UWE Bristol Engineering showcase 2015

Step 1
Yousaf Raza Bokhari
Aerospace Design BEng
The Design and Manufacture of a composite BMX Frame
Design 1: Monocoque Frame
Design 2: Lug and Tube design
Step 2 Step 3 Step 4
The major test results needed to show key performance areas in both frames were unable to be obtain because of many problems occurring during the FEA
and the testing of the constructed pieces. The results obtained from those two calculations showed the stiffness of the frame is able to compare and compete
with some current and past frames. The biggest aim of this investigation, to manufacture a complete carbon fibre BMX frame was achieved even without the
optimum tooling for manufacture. The mould from the previous year can be immensely improved. A better alternative would be to have a similar mould made
of aluminium. The benefit of this is it allows decreases the time needed to do a layup and to cure since the use of prepreg material becomes as option. Also,
although an aluminium mould is much more expensive than the current fibre glass mould, it has a much longer life before defects start to show in the mould
like the fibre glass mould already has. The longevity of the aluminium mould is worth the cost as it would definitely be better for value than the fibre glass.
This investigation showed it was able to determine the optimum technique for manufacture. The wet layup technique excelled in many qualities a modern
BMX frame should have. The finished frame was light and can be made even lighter if the correct amount of resin is applied with better tooling. The frame was
very strong and stiff with only 2 layers, where as if it was 4 layers, it would compete with modern frames in terms of stiffness while still kept relatively light.
The surface finish was one of the best outcomes of this investigation.
Project Supervisor
Dr. David Richardson
Project summary
An analytical approach was taken to
investigate the design and manufacture of
two composite BMX frames. Solidworks was
used to model the monocoque frame and lug
and tube frame and attempted to analyse the
model using finite-element. The monocoque
frame was manufactured using the wet layup
internal bladder method and the lug and tube
frame was manufactured using prepreg rollwrapping
method. A use of testing techniques
help determine the stiffness. Theoretical and
actual results are compared to and a good
understand benefits and problems of
different manufacturing method were
achieved.
Project Objectives
• To design a composite BMX frame.
• To analyse loads and stresses within the
BMX frames.
• To analyse and compare the composite
monocoque frame and the lug and tube
frame.
• To determine the optimum tooling for
manufacture.
• To determine the optimum technique for
manufacture.
• To manufacture a composite BMX frame.
Project Conclusion
Overall, the most appropriate method of
manufacture was the wet layup internal
bagging and from the results show a
monocoque frame seems to be superior than
the lug and tube but a fair analysis was not
made in this investigation so the question of
whether monocoque frames are superior
than lug and tube frame is still open to
investigation.