Nonlinear viscous behavior of the tendon's fascicles from the homogenization of viscoelastic collagen fibers

Investigating the Effect of Aging on the Viscosity of Tendon Fascicles and Fibers

“…The fibrous, matrix-embeded structure of fascicles and fibers (Figure 1A) (Ge et al, 2018) has allowed for the tendon subunits to be characterized as naturally architected, two-phase composite materials (Maceri et al, 2012). The fibrillar components are in a certain relative density to the embedding matrix substance, so that a unit-cell with a fibrous fraction f r can be defined (Figure 1B) (Ganghoffer et al, 2016; Karathanasopoulos et al, 2017, 2019).…”

“…Each material phase can be considered to be in the general case of viscoelastic nature, with elastic and viscous properties E f , E m and η f , η m for the fibrillar and matrix components accordingly. As such, the effective homogenized viscoelastic response of the matrix embedded tendon fibers is characterized by the following constitutive equation (Ganghoffer et al, 2016; Karathanasopoulos et al, 2019):…”

“…Where in Equation (1), components with a bar stand for the homogenized strain and stress trueε¯ and trueσ¯, while brackets for the homogenized elastic and viscous moduli, 〈 E 〉 and 〈η〉 accordingly. The latter depend on the volumetric fraction of the two phases, as follows (Ganghoffer et al, 2016):…”

Exploiting Viscoelastic Experimental Observations and Numerical Simulations to Infer Biomimetic Artificial Tendon Fiber Designs

“…A part of the low efficiency of current restoration practices needs to be attributed to the rather limited understanding of the tendon's inner material properties (Kuo et al, 2010), in particular with respect to its viscoelastic properties (Ganghoffer et al, 2016). The latter depend both on the physiology and on the loading type applied (e.g., quasi-static, high strain rate) (Oftadeh et al, 2018; Wu et al, 2018; Kuznetsov et al, 2019).…”

“…The latter depend both on the physiology and on the loading type applied (e.g., quasi-static, high strain rate) (Oftadeh et al, 2018; Wu et al, 2018; Kuznetsov et al, 2019). The use of biocompatible materials, which mimic the physiological functionality of the native tissue constitutes a key aspect for any tendon restoration process (Ganghoffer et al, 2016). During the last years, substantial efforts have been devoted to the engineering of novel biomaterials with enhanced structural performance and improved biochemical compatibility (Zhang et al, 2017; Li et al, 2018a,b; Li S. et al, 2018; Liu et al, 2018).…”