Design a plastic fork that optimizes biodegradability – through factors such as surface-area-to-volume ratio (SA:V) – while maintaining a sufficient degree of structural integrity
Since the late 1990s, there has been an interest in creating biodegradable single-use plastic utensils. Many of the already existing biodegradable utensils are brittle and are unable to break down during the standard composting process. This inability to decompose contaminates other recyclable materials, which leads to them all getting discarded into landfills. In this study, the geometry of a fork is manipulated to determine if certain geometric features have a substantial effect on the degradation rate of a structure comprised of biodegradable materials. PLA is chosen as the material since it is made from renewable resources (typically fermented plant starches), has a lower carbon footprint, and requires less energy to create. PLA also degrades very well under commercial composting conditions and will break down within twelve weeks, making it a more environmentally friendly option when compared to traditional plastics.
Numerous designs of a fork using this material are explored, and the performance of each fork design is evaluated via multiple factors. First, to ensure that the fork has a comparable structural integrity to that of non-biodegradable forks, performance metrics are quantified for two load cases representing typical utensil usage. The designs are evaluated using factors such as maximum von Mises stress, maximum strain, and displacement, which are found using Finite Element Analysis (FEA) in Abaqus. We also strived to maximize the surface-area-to-volume ratio of the fork, which has been shown to significantly improve the rate of degradation. A full factorial Design of Experiments (DOE) was performed to explore the design space and determine which geometric parameters contributed most significantly to the desired performance metrics. An optimization study is then proposed to determine the best fork design based on these performance criteria. Using this process, we produce a singular fork design that not only functions as well as other forks, but also has a faster rate of degradation.