FEATURE

Motorcycle swingarm
redesigned in carbon
composite
Nigel O’Dea explains how the redesign of a motorbike swingarm
in carbon fibre epoxy prepreg was made possible by using the
Composites Modeler ply modelling and fibre simulation software
developed by Simulayt Ltd.

A
n engineering student at Swansea Ltd. The software provided a combination for this SMU project found little evidence of
Metropolitan University (SMU) in of design benefits and significant produc- the widespread use of structural composites
Wales has redesigned and manufac- tion cost savings by highlighting potential in racing motorbikes, with prior work
tured the swingarm (the main component of production problems during the design being confined to a couple of specialist
the rear suspension) from a Honda CRF450 phase and generating accurate flat patterns manufacturers. This has been attributed to
motor-cross bike and made it 31% lighter. for faster production, lower scrap and the complex shapes in a motorcycle chassis
The swingarm currently on the bike is made increased productivity. and the major design and production
from aluminium and weighs 3.9 kg including challenges faced as a consequence. By
bearings. The redesigned carbon fibre epoxy using a specialist composites software
Virtual product development
composite part with moulded-in metal package like Simulayt’s Composites Modeler,
inserts weighs just 2.7 kg, while retaining It is well established that composite which is fully integrated within established
the performance capabilities of the original materials offer significant weight reduction 3D Computer Aided Design (CAD) packages
Honda part. To minimise stress concentration opportunities. However, research carried out such as SolidWorks® or Computer Aided
areas and overcome various manufacturing
issues, the composite swingarm was vacuum
moulded in two separate sections. These
were then bonded together using the same
3M adhesive system that has been used
successfully in Formula 1 cars.

This swingarm composite redesign was

the final year dissertation project of B.Eng.
undergraduate Sven Lemmerling, supervised
by Dr Owen Williams, the SMU Motorcycle
Engineering Group course director. The
redesign of this complex shaped motorcycle
rolling chassis section in carbon fibre epoxy
prepreg was made possible by using the
Composites Modeler ply modelling and fibre
simulation software developed by Simulayt Dimensional copy of the original Honda swingarm design produced in aluminium.

38 REINFORCEDplastics NOVEMBER/DECEMBER 2011 0034-3617/11 ©2011 Elsevier Ltd. All rights reserved
 FEATURE

SMU used Simulayt’s Composites Modeler to simulate the draping of woven fabric
reinforcement over the mould surface. Blue or yellow indicates that the material
has to shear to an acceptable extent to conform to the curved surface. The flat
SMU used SolidWorks 3D CAD software to model the solid geometry accurately pattern is shown alongside the draped fibre orientations as a further check of the
and then build a virtual 3D model of the mould tool and the required metal inserts. manufacturability of a ply.

