Brake Pedal Tray

In the previous years, the tabs that held the master cylinder bolts in the rear of the pedal tray did not perform well under the bending moment caused by the master cylinder (MC) push rods and fluid pressure. As well, it was suggested that the tabs be welded on to ease manufacturing. This year I designed truss-like MC tabs to counteract the bending caused by MC force in the rear. As well, Al6061 is heat treated and its tensile strength drops by 54% if welded, which is not ideal since the pedal tray must support a 2000 N force. I decided against welding and I was lucky enough to find a CNC sponsor who could manufacture the part for the team as one integrated piece with the tabs and the pedal tray.

To validate the design, I did ANSYS Structural FEA to ensure that it met our minimum required safety factor of 2. The FEA results showed that the UT23 tray has a minimum safety factor of 2 near the edge of the tray and the tab. Whereas, the UT21 pedal tray (the old design) had a minimum safety factor of 1.35. So, the new tray is 48% safer and meets the minimum structural criterion.

370 MPa is the highest stress which occurs on the corner of the carriage not the pedal tray. There was a minimum safety factor of 0.74367 at max equivalent stress point on carriages that are bolted to the bottom of the pedal tray and is not being studied due to poor meshing on that part, so that was ignored.

For UT23 (new design), on the edge where the tabs end and the tray is also discontinued, the lowest safety factor occurs. But on UT21 (old design) since the radius on the transition of the width in the back is larger, the smallest safety factor belongs to the front bolt hole. Because a minimum safety factor of 2 on the pedal tray in the risky regions was acceptable, the front tabs were not changed to increase the safety factor higher as that would mean adding more mass to the part which was not aligned with the constraints. From the total deformation study it became evident that at the very back of the MC tabs, the max deformation happens which is 0.4mm for the old design and 0.2 mm for the new design.