Modeling the dynamic response of low-density, reticulated, elastomeric foam impregnated with Newtonian and non-Newtonian fluids

Abstract

Engineering cellular solids, such as honeycombs and foams, are widely used in applications ranging from thermal insulation to energy absorption. Natural cellular materials, such as wood, have been used in structures for millennia. However, despite their extensive use, a comprehensive understanding of the dynamic interaction between the interstitial fluid in the cells of the foam and the foam itself has yet to be developed. In this thesis, we explore the dynamic, compressive response of low-density, reticulated, elastomeric foam impregnated with Newtonian and non-Newtonian fluids. To develop tractable analytical models for this complex, non-linear phenomenon, a study is first undertaken on the permeability of foam under deformation. Using these results, a model is developed for the dynamic, uniaxial compressive response of low-density, reticulated, elastomeric foam filled with a viscous Newtonian fluid. This comprehensive model is found to be well approximated by a simpler model, based on the lubrication approximation. Furthermore, in the lubrication limit, a model for the dynamic, uniaxial compressive response of foam filled with a non-Newtonian fluid is also developed. All of the models presented in this thesis are supported by extensive experimental studies. The experiments also suggest that these models are applicable over a wide-range of parameters, such as strain, strain rate, and pore size. Finally, these models are used in two case studies to assess the feasibility of composite structures containing a layer of liquid-filled foam in dynamic loading applications. The first case study focuses on applications in energy absorption with the experimental design of a motorcycle helmet. The second case study focuses on applications in mitigating the effects of blast waves with a parametric study of the design of a blast wall.

(cont.) These studies provide insight into the usefulness of the models and demonstrate that composite structures with a layer of liquid-filled foam have enormous potential in a wide range of dynamic loading applications.