Study on nonlinear constitutive model of skin under compression load over a wide range of strain rates

Abstract

Purpose: In wound ballistics, skin has obvious blocking effect in the biological target penetration of projectiles. An analytical description of skin mechanical properties under compression can set the basis for the numerical simulation and the evaluation of blocking effect. Methods: In this study, an improved three-parameter solid visco-elastic model was proposed to describe the skin creep phenomenon. And then combined with Maxwell and Ogden model, a new nonlinear skin constitutive model, consisting of hyper-elastic unit, creep unit and relaxation unit in parallel, was established. Here, we examine the material properties of freshly harvested porcine skin in compression at strain rates from 0.01/s to 4000/s. Results: The model is verified by comparison with the experimental results by our test and that in the literature at different strain rates. Conclusions: It shows that calculated results of the constitutive model agree well with the experiment data at extremely low to high strain rates, which is useful for the description of the heterogeneous, nonlinear viscoelastic, relaxation and creep mechanical response of skin under compression.