JEC COMPOSITES MAGAZINE - Issue #82 - July 2013 - 38

suspension

Isogrid-stiffened automotive
suspension control arm

Gaius Automotive has created a compression-moulded composite
suspension control arm to demonstrate its design and manufacturing capabilities. A 40% weight saving was made possible by the
effective placement of unidirectional fibres between SMC charges
and the use of an isogrid-stiffened geometry.
Christian Jansen
CTO
Gaius Automotive Inc.

he automotive industry is
aggressively pursuing weight
saving programmes to meet CO2
emission and electrified vehicle range
targets. Significant to these programmes is the weight reduction of
suspension control arms. Not only do
lighter control arms reduce the weight
of the vehicle, but they also reduce
unsprung mass which results in better
ride quality, safety and handling.
These highly loaded, safety-critical
and fatigue-sensitive components
have been evolving from cast iron,
through stamped and welded steel
assemblies, to aluminium castings and
forgings (Figure 1).
While advanced manufacturing

techniques such as hollow casting
and thixo-casting have optimized
weight savings from aluminum [1],
the industry is looking to composites
for further improvements. The cost
of composite control arms currently
makes them suitable mostly for premium-class vehicles, however their
usage will spread to lower classes
within the next five years as processes
mature, raw material costs decrease
and lightweighting budgets continue
to increase.

An alternative to aluminium
Compression moulding of shortfibre composites has already been
established as a viable alternative to
aluminium, with substantial weight
saving potential [2]. To demonstrate
its proficiency in advanced composite
design, development and manufac-

Fig. 1: Evolution of the suspension arm. Delta values indicate typical mass savings between the alternatives

38 jec composites magazine / No82 July 2013

turing, Gaius chose to develop and
validate a compression-moulded composite control arm (Figure 2).
The control arm’s material system is
composed of two distinct phases: a
carbon fibre sheet moulding compound (SMC) and a unidirectional
prepreg. Custom-formulated materials
were co-developed with the PPG
Division of Advanced International
Multitech Co., Ltd. (Kaohsiung,
Taiwan). The SMC material consists
of 25mm-long 12K carbon fibre tows
at 53%w/w in a vinyl ester matrix.
Material properties were established
through coupon testing, and used
to populate property tables for FEA

About Gaius
Gaius is a design house capable of
product, material and process development from concept through production to disposal/recycling (cradle
to grave). Gaius is experienced with
composite structural laminate design
and analysis, process development
and verification, and has a processing
portfolio that includes hand lay-up,
prepreg compression moulding, RTM,
resin infusion, bladder moulding,
braiding, joining, machining and
assembly technologies.

JEC COMPOSITES MAGAZINE - Issue #82 - July 2013

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