Location Dependent Mechanical Behavior of Aponeurosis Tissue Under Uniaxial Tensile Stretch
Emily Tully ’21
Benjamin Wheatley, Mechanical Engineering
Engineering Data Generation Grant
Aponeurosis is a connective tissue that serves as an extension of tendon, attaching to muscle fibers that do not fully extend to the tendon. The material properties of aponeurosis – and thus its mechanical function in the body – are poorly understood. The goal of this work was to perform uniaxial tensile testing to measure the mechanical response of aponeurosis tissue as a function of thickness and location from tendon to muscle. Ten samples measuring ~60mm by 10mm were cut with tissue fibers running lengthwise, and the thickness was measured every 5mm. Uniaxial tensile testing was completed on a custom planar biaxial material testing system with digital image correlation (DIC) to track sample strain. The average nominal (engineering) stress and Lagrange strain values were determined for two regions: the thinner section that connects to muscle fibers and the thicker section that connects to the tendon tissue. Linearized moduli were determined at each time point by dividing nominal stress by Lagrange strain. Paired t-tests (p<0.05) were performed on the Lagrange strain and linearized moduli at each time point. Statistical results indicated that there is no significant difference in the strain of an aponeurosis sample at different thicknesses, but that under greater tensile loads, aponeurosis may exhibit higher moduli corresponding to thinner sections. These results show the material properties of aponeurosis tissue are inhomogeneous and can be used to develop more accurate simulations of muscle-tendon unit mechanical function. Such simulations provide necessary insight into how healthy versus impaired muscle drives the movement of vertebrates.