Finite Element Simulation Of Indentation Test And Crack Propagation Behavior Of Hydrogel

Hydrogels are soft materials where the three dimensional polymer network is immersed in water and may imbibe a large quantity of water. The dual attributes of a solid and a liquid,their environmental sensitivities and other superior properties, make the hydrogel a material of choice in nature and in engineering for a variety of applications, sustained drug delivery, tissue engineering scaffolds and biological sensors. Many hydrogels are mechanically fragile.Thus,it is important to understand the fracture behavior of hydrogels. There was many finite element simulations of hydrogels using rubber-like materials which doesn’t consider the influence of the movement of solution. It is necessary considering the influence of solution to simulate the mechanical behavior of hydrogels.In this paper, we used a mechanics constitutive model which considered the large deformation of the three dimensional polymer network and the movement of solution to simulate hydrogels using a user-defined hyperelastic material in ABAQUS. We investigated that the thickness of hydrogel substance how to affect the value of elastic modulus obtained from indentation experiment, we also discussed the influence of the polymer network and solution in hydrogel on the propagation of edge crack in hydrogel materials and interface crack in the different hydrogel, between hydrogel and elastomer, and between hydrogel and rigid substance.Results of FEM calculation showed that indentation measurements based on Hertz theory overestimate the elastic modulus when hydrogel substance is thin, correction factor presented by RongLong isn’t applicable for our hydrogel’s constitutive model. The initial swellen degree and density of polymer networks of hydrogels which influence the elastic modulus affect the crack fracture of hydrogel. When hydrogel is stretched,solution gathered to the crack tip affects the stress of crack tip and the crack fracture.When the elastic modulus of elastomer is 100 times more than the hydrogels in the interface crack between hydrogel and elastomer, elastomer can be regarded as rigid body.