Experimental Evaluation of Fiber Orientation Based Material Properties of Skeletal Muscle in Tension

Biomechanical researches are essential to develop new techniques to improve the clinical relevance. Skeletal muscle generates the force which results in the motion of human body, so it is essential to study the mechanical and structural properties of skeletal muscle. Many researchers have carried out mechanical study of skeletal muscle with in-vivo testing. This work aims to examine anisotropic mechanical behavior of skeletal muscle with in vitro test (tensile test). It is important to understand the mechanical and structural behavior of skeletal muscle when it is subjected to external loading; the research aims to determine the structural properties of skeletal muscle by tensile testing. Tensile testing is performed on 5 samples of skeletal muscle of a goat at the rate of 1mm/min with fiber orientation along the length and 45 degrees inclined to the length. It is found that muscle is stiffer in the direction parallel to the muscle fiber than at 45 degrees to the muscle fibers. The tensile strength of the skeletal muscle along the fiber direction is 0.44 MPa at maximum load of 110 N and for direction 45 degrees inclined to the muscle fibers, the strength is 0.234 MPa at max load 43 N. The displacement of Muscle sample against the maximum load is small along the length of the muscle fiber i.e. under longitudinal elongation [15.257 mm] as compared to 45 degrees inclined to the length of skeletal muscle [17.775 mm] and under cross fiber elongation [19.7291mm by FEA]. The testing is not performed for 90 degrees fiber orientation due to unavailability of soft tissue in cross fiber direction of the required specification, but finite element analysis is done on the skeletal muscle for the cross fiber orientation. As the fiber orientation within skeletal muscle differs with respect to the length of the muscle, the stiffness of skeletal muscle is also changing effectively. Hence skeletal muscle exhibits the anisotropic mechanical behavior.