Modeling fatigue failure in soft tissue using a visco-hyperelastic model with discontinuous damage

Area of Science:

• Biomechanics
• Materials Science
• Tissue Engineering

Background:

• Soft tissues are vulnerable to injuries from both single high-impact loads and repeated low-impact fatigue loads.
• Existing models effectively simulate static failure but lack robust frameworks for fatigue failure in soft tissues.

Purpose of the Study:

• To assess the feasibility of a visco-hyperelastic damage model with discontinuous damage for simulating fatigue failure in soft fibrous tissue.
• To establish a unified constitutive formulation capable of modeling both static and fatigue failure behaviors.

Main Methods:

• Utilized a visco-hyperelastic damage model with a strain energy-based damage criterion.
• Calibrated specimen-specific material parameters using cyclic creep data from uniaxial tensile fatigue experiments on human medial meniscus.
• Validated the model's ability to simulate static failure using parameters derived from fatigue experiments.

Main Results:

• The model accurately simulated the three characteristic stages of cyclic creep and predicted tissue rupture cycles.
• Demonstrated that damage propagation under cyclic stress is driven by time-dependent viscoelastic increases in stretch and strain energy.
• Showcased the model's capability to replicate static failure stress-strain curves.

Conclusions:

• A visco-hyperelastic discontinuous damage framework can effectively model cyclic creep and predict rupture in soft tissues.
• Solid viscoelasticity is a key factor regulating fatigue failure, with slower stress relaxation times conferring greater resistance.
• This unified model offers a reliable approach for simulating both fatigue and static failure in soft tissues.