Related Experiment Video
Updated: Jun 24, 2026

Biomechanical Characterization of Human Soft Tissues Using Indentation and Tensile Testing
Published on: December 13, 2016
Viscoelastic relaxation and recovery of tendon
Sarah E Duenwald1, Ray Vanderby, Roderic S Lakes
1Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI 53706-1687, USA. duenwald@wisc.edu
Abstract:
Tendons exhibit complex viscoelastic behaviors during relaxation and recovery. Recovery is critical to predicting behavior in subsequent loading, yet is not well studied. Our goal is to explore time-dependent recovery of these tendons after loading. As a prerequisite, their strain-dependent viscoelastic behaviors during relaxation were also characterized. The porcine digital flexor tendon was used as a model of tendon behavior. Strain-dependent relaxation was observed in tests at 1, 2, 3, 4, 5, and 6% strain. Recovery behavior of the tendon was examined by performing relaxation tests at 6%, then dropping to a low but nonzero strain level. Results show that the rate of relaxation in tendon is indeed a function of strain. Unlike previously reported tests on the medial collateral ligament (MCL), the relaxation rate of tendons increased with increased levels of strain. This strain-dependent relaxation contrasts with quasilinear viscoelasticity (QLV), which predicts equal time dependence across various strains. Also, the tendons did not recover to predicted levels by nonlinear superposition models or QLV, though they did recover partially. This recovery behavior and behavior during subsequent loadings will then become problematic for both quasilinear and nonlinear models to correctly predict.
Related Concept Videos
Relaxation of Skeletal Muscles
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open.
Plastic Behavior
Elastin is Responsible for Tissue Elasticity
Ligaments and tendons are made of dense regular connective tissue, but in ligaments not all fibers are parallel. Dense regular elastic tissue contains elastin fibers and...
Residual Stresses in Bending
Elasticity
The elasticity of an object can be described by a stress-strain curve, which represents the relationship between stress...
Strain and Elastic Modulus
