Copy of project Cruzee ProV wheel by @joshdeetz.
Although the idea of designing a bicycle may seem elementary, weighing in important factors may have a significant impact on the final outcome. Moreover, a simulation performed on a simple geometry helps give a better insight into the physics at the macroscopic as well as the microscopic level.
The choice of material plays a major role in the behaviour of a material under loading. The stress-strain curve describes this behaviour accurately. Simulation helps us study the non-linear plasticity effects on a wheel rim and determine the role played by the material type on the physical significance of the result.
Hence, the analysis is to be done post the yield strength point (non-linear region) of the wheel rim material, i.e., Polypropylene.
This project showcases the capability of the SimScale platform. The static stress analysis of two children’s cycle wheel models (a 5 spoke model and a 3 spoke model) are performed. The primary objective is to investigate how the 3 spokes wheel case performs compared to the 5 spoke wheel case.
3 spoke and 5 spoke wheel models
Polypropylene (PP) is considered as the material for both cases. For each of the wheel types, two main cases are considered, one with 35 kg radial load and the other with 7.5 kg lateral load.
A static simulation is performed for each of the cases and an inference is derived by comparing the results. A more elaborate description of the simulation set up and results may be obtained in the next section.
Results and Conclusions
Both cases are discussed below. In both cases, the deformation is scaled 1500 times in order to see the difference. This can be done by applying “WarpbyVector” filter with displacement scale factor of 1500.
Before proceeding with the final cases, a test analysis is performed using both models in order to estimate the required refinement of the mesh, especially in areas with high stresses. Based on this analysis, the meshes for the final cases are refined. Consequently, well refined second order meshes are made for the further analyses, which are discussed below.
Radial load case
This case involves a radial load of 35 kg that is applied to both wheels. Since this load is applied to the partitioned faces of the geometries, first geometries are modified and required surface partitions are introduced. The figures below show the vonMises stress contour plot for both cases i.e. 5 spokes case (right) and 3 spokes case (left). Clearly, the 3 spokes case doesn’t quite offer the required stiffness and gets deformed as compared to the 5 spokes case. Due to a large deformation, one can observe high stresses in the 3 spoke wheel case, especially on the curved regions.
Lateral load case
In this case, a lateral load of 7.5 kg is applied to both wheels. The figures below show the vonMises stress contour plot for both cases i.e. 5 spoke case (right) and 3 spoke case (left). Again the 3 spoke wheel deforms extensively, providing lesser stiffness than the 5 spoke model. As before, high stresses can be observed in the 3 spoke wheel case, especially in the curved regions.
Through this analysis it can be deduced that the 3 spoke wheel gives a poor resistance to a specified load, being easily deformable under given conditions. Whereas, the 5 spoke wheel is much heavier but provides a greater degree of stiffness and resistance to the applied load.