Engineering (CAE) tools like Abaqus/CAE, on the 3D solid model to be covered by the the best starting point of the draping process
it becomes viable for motorbike and other ply were selected. Next, a coordinate system is vitally important. Because of the speed of
engineers to consider advanced composite defining the basic orientation of the ply was Simulayt’s fibre simulation, Lemmerling was
materials for complex structural parts. identified, followed by specifying a nominal able to define the most suitable starting
rotation angle. Finally, a start point for the points rigorously at the design stage so these
Composites Modeler enables virtual product draping process (i.e. where the material is first could be used during manufacture so that the
development for composites by allowing applied to the mould) was defined. With these manufactured part reflected the design model.
the user to define the model in terms of key inputs set, fibre simulations could be run
plies in the same way that it is later manu- to identify the fibre orientations and highlight For the properties needed for this part,
factured. It then simulates the manufac- potential problems. The effects of changes MULTIPREG E722 epoxy resin with 2x2 twill
turing process to identify and correct design were immediately apparent, so the design 650 g/m2 carbon fibre prepreg from Amber
flaws and manufacturing problems. Doing could be improved within the CAD model. Composites Ltd was selected after extensive
this at the ‘virtual’ design stage allows the Finally, the stacking sequence of the individual lab tensile testing. Depending on the specific
design to be improved before money is plies was defined to complete the virtual area of the part, combinations of 0°/90° and
spent on tooling, and can avoid the need to model of the composite lay-up. -45°/+45° plies were specified to provide the
create costly prototypes or even throw away mechanical performance needed.
impractical designs. According to Lemmerling, a key advantage
of the Composites Modeler software for a Lemmerling explains how vital the
For the SMU project, SolidWorks was used to design engineer is that it can create accu- Composite Modeler software had been to
define the initial 3D CAD model of the mould, rate net shape flat patterns for ‘Gaussian’ the success of his project.
as well as the positioning of the various surfaces, which are ‘undevelopable’ surfaces
metal inserts. Having accurately modelled with double curvature and non-zero Gaus- “It would simply not have been possible for
the mould and part geometry in SolidWorks, sian curvature. For these types of surfaces, me to succeed with this project without this
Lemmerling then went on to use Simulayt’s the material has to shear to conform to Simulayt software, which was easy to use
Composites Modeler for SolidWorks software the surface, affecting the fibre orientations and is clearly specifically designed for fibre
to model the composites lay-up and generate and deformation of the material. Simulayt’s reinforced composite modelling. We did
manufacturing information. The functionality fibre simulation allows instant prediction of look at various other textile based software
in Composites Modeler allowed him to define these phenomena, allowing the designer to packages, but none of them were able to
feasible ply lay-ups rapidly while working in improve the design before it is too late. An calculate the optimised fibre orientation and
the familiar SolidWorks environment. important benefit of the fibre simulation at ply lay-up to obtain the required mechanical
this pre-production stage in a project is that performance in the final moulded carbon
it ensures ‘unmanufacturable’ plies cannot fibre epoxy component.”
Ply lay-up made easy
be specified.
Composites Modeler allowed Lemmerling to
Overcoming problems
define the composite lay-up in the same way A further complication of doubly-curved
as it would later be manufactured, on the surfaces is that there are infinite ways of The fibre simulations highlighted areas of
basis of individual plies. For each ply, faces covering the surface with fabric, so specifying excessive shear resulting from the draping

www.reinforcedplastics.com NOVEMBER/DECEMBER 2011 REINFORCEDplastics 39

 FEATURE

After completing fibre orientation and drape simulations using Composites Using the finalised composite design, a complete 3D model of the assembly
Modeler, the finalised composite part design with metal insets was created, with was created to validate the design and to make sure the swingarm would not
a mould design, a full description of the ply lay-up, and manufacturing interfere with the rear suspension, chain or wheel.
information including the net shape flat pattern ply data.

