INVESTIGATIONS OF THE VISCOELASTICITY OF ESOPHAGEAL TISSUE USING INCREMENTAL STRESS-RELAXATION TEST AND CYCLIC EXTENSION TEST

The time-dependent mechanical properties of porcine esophagus were investigated experimentally and theoretically. It was hypothesized that the viscoelasticity was quasi-linear. The incremental stress-relaxation test was conducted to identify the material constants included in the quasi-linear viscoelastic (QLV) model. To verify the predictive ability of the model, the incremental cyclic test was performed. Hysteresis was calculated and compared with that predicted by the model. Results showed that stresses relaxed by 20–30% within the first 10 s and stabilized at 50% at 300 s. The QLV model was shown to be able to describe the viscoelasticity of esophagus across various stretch levels. The model could also predict the hysteresis during cyclic test well. It suggested that the QLV could be used as the material characterization of esophageal tissue.