Soft-tissue viscoelasticity: extension to anisotropy and finite element implementation

Physiological loading result to finite and finite rate of deformations of soft tissues such as ligament, tendons, and the annulus fibrosus of the intervertebral disc. Under these conditions, these soft tissues exhibit viscoelastic effects such as strain-stiffening, creep and relaxation that have important implications in the stability of joints. Although the effects are significant, viscoelasticity has, however, only recently been taken into account in biomechanical studies. We have developed a versatile viscoelastic model for soft tissues that requires some extensions. The model is currently limited to isotropy. Therefore, this project consists in extending and implementing (ABAQUS) soft tissue anisotropy usually found in soft tissues.