Authors: James Walker
Mentors: Pania Newell
Insitution: University of Utah
During the COVID-19 pandemic, the discussion of using fibrous porous materials in the context of face masks has gained significant relevance. These materials consist of networks of fibers that are intertwined through weaving, knitting, or bonding, creating a structure with interconnected pores that facilitate the transport of gasses and liquids. When a face mask is used, it is under tensile stresses that can greatly affect its longevity and behavior, and simulating the behavior of the fibers within the mask under this loading is essential in enhancing its robustness. Numerical analysis involving fibrous porous materials is challenging due to their inherent randomness and anisotropy, however. The models we use need to accurately represent the entire mask, which we achieve using a small cubic cell known as a representative volume element (RVE). In this study, we systematically investigate the role of fiber diameter, fiber cross sectional shape, and RVE size on the mechanical properties of various RVEs using a computational framework built on the finite element method. The RVEs themselves are idealistic, but useful networks of polypropylene fibers that are orthogonally intersected within cubic boundaries. Our results show that once an appropriate RVE size was determined with constant porosity between systems, the stiffness of the samples increases as the cross-sectional shape progresses from a triangle to a square, to a pentagon, etc., largely due to the increases in intersection volume between fibers. We also found that increasing the diameter serves to increase material stiffness. This project not only offers insights into designing more robust face masks but also provides novel tools that can be used for designing other fibrous porous materials.