Background
The client (Dick’s Sporting Goods) wanted a lightweight and portable camping chair that mimicked the suspension system of a hammock. While interning at Bally Design, I assisted in developing chair designs, creating functional prototypes, and performing design analyses.
Concept Generation
In the initial stages of the design process, I worked with a team of industrial designers to brainstorm different methods of creating a chair suspension system that would mimic the feel of a hammock. To achieve this feel, our team wanted to ensure that there were no pressure points when someone sat in the chair. We planned to design a chair that would support the user by only the fabric. Various concepts were developed and then created in SolidWorks. These concepts focused on using fabric to form a cocoon-like shape around the user. I assisted the industrial designers with evaluating and refining the design to ensure that the size was appropriate and could be easily manufactured at a mass scale to ensure a low production cost.
Analysis
Before the construction of a functional prototype, I derived equations from a free body diagram (FBD) to determine the loads on various parts of the frame in relation to an individual's body weight. A weight of 250 lbs was assumed for the analysis. Once the loads were determined, a fatigue analysis was conducted using a program I developed in Python. This program determined the size of the frame to ensure the product had an infinite life.
Construction
Once the size was determined, a functional prototype was constructed. During this process, I was responsible for building the frame pieces of the chair, which another mechanical engineer welded together. An industrial designer was responsible for constructing the suspension system. This functional prototype gave us valuable feedback, such as realizing the seat was too narrow and thus needed to be modified to ensure the user was suspended entirely by the fabric and not directly by the frame of the chair.
Outcomes
During my time on the project, I worked through the design process and learned the value of functional prototypes to further refine and enhance a design. The prototype was shown to the client and was later brought into production.
Reflection
Although we made improvements from testing, the body types used to test the chair were similar. After the product came to market, reviews showed that the frame created pressure points on users' legs. This feedback taught me the importance of using a diverse base of people to test products.