UltraLight Steel Auto Body - Final Report - American Iron & Steel ...

1.2 Design philosophy and architecture
1.3 Packaging
PES determined to employ an holistic philosophy toward design
early in the design process. This holistic approach treats the
body structure as an integrated system rather than an assembly
of individual components, emphasizing total body analysis.
Through each iterative step, sophisticated computer re-analysis
confirms the effectiveness of the latest optimizations. The holistic
approach also allows evaluation of how other areas are affected
by these changes and where future optimization opportunities
exist. This approach promotes weight savings and improved
structural integrity by enabling engineers to reduce weight in
certain areas while strengthening strategic locations. The net
effect is the creation of a more efficient structure.
PES investigated various concepts to develop the optimum
ULSAB body structure. Some of these included full frame, space
frame, unibody and hybrid solutions. Criteria for the structures
under consideration were significant weight savings potential,
opportunity to achieve performance targets and assembly
possibilities in future full volume production body shops.
Early in the project PES engineers eliminated the full frame
concept because it offered no significant mass saving
opportunities. They also doubted that the full frame would meet
ULSAB’s structural performance criteria and were concerned
about high investment costs for assembly. Although a
spaceframe was considered, it was ultimately eliminated
because it was not considered as mass efficient as other
approaches. The PES team ultimately narrowed its investigation
to two structures—a unibody and a hydroform-intensive body
structure—finally settling on creating a unibody or monocoque
vehicle with key hydroformed parts.
The first step in packaging was to define the vehicle concept
type, exterior and interior dimensions and main components.
With these package definitions, package drawings were created
and structural hard points defined. ULSAB did not save mass
through downsizing: its wheelbase is 2700 mm; vehicle width is
1819 mm; and vehicle length is 4714 mm.
ULSAB Final Report 3