Mechanical behavior measurement of the sheep small intestine using experimental tests

There is no consistent data on the mechanical properties of sheep intestine.
We performed a series of biaxial strain measurement experiments and extracted the constitutive model to describe the mechanical characteristics of the sheep intestinal tissue.
Eleven specimens were obtained freshly from sacrificed sheep and the planar biaxial tests were performed on the tissue specimens by applying simultaneous loads along the circumfer-ential and longitudinal directions. Then the measured data were fitted into the anisotropic four-parameter Fung-type model and also to the modified Mooney-Rivlin model.
The specimens showed some degree of anisotropy; the stiffer direction is not gener-ally predictable. Some of the specimens were stiffer in the circumferential direction, and the others in the longitudinal direction. However, the average results state the circumferential di-rection as the stiffer orientation.
It can be concluded that sheep intestine be-haves normally as a nonlinear anisotropic tissue which is well-characterized by the modified Mooney-Rivlin model.