FOR AUTO RTM

FOCUS ON DESIGN
Automotive front axle: A glass act
The development of this glass fiber-reinforced car axle is a sign of the new,
expanded role composites will play in the design of future automobiles.
By Michael LeGault /Contributing Writer
» In what could prove to be a first in the commercial automotive
market, industrial transportation supplier Hutchinson (Paris,
France) has developed front and rear axles made from glass-reinforced
composites for the new Peugeot 208 FE, a hybrid electric
concept car that reportedly consumes just 1.9L of gasoline per 100
km. The switch from a traditional metal axle/suspension system
to one based on composites resulted in a weight savings of 20.4
kg, or roughly 40%. Peugeot, in collaboration with Hutchinson
parent company Total (Paris), designed the car to explore potential
ways to meet the stringent European regulations that stipulate
that automobiles emit less than 90g of CO 2
/km by 2020. The 208
FE easily meets this target, emitting a reported 49g of CO 2
/km, an
apparent world record for a pure (non-plug-in) hybrid.
Blade cuts weight
The Peugeot 208 FE, a hybrid
concept vehicle, is equipped
with front and rear axles (left)
made from approximately 50%
unidirectional glass/epoxy,
resulting in a weight savings of
20.4 kg (~40%), in comparison
to a metal suspension. In the
process, design engineers were
able to integrate or eliminate 12
distinct parts. Source | Peugeot
Hutchinson designed the axles, drawing on its experience as
a materials formulator and manufacturer of vibration control
technology for the automotive, rail and aerospace industries.
Hutchinson terms the structural composite heart of the axles
a “multi-functional suspension blade,” because it is designed
to incorporate in one part, four critical functions: suspension,
steering, anti-vibration/noise and anti-roll. During the development
process, design engineers were able to integrate/eliminate 12
distinct parts, including springs, spring holders, anti-roll bar, antiroll
bar fittings, the connecting rods of the anti-roll bar and the
wishbone (part of the steering) elements.
The radically new suspension actually has its origins in a unit
Hutchinson built for another European car manufacturer 20 years
earlier. Bertrand Florentz, technical director at Hutchinson’s
Composites Technical Centre (CTeC), recalls that part was production-ready
but cancelled at the last minute in favor of a traditional
steel suspension. Faced with the coming 2020 emission standard
and the penalties for failing to meet it, market conditions have
changed considerably for today’s automaker, and Hutchinson’s
experience with the earlier suspension
enabled it to quickly get up to
speed with a new, unique design for
Peugeot’s 208 FE.
Loads determine design
The first consideration when
designing an automotive suspension
is that the part assembly is subject
to both static loads (applied by the
car’s stationary weight) and dynamic
loads (those created while driving)
corresponding to tension, compression
and shear forces distributed
in all three spatial axes: longitudinal, vertical and lateral. The
dynamic forces imposed while driving can be up to five times
greater than the car’s static load; thus dynamic loads are the
determining factors in the part’s critical structural dimensions and
overall design, Florentz says.
Hutchinson’s preliminary “macro” design solution to the
problem of these multiaxial loads was to simulate the primary
suspension structure with a beam-homogenized orthotropic
model. The beam orthotropic model served as a “baseline” that
78 SEPTEMBER 2015
CompositesWorld