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Finite element and computational fluid dynamics evaluation of a clipless road pedal
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School of Engineering |
Master's thesis
Electronic archive copy is available via Aalto Thesis Database.
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en
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128
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Abstract
This thesis investigates the structural and aerodynamic performance of a commercial road clipless pedal and proposes an enhanced design utilising numerical methods. A baseline pedal (P1V1), which has been manufactured but not tested in extreme or long-term conditions, is used as the starting point. The work analyses how the pedal’s while simultaneously minimizing geometry and material of the pedal affect stress, fatigue life, and aerodynamics. The goal is to ensure compliance with ISO 4210-8 while minimising unnecessary weight without a major redesign of the current concept.
A complete simulation workflow was developed in ‘ANSYS’. The original pedal design was iterated several times to make different geometries (V0-V4). These designs were then tested under vertical loads that were similar to cycling and ISO proof tests (350 N, 850 N, 1150 N, and 1500 N). A mesh convergence and static structural analysis was used to identify the most effective geometry. After that, material charts and datasheets were used to narrow down the list of candidate materials. Then, detailed structural and stress-life fatigue analyses were performed on 17-4 PH Stainless Steel and Ti-6Al-4V used on the optimised pedal. Lastly, steady-state CFD simulations of a pedal-shoe assembly at three velocities (3, 5, and 8 m.s⁻¹) and three pedal angles (0°, 5°, and −5°) were used to calculate drag and lift.
The results show that optimising the geometry of the pedal body lowers the peak von mises stress by more than half when the proof load is 1500 N and keeps the deflections small. Both Stainless Steel and Titanium meet static and fatigue requirements. Stainless Steel has a higher safety margin, whilst Titanium has a lower mass. CFD predicts very small aerodynamic forces for all cases. This means that changing the design of the object just to reduce drag would not improve performance to remarkable extent. The study shows that the current pedal design can be improved through simulation to make it stronger and better at choosing materials. Aerodynamic effects are still considered as of secondary importance.