Dynamic Constitutive Behavior of Reinforced Hydrogels inside Liquid Environment

Abstract

Dynamic compressive behavior of three different types of hydrogels used for soft tissue applications are tested using a modified split Hopkinson pressure bar. Three kinds of hydrogels: (a) plain epoxy hydrogels, (b) epoxy hydrogels reinforced with three-dimensional polyurethane fibers and (c) fumed silica nano particles reinforced hydrogels with different cross linking densities are considered in this study. The three dimensional pattern of the fibers are generated by a rapid robo-casting technique. A pulse shaping technique is used to increase the rising time of the incident pulse to obtain dynamic stress equilibrium. A novel liquid environment technique was implemented to observe the dynamic behavior of hydrogels when immersed in water. Experiments are carried out for different strain rates with and without water environment. Preliminary results show that the yield strength of these hydrogels decreases when they are immersed in water.