One of the core
reasons why we build our parts out of wood for testing is to be able to see
from an early point on the weaknesses and flaws in our designs. Instead of
complicated stress modeling with computers, we simply cut our designs in wood
and subject them to physical stresses.
In this case, the
precaution paid off, as the magic finger jointed footrests failed.
The Necessity of Prototyping
Although the final
construct would be made of 0.25” thick aluminum and not wood, it allowed us to
see the bending stresses in the structure and how it might lead to repeatedly
failure over time.
Thus, we decided to
take a different approach to the footrests.
Presenting the Mark II
– Now 9001%* less likely to fail!
*Not an actual calculation.
In the previous
footrests (which we shall posthumously dub the Mark I), we saw the issue of a
large bending moment arise. To solve this in the Mark II, we used a spare
section of the 80/20 we had lying around to form a single long footrest bar.
Then, we cut out another 2 sections of 80/20 to lower the footrest from the
frame.
Attached
to Celeris’ mainframe
After doing some preliminary fitting, we
cut off the excess length of 80/20 from the footrest bar, and secured it firmly
to the mainframe. It now feels significantly beefier – and certainly reassuring
for the driver.
More crucially, however, the front axle holder
was destroyed during testing. As the holes did not fit the bearing casings
perfectly, that little bit of wiggle room meant that the shaft would lean
backward, pressing upward on the lower plate, causing the rupture.
Rupture
View 1
Rupture
View 2
In
lieu of this, we decided to replace the standoffs in front with an 80/20 bar,
which should provide additional resistance against bending and hopefully
prevent another rupture.
