelling the load-bearing components. Some of the components Triple Eight has optimised include the front upright, damper top mount, upper and lower engine mounts and front anti-roll bar blade.
"In our stress analysis work, we often need to analyse many different iterations of the same part very rapidly," said Morton. "When working with tight deadlines, the more quickly these iterations can be performed, the more optimised the part will be."
The front upright is the part into which the front axle is fitted and onto which all of the front suspension linkages, dampers and brakes mount. Loads induced by lateral acceleration and in-line deceleration can be up to 2g for a vehicle weighing up to 1216 kg. The main criteria for analysis are strength and stiffness. "This is arguably the most important component of the car, as it defines the front suspension geometry and the dynamic behaviour of the wheel," said Morton.
"Obviously, no failure due to stress can be accepted. In addition, any deflection incurred in service is undamped and can reduce grip and controllability." FEA was used to increase the stiffness by 16% while adding only 4% more weight.
The damper top mount attaches the damper to the chassis and absorbs all of the vertical loads created by the front suspension. "It is imperative that this part be as stiff as possible as it is loaded directly by the damper and any undamped deflection will have an adverse effect on traction," said Morton. "It is also, of course, analysed for strength but with a higher factor of safety to counter the effects of the oscillating load." FEA was used to increase the stiffness by 3% while reducing the weight by 24%.
The upper engine mount supports the engine and gearbox assembly that weighs close to 200 kg and is subject to harsh conditions induced by acceleration because it is rigidly mounted. "This part is one of the first parts we analysed with ALGOR and we ended up designing it in a way that we had never thought would withstand the loads," said Morton. "As a result of design optimisation, the new upper engine mount design is significantly lighter. FEA was used to reduce the weight by 38% while decreasing the stiffness by only 4%."
The lower engine mount also supports the engine and gearbox assembly and has to withstand lateral suspension loads. "Both strength and stiffness are of utmost importance as the lateral loads from the tyre are reacted directly through this part," said Morton. "A well-designed lower engine mount enables the front of the car to absorb lateral loads with very little deflection." FEA was used to strengthen this component by 75% while adding only 21% more weight.
Unlike most other car parts, the front anti-roll bar blade is far stiffer in bending along one axis than the other, so the stiffness of the anti-roll bar assembly can be reduced with a very quick alteration. "This part is highly loaded as it transfers vertical input from the front suspension through curb-strikes across the car," explained Morton. FEA was used to increase the strength of this part by 12% while maintaining the same weight. And, as Morton continues to integrate different types of analysis into Triple Eight's design process, he is utilising Algor's service and support.