Primary Skills Developed:
Design Team Leadership
3D Modeling
Static Structural Analysis (FEA)
Design for Human Comfort
My contribution to this project consisted of leading and organizing design team meetings, designing a parcel basket, optimizing the chassis' dimensions and material, conducting finite element analysis (FEA), and editing the team technical report. Each point mentioned previously is explained further below and the full report for this project can be found in the last module of this page.
This year presented a novel challenge in leadership. Due to COVID-19, my fellow club officers and I were tasked with leading a group of individuals through a project in an entirely new virtual environment. During this semester (Spring 2020), our club was competing in two competitions under The Regional Human Powered Vehicle Challenge (HPVC): the Critical Design Review (CDR) competition and the Innovation competition. Accordingly, our club (seen below) split more-or-less in two with one half working on CDR and the other half working on Innovation. On top of our regularly scheduled club meetings, we would hold additional meetings for CDR and Innovation separately. Because of my interest in 3-D modeling and mechanical design, I chose to work in the CDR competition. With everyone settled into our separate team sections, we were ready to actualize our ideas. It's at this point where I began to exercise my leadership potential by taking the lead in the CDR meetings themselves. First, I created a shared "Who/What/When" document to precisely point out who needs to do what and when for our report. While this may seem rudimentary, a solid foundation is absolutely necessary for directed work to be accomplished in a timely manner. Furthermore, this "Who/What/When" document served as the hub for our CDR meetings from start to finish. During these weekly meetings, I would compile our tasks into categories and go through them one by one, assessing if the task had been completed and if not, assessing why it hasn't been completed and collaborating together as a team to get those individual team members the resources they need to accomplish their tasks for the following week. This structure, along with some friendly banter, helped our team finish our report well before the due date to a standard I can be proud of. To sum up, the enthusiasm, organizational skills, and environment of open dialogue that I developed here has made me a more adaptable and effective leader for my future projects to come.
When in comes to 3-D modeling, I started this semester with exactly zero experience; yet, through my club's extracurricular learning program, I had learned how use a computer aided design (CAD) program, SolidWorks, to design and assemble a 3-D model of our parcel basket (seen left). The goal of my design was to create a basket that was light weight, easily manufacturable, and small enough to fit onto the bottom of our chassis without interfering with the bike's chain link. To achieve these goals, I chose to use a lightweight material, 6061aluminum, and shaped it into overlapping circular tubes that would be easy to weld together and simply to bolt on to the chassis. The choice to go with overlapping circular tubing instead of a rectangular cross-section was influenced by the specific use and environment of our carrying device. Because this is a bike, I wanted to design this basket to hold water bottles and groceries while minimizing the amount of motion caused by the movements of the bike on the road. Due to the small grooves from the overlapping pipes, small bags of groceries and water bottles will fit nicely into those grooves for a snug fit. This design contribution taught me not only how to design parts in CAD software and mate them to an existing assembly, but also how to solve specific problems using engineering principles and techniques, an intrinsically valuable and rewarding skill to have.
Because our chassis could not be tested in person for stress and deformation, I relied heavily on finite element analysis to test whether our chassis was capable of withstanding forces both from the rider and from the road in the case of a roll over. The goal of my tests were to assess whether elastic deformation was within acceptable parameters and plastic deformation was nonexistent for two instances of vehicle roll-over: vehicle on its side and vehicle upside down. After our first iteration of finite element analysis, I found high stress areas at the junctions in our design that were outside our range of acceptable values. To mitigate these stress areas, I added supports to those specific areas. While these supports certainly helped, it did not change the amount of stress to a magnitude I was hoping for. At this point, I decided we needed to change something more fundamental about our design to account for these critical stress points. I considered two options: I could either redesign the entire frame with circular tubing and curved junctions or I could change the material. Due to a concern for our time constraints, I chose to change our material to something with a greater capacity to withstand stress. Originally we chose 6061 Aluminum for our chassis frame for its lightweight capabilities, but in the end I made the decision to switch to Alloy Steel for its exceptional strength. After switching materials and rerunning finite element analysis software, our design fell within our safety parameters and I compiled my findings in our written report. To conclude, this experience taught me how to navigate and interpret FEA in SolidWorks, the importance of having smooth curvature in a load bearing design, and the drastic differences various materials can have in their mechanical properties.
Because our recumbent bike is designed to be used in the real world environment, our bike necessitates a roll over protection system (RPS) in the event of an accidental roll over. With rider safety in mind, I needed to design our RPS to account for the size and proportions of the average human body. Because the RPS needs to extend beyond the body of the rider, I needed to define the average shoulder width and torso/head length. After finding data on average U.S. male proportions through the U.S. Census Bureau, I added a few more inches to account for the movements of the rider in the harness and came up with the approximate dimensions of 21in x 20in (seen left). To verify that this virtual design would work for a real person, we placed a virtual model in our design assembly and checked whether this exceptionally large model would fit comfortably while seated in our recumbent bike.
The document below contains the report my club submitted to the Regional HPVC Competition. After my teammates and I finished our designated sections, Antonio Cervantes (our club president) and I reviewed each section personally to ensure our ideas were clear, our delivery was organized, and our syntax was acceptable. Once Antonio and I had made some adjustments, we submitted our report to ASME Professional for grading. This experience taught me the importance of writing skills in the tech industry. Although much of our work is accomplished through programming, math, and software skills, the results of this work needs to be translated through written and verbal communication in order to maximize its efficacy.