Two-scale modeling of nano-clay-filled shape memory polymers

Abstract

Shape memory polymers (SMPs) are introduced as polymers that have the ability to return to their early programmed shape after exposure to an external stimulus. Enhancement of the material with nano-clay filler has improved its thermomechanical properties and increased the range of its applications in many fields of industry. Due to the tiny size of filler and the heterogeneous nature of the material structure at different scale levels, characterizing the material’s thermomechanical flow using conventional experimental equipment is a far-fetched task. Furthermore, providing one numerical model that is able to simulate the material thermomechanical behavior by including all the effects of the lower scale material structure is also very hard. In this study, a two-scale modeling approach is developed by a combination of the numerical homogenization scheme, 3D Representative Volume Element (RVE) concept, and finite element method. The effects of the filler weight fractions on the overall effective elastic constants as well as the material flow under a finite deformation are investigated. The resulting elastic constants and the stress–strain curves show a fairly good agreement with the analytical results. Furthermore, all the investigated results provide a deep understanding of the material behavior and a starting point for the next higher scale level modeling approaches.