JEC COMPOSITES MAGAZINE - Issue #81 - May/June 2013 - 35

Design

Carbon fiber isogrid-stiffened automotive suspension arm
In this work, an aluminum automotive
suspension control arm was re-designed
to use carbon fiber composite materials.
This material substitution required topology changes, material innovation and
process development, and the end result
shows an impressive 40% weight savings
compared to the aluminum part, with
only a slight increase in deflection. An
isogrid rib pattern was employed to increase part stiffness and stability, and the
composite system is comprised of vinyl
ester and chopped carbon fiber molding
compound, and unidirectional prepreg in
a toughened epoxy matrix.
A rubber isolator bushing is co-molded
with the arm, eliminating the need for
secondary operations. Cycle time is primarily driven by the cure time requirement of the epoxy resin system of the
prepreg phase, and is presently 11 minutes. Follow-up research is already under
way to evaluate the use of modified vinyl

ester and fast cure epoxy resins, which
will facilitate a cycle time reduction to
5-6 minutes. both the prepreg and the
SMC materials are supplied in a sheet,
and are cut on a CNC cutting machine to
minimize waste. The composite charge
consists of ten flat unidirectional prepreg
layers sandwiched between stacked and
shaped carbon fiber SMC meso-charges.
There are two ten-layer stacks of Ud
placed in the two outer flange areas.
These charges are inserted into both the
top and lower mold halves, achieving
80-90% mold coverage. Mold halves are
prepared off-line so charge placement
does not impact the overall cycle time.
The global market for advanced lightweight suspension arms is estimated at
over USd 300 million, and smaller, agile
companies are well positioned to spearhead this paradigm shift in technology.
This work is easily scalable and transfer-

Winner: gaius Automotive (Taiwan)
Partnership Network: Topkey Corporation (Taiwan), Advanced International
Multitech Co, Ltd (Taiwan)

rable to other suspension elements, and
other highly loaded structural parts of
the vehicle. Such parts include currently
cast aluminum door and window frames,
suspension and subframe mounts and
composite chassis inserts.
As always, substituting more expensive
materials have to be evaluated in terms
of overall vehicle cost, emissions and
performance benefits.

Process

Development of a woven and long glass fiber reinforced rear bumper
back beam, using press and injection molding process

Winner: Lotte Chemical Corp
(republic of Korea )

The goal of this innovation was to
improve the strength of glass fiber
reinforced PP composites from external
impact with relatively low glass fiber
content reinforced by weaved high
impregnation (>99%) of continuous
fiber and LFT pellet. The extrusion and
injection processes are combined to
increase structural strength as well as
the degree of design freedom so that it
is possible to design various products.
The value created by using composite
materials is the resistance of shear stress
using high impregnated reinforcement
and continuous glass fiber reinforcement using PP resulting in improved
strength. The main advantage of this
innovation is that it can replace steel,
aluminum, and gMT bumper beam
used to rear bumper beam. by exten-

sion, the front bumper beam could be
replaced.
The key benefits are weight reduction

by PP/gF composite and applying to
various products using combination of
extrusion and injection process.

No81 May - June 2013 /

jec composites magazine 35

JEC COMPOSITES MAGAZINE - Issue #81 - May/June 2013

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #81 - May/June 2013