The effects of cyclic tensile and stress-relaxation tests on porcine skin

Abstract

When a living tissue is subjected to cyclic stretching, the stress-strain curves show a shift down with the increase in the number of cycles until stabilization. This phenomenon is referred to in the literature as a preconditioning and is performed to obtain repeatable and predictable measurements. Preconditioning has been routinely performed in skin tissue tests; however, its effects on the mechanical properties of the material such as viscoelastic response, tangent modulus, sensitivity to strain rate, the stress relaxation rate, etc….remain unclear. In addition, various physical interpretations of this phenomenon have been proposed and there is no general agreement on its origin at the microscopic or mesoscopic scales. The purpose of this study was to investigate the effect of the cyclical stretching and the stress-relaxation tests on the mechanical properties of the porcine skin. Cyclic uniaxial tensile tests at large and constant strain were performed on different skin samples. The change in the reaction force, and skin's tangent modulus as a function of the number of cycles, as well as the strain rate effect on the mechanical behavior of skin samples after cycling were investigated. Stress-relaxation tests were also performed on skin samples. The change in the reaction force as a function of relaxation time and the strain rate effect on the mechanical behavior of skin samples after the stress-relaxation were investigated. The mechanical behavior of a skin sample under stress-relaxation test was modeled using a combination of hyperelasticity and viscoelasticity. Overall, the results showed that the mechanical behavior of the skin was strongly influenced by cycling and stress relaxation tests. Indeed, it was observed that the skin's resistance decreased by about half for two hours of cycling; the tangent modulus degraded by nearly 30% and skin samples became insensitive to the strain rates and accumulated progressively an inelastic deformation over time during cycling. Finally, the hysteresis loops became very narrow at the end of cycling and after relaxation process.

Modeling the nonlinear elastic behavior of plant epidermis

“…However, comparing the ultimate strength from monotonic tensile tests of the samples did not confirm this. Particularly, if the net orientation of cellulose was in the longitudinal direction, the samples excised in this direction were expected to exhibit a considerably higher ten- (Remache et al 2018) 0.69 23.2 0 Human epidermis (Groves et al 2012) 4.099 2.98 0 Human dermis (Groves et al 2012) 0.022 3.28 0 Porcine cortex (Coats and Margulies 2006) 167e -6 0.013 0 Note: Values for D 1 were not included in the optimization process for onion epidermis, and the material was considered nearly incompressible. sile strength than those prepared in the perpendicular direction to the mean cellulose orientation.…”

Stress-Relaxation and Cyclic Behavior of Human Carotid Plaque Tissue

“…Recorded load and displacement data were analyzed to quantify the changes in mechanical properties over time (Remache et al, 2018). Eight carotid plaque strips were subjected to a stress-relaxation test at a strain rate of 0.1 and 1 mm/s (4 samples each).…”

“…Therefore, understanding the mechanical response of the plaque tissue using stress-relaxation and cyclic stretching is beneficial in designing disease treatment and management procedures. However, investigations that characterize the mechanical behavior of carotid plaques under cyclic loading conditions and the viscoelastic properties remains relatively unexplored, except a few studies on arterial elastin, porcine veins and arteries, abdominal aortic aneurysm, ligaments, muscle and skin tissues (Fung, 1967;Salunke et al, 2001;Toms et al, 2002;Sarver et al, 2003;Gasser et al, 2008;Heiland et al, 2013;Pasquesi et al, 2016, Pasquesi andMargulies, 2017;Remache et al, 2018;Wang et al, 2018;Yoo et al, 2009;Zou and Zhang, 2011).…”

The effects of topical liposomal resveratrol on incisional and excisional wound healing process

“…For this reason, it has been preferred as a reference molecule in many studies including our study. In many previous studies, the tensile strength was measured to determine the amount of improvement in the skin tissue in incisional wound healing 32 . In addition to the parameters examined in previous studies, we aimed to obtain more data by measuring the parameters of maximum load, stress, strain, and elongation on the healing of incisional wound tissue in our study.…”