EXPLORATION ’94 — Lighter cars focus of research

The steel industry and automakers have begun work on new ways to design and engineer car bodies that could make them up to 20% lighter, trebling current potential for weight savings.

The results of this work will confirm energy-efficient steel as the preferred material for carmakers and will underline its structural and cost advantages over alternate materials.

The use of the latest steel materials and manufacturing technologies coupled with optimized computer-assisted lightweight design can also substantially improve safety, noise vibration and handling. It can significantly cut automakers costs and at the same time save energy by providing better fuel economy in the automobile and cutting the amount of energy needed to produce the car in the first place.

A panelist at last year’s 27th conference in Paris of the International Iron and Steel Institute, Ludwig Hamm, in charge of body engineering at Porsche AG, said that assuming weight reductions of only 15% in the car body, fuel savings on new cars produced in North America and Europe would reach 800 million litres annually.

Because steel car-making technologies are applied universally, this lightweight potential can be rapidly transferred to the entire new car fleet, Hamm stated. By contrast, plastics and aluminum, which must still develop large scale automotive manufacturing technologies, are only entering small series production.

World carmakers use about 45 million tons of steel to produce some 35 million passenger cars annually. In recent years, steelmakers have aggressively partnered the auto industry in developing high performance steels and improving steel properties, so as to create leading-edge production systems that will be hard for alternative materials to replace.

In his presentation, Hamm listed seven ways in which computer design technology — which has rapidly advanced in recent years — is helping the industry consolidate these benefits even further. “By optimizing solutions at an early stage with dramatically reduced risks and less costly tests, today’s computer techniques create the conditions for lightweight design of future steel bodies,” Hamm stated.

Porsche’s U.S. engineering affiliate, Porsche Engineering Services, is a partner with the American Iron and Steel Institute (AISI) and the Ford Motor Company, in a project to investigate use of advanced systems engineering approaches in steel-bodied vehicles using an existing Ford Taurus as basis for comparison.

In Europe, German carmakers Audi, BMW, Mercedes-Benz, Porsche and Volkswagen, in co-operation with German and French steelmakers, are launching a parallel project to develop advanced ways of designing and producing lighter, stronger body components and sub-assemblies out of high strength steels. Co-funded by the European Community, the program, which includes development of new car plant technologies, expands the scope for integrated design still further. A major goal of the project is to lighten cars and improve their performance by optimizing the rigidity-to-weight ratio of the body structure. To do this, the entire body is analyzed as an integrated system. This “holistic” approach identifies the structural parts which can be strengthened, allowing other body sections to be considerably lightened.

“It can eliminate as many as 50 parts from the car body, yet maintain optimum results for rigidity, crash energy management, manufacturing and assembly,” says Peter Peterson, a member of the AISI automotive applications committee and director, marketing automotive, U.S. Steel.

Together with new technologies such as continuous laser welding, parts integration and optimal use of high-strength steels, integrated design can bring theoretical weight savings of nearly 30%, “although in practical applications, savings of 15% to 20% will be achievable,” Hamm said. Without integrated design, weight savings of more than 5% would be difficult. Because the approach uses steel more efficiently and results in fewer parts in a body-in-white (the monocoque car shell), it translates into less weight and less cost, Hamm noted. “Fewer parts require fewer dyes and fewer sub-assemblies, which means less manufacturing complexity and potential lower capital cost for manufacturing equipment,” he said.