Background
For my senior capstone design project, I worked with four other students to design, build, and test a prototype Burning Man vehicle over eight months. Burning Man vehicles serve not only as a means of transportation but also as some of the main pieces of art at the festival. Our objective was to design a vehicle that met the rules of the festival, reflected Ohio State school spirit, and could be safely operated by a single user. As part of the project, a tricycle conversion kit was designed, manufactured, and tested by the team. My role on the team was performing analyses of the design, modifying the design using results from the analyses, and developing manufacturing plans.
Concept Generation
When developing concepts, we wanted to create a vehicle that could be operated in a variety of environments and be easily operated by a user despite the added weight of an art structure. We wanted to ensure the operator was enclosed in the vehicle to be protected from inclement weather and could operate the vehicle without much physical effort. In our initial brainstorming sessions, we investigated different means of achieving these goals and the functions associated with them. These ideas were documented and then assessed using feedback from early sizing and analysis. After determining which concepts were feasible, we developed complete concepts from individual components. These complete concepts were then evaluated and compared to determine a leading solution. We performed further analysis and testing to refine and enhance the design.
Initial Sizing & Analysis
In initial sizing and analysis, calculations were performed to determine whether concepts met requirements and establish the size of components. In this stage, I performed calculations to figure out how much torque was required to drive the vehicle. Using this information, I was able to ascertain what size of an electric motor would be necessary and the amount of power that would be required to operate the electric motor. This analysis demonstrated to the team that an electric motor would not work with the budget allotted, and thus different modes of propulsion needed to be considered. Calculations were performed to determine the feasibility of a human-powered vehicle. Based on research and analysis, it was determined that the vehicle could be operated on human power alone.
Design
After moving forward with a leading concept, I designed a bicycle-to-tricycle conversion kit in SolidWorks. The frame of the bicycle was reconstructed in CAD to ensure the conversion kit would seamlessly fit onto the bike frame. I modeled various renditions of the conversion kit in CAD so that they could be compared to each other. The team’s goal was to create a robust design that could be easily manufactured and installed on an existing bike frame without making any modifications. During the design process, I utilized results from FEA and feedback from manufacturing experts to create a conversion kit that could be easily manufactured and minimized stress and deflection on both the conversion kit and bicycle frame.
Additional Analysis
Further analysis was performed on the leading concepts determined in the concept generation phase of the project. This process involved determining the correct gearing and completing a stress analysis on the conversion kit. To ensure that the bicycle-to-tricycle conversion kit would be able to withstand the loads expected during use, I imported SolidWorks models into ANSYS for finite element analysis. By applying proper boundary conditions and verifying results with hand calculations, I was able to determine areas of high stress and deflection. Using these results, I made adjustments to the material and geometry of different components in the kit.
Manufacture
Once the bicycle-to-tricycle conversion kit design was finished, I created manufacturing plans. This process involved determining manufacturing methods and the tolerances of different components. Manufacturing experts were consulted during this process to ensure tolerances could be met with the manufacturing methods available to my team. After finalizing these plans, my team and I manufactured the components at the student machine shop at Ohio State. These machined components were then assembled and installed on the bicycle. The art body was fitted onto the frame of the bike after the bicycle-to-tricycle conversion kit was added.
Test
To ensure our design met the requirements we set out to achieve, we developed a set of tests to evaluate our design. Tests included verifying the bike's turning radius, stability, visibility, water resistance, strength, and stopping distance. These tests demonstrated that the bike functioned as intended and met all requirements.
Outcomes
Over the eight months of working with my peers, I learned how to work in a team environment and collaborate with fellow engineers. This process enabled me to become more comfortable with the engineering design process and the use of analysis to feed design. A final, functional prototype that met our objectives was delivered.