process, allowing the designer to optimise throughout the whole design tree. By accurate net shaped flat patterns for the
the ply shapes and fibre orientation. The identifying the problem at the design stage, plies can be cut manually, minimising trim
key benefits in being able to highlight considerable effort and cost were saved. wastage. Alternatively, for larger manufac-
problem areas at the ‘virtual’ CAD stage turers, production efficiencies can be fully
are firstly, a significant reduction in the “Using the Simulayt software, Sven was able exploited as the 2D flat pattern data can also
overall project design time, and secondly, to proceed to the manufacturing stage of be used to programme automated cutting
the avoidance of costly design errors. this swingarm project with a high degree machines to mass-produce kits of plies. These
Without Composites Modeler, these of confidence that the final moulded flat pattern shapes can be ‘nested’ manually
design errors would not have been composite part would have the mechanical or automatically before cutting to optimise
detected until after mould tooling and performance required for the application,” usage of expensive raw materials.
parts had been produced. notes Dr Williams, who approved the soft-
ware for this project.
Cost saving benefits
By identifying the While not so critical for a university research
Net shape flat patterns
problem at the design project with low production volumes, by
Traditionally, rough oversized flat patterns using the Composites Modeler software,
stage, considerable effort were created manually by a moulder using many OEMs and independent composite
paper. The paper patterns were then digitised convertors have seen significant overall cost
and cost were saved. and exported to a cutter. When the plies savings. A large number of design projects
were laid up in the mould, any excess mate- have become commercially viable due to the
For the SMU project, this proved invalu- rial was trimmed and usually scrapped. The faster flat pattern production, lower trim scrap
able in identifying very early on the need more complex the shape the greater the and overall increased productivity. Based on
to redesign a critical part of the initial inefficiencies and scrap wastage, which was comparisons between using the traditional
swingarm design around the suspension prohibitive for intricate parts. Now, a key manual flat pattern paper method versus
mounting lugs. In order to lay up suffi- benefit of the Composites Modeler software using the Composites Modeler software, ply
cient plies at the base of the lugs, the for manufacturers is that it now removes the production times can be reduced by over
entire design approach was modified to restrictions of traditional methods by taking 75% with 15% less trim scrap. This means that
reflect the opportunities and restrictions of 3D CAD data and immediately calculating a composite part fabrication which needed 50
advanced composites. This change resulted accurate two dimensional (2D) net shape flat hours labour time for flat pattern making and
in a different split line being incorporated patterns for dry reinforcing fabrics and resin- laying up and using £20 000 worth of prepreg
in the mould to enable a sufficient number impregnated prepregs. material, could be done using Composites
of plies to be laid down in this highly Modeler in under 12 man hours and save
stressed area. As Composites Modeler is This 2D data can be exported from Compos- around £3000 in ply trimming scrap.
fully integrated within the SolidWorks CAD ites Modeler in a standard DXF file format
programme, the late stage design modi- into a 2D drawing package to make very With such significant time and material cost
fications were automatically recalculated precise templates. Using the templates, savings, payback on the initial investment

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 FEATURE

The moulding process was faster overall, using the accurate net shape templates The composite structure was cured under vacuum in an autoclave to minimise
to cut out the flat ply sections. Composites Modeler produces a ply book of the voids. The bagging system needed considerable development to accommodate
composite lay-up to ensure that each ply is laid down correctly. the complex geometry of the component.

in the Simulayt software is easily achieved needed extensive development work, due to bike, which is currently undergoing on and
within a single production project. the complexity of the component geometry. off road trials to fully test the design.

Once the two sections were fully cured, they

Finished swingarm A complete chassis?
were demoulded, cleaned and then bonded
The final stage of the SMU project was to together using the 3M 9323 adhesive system. By proving the suitability of this composite
mould the two separate swingarm sections. The finished, fully assembled composite design approach in one of the most
The cut flat patterns for the plies were laid swingarm was given a show room finish by demanding areas of a motorcycle chassis,
up on the epoxy moulds in the sequence first using fine waterproof sandpaper, then further composite design projects are now
specified by a ply book generated by lacquering and polishing it to bring out the ongoing in the Motorcycle Engineering
Composites Modeler, after which the metal carbon fibre architecture. Group at SMU – the aim is to develop
inserts were positioned accurately in the a complete advanced composite racing
preform. The parts were vacuum bagged Engineering students in the SMU Motorcycle motorcycle chassis.
and cured under vacuum in an autoclave to Engineering Group have now fitted the rede-
minimise voids. The vacuum bagging system signed swingarm onto the Honda motocross “Sven’s work has provided us with the
knowledge and confidence to proceed
with similar projects,” Dr Williams states.
“We now have a number of different
studies underway at both undergraduate
and PhD level where we are developing
and characterising the modern competition
motorcycle. Our ultimate aim is to
produce a complete composite motorcycle
chassis, with the dynamics and handling
characteristics of current state of the art
machines.” Ŷ

Further information
SMU projects; www.motoeng.com
Simulayt Ltd; www.simulayt.com
Simulayt Ltd was recently acquired by Dassault
Systèmes, a specialist in product lifecycle
management (PLM) solutions.
Nigel O’Dea is an independent composites
PR specialist; e-mail: nigelodea@outsourcing
The complete carbon fibre swingarm. b2bmarketing.com

www.reinforcedplastics.com NOVEMBER/DECEMBER 2011 REINFORCEDplastics 41