High-strength steels cut third off weight of car suspensions

The weight of car suspension systems could be reduced by a third, at no extra cost, according to a two-year study by Lotus Engineering.

Extensive use of high and ultra-high strength steel thin-wall sections coupled with hydroforming and laser welding can cut the weight of vehicle suspension systems by up to 34%, reduce costs and improve performance compared with current designs.

In one case, Lotus redesigned an aluminium suspension unit in steel, cutting its cost by 30% and even reducing its weight slightly.

The UltraLight Steel Auto Suspension (ULSAS) study was undertaken on behalf of a consortium of 35 of the world’s leading steel companies, including Corus in the UK. It follows the UltraLight Steel Auto Body (ULSAB) study, completed in 1998.

The consortium wants to boost the use of steel by car manufacturers in the face of the rapidly increasing use of lighter materials such as aluminium and plastics.

The consortium asked Lotus to design five different types of rear suspension, including a twistbeam, double wishbone and a strut and links system, and to benchmark them against current systems.

Lotus also designed a new type of system specifying the latest steels. It looked similar to a double …wishbone system and was 34% lighter and slightly cheaper than a conventional double wishbone system.

The initial aim of ULSAS was to cut the weight of new steel systems by 20% and match the weight of an aluminium system at a 20% lower cost. The result was weight savings of 17-34% and costs equivalent to, or less than, current designs.

`The ULSAS study established that by applying the latest steel technology, car makers can match the weight savings made by using more `exotic’ materials while offering significant cost savings,’ said Peter Rawlinson of Corus, the ULSAS programme director.

Roy Woodward, consultant to the Aluminium Federation, said the ULSAS project had been driven by the need to match an existing aluminium system. `I’m sorry to hear they’ve succeeded’, he added.

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