Abstract

Characterizing the rheological properties of liver tissue, especially within the linear viscoelastic region, is useful for investigating the behaviour of the tissue under mechanical loads. This paper reports three types of experiments of rheological properties of liver tissue that were carried out recently, including strain sweep oscillation, shear stress relaxation and strain controlled oscillation. These experiments were designed to investigate the following: a) the domain of linear viscoelasticity of liver tissue, b) the time dependent behavior of liver tissue, and c) the dynamic storage modulus and loss modulus. Fresh bovine liver tissues were used for the experiments. All the liver tissues were bathed in a 0.9% sodium chloride solution immediately after harvesting. The test samples were cut to a disk of diameter 20–30mm with 1.5–2.5mm thick. Several strain sweep oscillation tests were performed to measure the sample behavior at stepwise changing strain amplitude at 1 Hz frequency. The results showed that the linear viscoelastic limit of bovine liver tissue is of the order of 0.2% strain. The shear stress relaxation test indicated that there is no apparent long-term elastic modulus reached before 3000 seconds within the linear viscoelastic region. The dynamic storage modulus and loss modulus were obtained in the frequency range of 0.001–20 Hz.

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