LAUSR

A polymeric gel contains a crosslinked polymer network and solvent. Gels can swell or shrink in response to external stimuli. Two kinetic processes are usually involved during the deformation of gels: the viscoelastic and poroelastic responses. Viscoelasticity of gels is generated from the local rearrangement of the polymers, while poroelasticity of gels is generated from the solvent migration. The coupled time-dependent behaviors of gels can be formulated by coupling a rheological spring-dashpot model with a diffusion-deformation model of gels. In this work, we build a general framework of coupled visco-poroelasticity for transversely isotropic gels and study how the mechanical anisotropy could induce anisotropic time-dependent behaviors of gels even though their kinetic properties are isotropic. The constitutive model is implemented into a finite element code in commercial software. Several numerical simulations are performed to investigate the time-dependent deformation and frequency-dependent energy dissipation under different loading directions. The results show that even though the viscoelasticity and the poroelasticity are isotropic, the time-dependent behaviors along different directions are different due to the mechanical anisotropy. The fibers aligned in the transversely isotropic gel enhance the elastic feature of the material, and thus influence the dissipation time scales and the amount of energy loss for both viscoelasticity and poroelasticity.