Steel Industry Shows off Designs for Lightweight Auto Doors, Hoods, Decklids, Hatches

Designs Meet Safety, Cost, Performance Targets

DETROIT, MI, September 29, 1998 - The world steel industry has developed a range of design concepts for automotive doors, hoods, decklids and hatchbacks that could save more than 50 pounds of weight in an automobile. The closure concepts meet stringent targets for safety and structural performance and could be produced using current materials and techniques at little or no cost increase compared to conventional closures and those made with other materials.

The concepts are the product of the UltraLight Steel Auto Closures (ULSAC) study, a forward-looking companion to the comprehensive study of auto bodies released in March called the UltraLight Steel Auto Body (ULSAB). The two studies are part of the steel industry’s aggressive strategy to contribute low-cost, high-performance solutions to automakers’ goal to develop and market environmentally benign vehicles in the next decade.

The success of ULSAC’s advances rely largely on design concepts featuring thin-gauge, high and ultra high-strength steels, steel sandwich panels and burgeoning technologies including tailored blanking and hydroforming. The designs emerged from a holistic, clean sheet approach that treats the structure as an integrated system rather than as an assembly of individual parts. Fundamental to the earlier ULSAB project, holistic design is a computer-intensive, iterative process that emphasizes total structural analysis.

The aim of holistic design strategies is to achieve highly efficient, optimized designs. Structurally efficient designs require less mass to do their work than less efficient structures, and as a result, contribute to greater fuel efficiency in a vehicle. Greater fuel efficiency, in turn, contributes to reductions in a vehicle’s tailpipe emissions.

Like ULSAB, the ULSAC study provides concepts and techniques that automakers could use immediately in their next generation vehicles and fabricate with current and affordable materials and manufacturing processes.

As it did with ULSAB, the steel industry intends to produce demonstration hardware to validate the study. The hardware could be ready in 2000.

An economic analysis included in the study shows that by using ULSAC design concepts, automakers could reap steel’s environmental and performance benefits at little or no increase in cost, compared with conventional closures and those made with other materials. A major benefit of using steel is its relatively low cost. The analysis estimated costs of the concepts and compared them with estimates of conventional designs. The estimates considered materials, size, geometry and manufacturing.

Porsche Engineering Services, Inc. (PES) of Troy, Mich., conducted the study with oversight by the steel industry’s ULSAC consortium. The project comprised benchmarking, target setting, conceptual design, finite element analysis and cost analysis.

The benchmarking phase began with defining state-of-the-art design concepts, based on analysis of eighteen 1997 model automobiles from around the world. From these definitions, PES established mass, dimensions and structural performance standards for doors, hoods, decklids and hatchbacks. Benchmarking also served as the basis for setting dimensional, mass and performance targets for the ULSAC designs.

Following the benchmarking phase, the consortium endorsed PES’ recommendation to pursue new approaches for three common door designs: roof-integrated, frame-integrated and frameless. The consortium also accepted the PES recommendations for two hood designs: conventional and grille-integrated; and single designs for the decklid (conventional with tail type) and the hatchback (lift-gate type).

Throughout the design process, PES conducted finite element analysis on each part to confirm that local closure vibration modes would not coincide with body structure modes

The Automotive Applications Committee (AAC) is a subcommittee of the Market Development Committee of AISI and focuses on advancing the use of steel in the highly competitive automotive market. With offices and staff located in Detroit, cooperation between the automobile and steel industries has been significant to its success. This industry cooperation resulted in the formation of the Auto/Steel Partnership, a consortium of DaimlerChrysler, Ford and General Motors and the member companies of the AAC.

This release and other steel-related information are available for viewing and downloading at American Iron and Steel Institute/Automotive Applications Committee’s website at http://www.autosteel.org.

American Iron and Steel Institute/
Automotive Applications Committee:
AK Steel Corporation
Acme Steel Company
Bethlehem Steel Corporation
Dofasco Inc.
Ispat Inland Inc.
National Steel Corporation
Rouge Steel Company
Stelco Inc.
United States Steel Corporation
WCI Steel, Inc.
Weirton Steel Corporation