Materials science

Social psychology

Hyperelastic material

Constitutive equation

Stress relaxation

Viscoelasticity

Classical mechanics

Creep

Thermodynamics

Physics

Finite element method

Psychology

Relaxation (psychology)

Strain energy

Composite material

Compression (physics)

Mechanics

Ogden

Strain rate

International Journal of Applied Mechanics

The mechanical behavior of very soft tissues, such as liver, brain, kidney, etc. is assumed to be viscohyperelastic. The conventional approaches like quasi-linear viscoelastic (QLV) are limited to low strain rates and are unable to capture the short-term memory effects. In this paper, a new viscohyperelastic constitutive model is presented in which the strain energy function is decomposed into an elastic and a viscous part. The elastic part of the strain energy is assumed as a Mooney–Rivlin model, while a new viscous potential, as a function of strain and its rate, is proposed. Unconfined uniaxial compression tests are conducted up to 10% compression at two loading velocities of 1.3 and 10.56[Formula: see text](mm/min), to determine the material constants. A numerical simulation is also used to investigate the model-predicted material behavior. It is shown that the model is more sensitive to the hyperelastic parameters than the viscous parameters. This model is also able to predict the stress relaxation and hysteresis; however, an instantaneous relaxation is observed.

A New Viscous Potential Function for Developing the Viscohyperelastic Constitutive Model for Bovine Liver Tissue: Continuum Formulation and Finite Element Implementation