UWE Bristol Engineering showcase 2015
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Kawayne Learmond<br />
MEng Mechanical engineering<br />
Project Supervisor<br />
Dr Rohitha Weerasinghe<br />
Chassis Design For Formula Student 2016 Electric Car<br />
Introduction<br />
The contents of the study consists of many topics combining to achieve the aims and objectives. The initial start of the study was initiated by implementing a<br />
literature survey of past studies done on chassis designing abiding to SAE rules. The literature survey served as a foundation of the study of which ways was<br />
discovered how to improve and produce a great performance chassis. From that it was decided a combination of two types of chassis would be used,<br />
Aluminum honeycomb sandwich panel as a monocoque shell and tubular spaceframe inside. Aluminium honeycomb provides high strength to weight ratios<br />
compare to convention tubular spaceframe tubes used in formula student racing competitions. The most important loading case on the chassis is the combine<br />
bending and torsion gathered from the research. Other contents of the project involve calculating forces on the chassis, designing the chassis is solidworks and<br />
finite element analysing to verify the performance and validity of the chassis design. This study also involved manufacturing and testing of an aluminium<br />
honeycomb sandwich panel in three point bending test.<br />
Solidworks CAD modelling of the tubular spaceframe<br />
In previous <strong>UWE</strong> formula student chassis they have<br />
only created a tubular spaceframe chassis, due to its<br />
simplicity to build. The tubular spaceframe structure as<br />
shown in picture to right was created around the 95 th<br />
percentile male, and triangulated to stiffen the<br />
structure. The tubes was created by creating wire<br />
sketches then use the structure member tool to turn<br />
them into tubes.<br />
Manufacturing aluminium honeycomb panel<br />
The manufacturing of the aluminium honeycomb<br />
sandwich panels was fairly simple and short in labour<br />
time, although it takes 24 to cure for the epoxy used to<br />
bond the aluminium honeycomb core to the aluminium<br />
sheet metal skins. This validate the choice of material<br />
to make the chassis with in the study.<br />
Abaqus FEA Von mises stress<br />
To simulate the chassis in different loading<br />
conditions, the forces that could affect the<br />
chassis performance was calculated. The<br />
combined bending and torsion loading<br />
reaction force on the rear axle was 1620N<br />
and the front axle was 1037N simulating<br />
these reaction forces on the chassis<br />
produced Von mises stress of 124MPa<br />
shown in figure 3 is which is below the<br />
material yield stress of 150MPa<br />
Solidworks CAD modelling of the final Chassis<br />
After the tubular spaceframe was created, 3D<br />
sketches was drawn around it has the shape of<br />
the final chassis. The surfacing tool was then<br />
used to create the initial surface of the<br />
honeycomb panels then afterwards was<br />
thickened to the thickness of the panel<br />
calculated, which is good enough for FEA<br />
simulation. The design was challenging and<br />
successful.<br />
3 point bending test<br />
Study of the honeycomb panel during<br />
testing as setup shown in picture to left ,<br />
there was skin delamination at 7.9kN as<br />
shown on the graph to the right at point<br />
B. the honeycomb panel starting yielding<br />
at 6.5kN and produced a yield stress of<br />
19.5MPa, greater than stress produced in<br />
Abaqus from SAE forces on front and side.<br />
Abaqus FEA displacement<br />
The Finite element analyse of the chassis<br />
under combine bending and torsion loading<br />
shown also the displacement and prove that<br />
the chassis is really rigid, with its low<br />
displacement at 6.64mm , lower than the<br />
required maximum displacement of 25mm.<br />
This investigation can show that the 3D<br />
model can actually be created following<br />
further improvements in the second year of<br />
the study, mostly weight reduction.<br />
Project summary<br />
This investigation involves the research, design and<br />
analysis of the 2016 <strong>UWE</strong> formula student electric racing<br />
car chassis. The <strong>UWE</strong> formula student team compete<br />
yearly in the formula SAE event and the team needs a<br />
great performing chassis Abiding to the SAE rules <strong>2015</strong>, so<br />
that is what is done in the study.<br />
Computer Aided design (CAD) and Finite Element Analysis<br />
(FEA) software was used to create, test and evaluate the<br />
chassis. This identified the characteristics to prevent<br />
failure that could occur while racing.<br />
Project Objectives<br />
• Detailed research into chassis designing and<br />
manufacturing<br />
• Research and calculate the forces that chassis will<br />
be under for simulate in Abaqus<br />
• Create realistic 3D CAD model in Solidworks<br />
• Finite Element Analyse the chassis model in<br />
Abaqus<br />
• Develop knowledge in Automotive structures<br />
• Create a foundation for the study to carry-on into<br />
the second year of it<br />
Project Conclusion<br />
After the creation and FEA of the chassis model, it<br />
was verified that combination of Aluminum<br />
honeycomb sandwich panels and tubular space frame<br />
can produce a great performing chassis.<br />
The results from the FEA simulations showed that the<br />
chassis as more torsional stiffness than <strong>UWE</strong> 2013<br />
chassis and slight increase in weight before<br />
optimization of the chassis.<br />
The greater torsional stiffness will contribute to the<br />
improved handling of the car and ability to with stand<br />
loading with small deflections.<br />
This year’s study was a success and can be developed<br />
and improve into the second year of the study.
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