TABLE 5-1 Vehicle Mass Reduction Targets for PNGV Goal 3 Vehicle

System

Current Vehicle (lb)

PNGV Vehicle Target (lb)

% Mass Reduction

Body

1,134

566

50

Chassis

1,101

550

50

Powertrain

868

781

10

Fuel/Other

137

63

55

Curb Weight

3,240

1,960

40

SOURCE: PNGV, 1995.

materials for candidate powertrain components, such as fuel cells, flywheels, and ultracapacitors. However, no major studies in this area have yet been initiated by the PNGV Materials and Structures Team. Therefore, the present discussion is limited to materials for vehicle body structure.

Steel

Steel is the dominant material in use today for automotive body structures. Efforts sponsored by the American Iron and Steel Institute (AISI) are underway to reduce the weight of steel-intensive vehicles by 20 percent or more through improved design techniques, advances in manufacturing technology, and wider use of high-strength steels. An analytical study by the Ultralight Steel Auto Body international consortium forecasts a weight of 205 kg (450 lb) for a body-in-white 3, based on incorporation in the design of off-the-shelf, near-term approaches that relate primarily to Goals 1 and 2 (Martin, 1995). Although increased use of high-strength steel was included in the study, weight reductions were achieved primarily through design approaches rather than new materials. Such considerations are applicable to other metallic materials. Current activities form a basis for exploring and using more advanced technologies directed toward Goal 3 needs.

Ongoing studies are investigating steel-based materials with improved strength, ductility, and stiffness-to-weight ratio; methods for strengthening after forming are also being considered. Manufacturing studies are addressing increases in production rates for new processes for stamping and assembly, including challenges in joining dissimilar materials, such as the welding of steel to aluminum. A major focus is the development of a systems-based design approach that can be implemented on a desktop computer-aided design system rather than requiring a mainframe supercomputer, with associated accessibility problems. An important issue, yet to be addressed by the PNGV, relates to the

3  

Defined as the vehicle assembly, comprising the assembled but unpainted body, excluding glass, trim, and chassis items.



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