Department of Biomedical Engineering, Eindhoven University of Technology, Den Dolech 2, Gem-Z. 4.11, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
Department of Biomedical Engineering, Eindhoven University of Technology, Den Dolech 2, Gem-Z. 4.11, P.O. Box 513, 5600 MB Eindhoven, The Netherlands; Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, The Netherlands.
J Mech Behav Biomed Mater. 2018 Oct;86:423-432. doi: 10.1016/j.jmbbm.2018.07.008. Epub 2018 Jul 11.
Skin mechanics is of importance in various fields of research when accurate predictions of the mechanical response of skin is essential. This study aims to develop a new constitutive model for human skin that is capable of describing the heterogeneous, nonlinear viscoelastic mechanical response of human skin under shear deformation. This complex mechanical response was determined by performing large amplitude oscillatory shear (LAOS) experiments on ex vivo human skin samples. It was combined with digital image correlation (DIC) on the cross-sectional area to assess heterogeneity. The skin is modeled as a one-dimensional layered structure, with every sublayer behaving as a nonlinear viscoelastic material. Heterogeneity is implemented by varying the stiffness with skin depth. Using an iterative parameter estimation method all model parameters were optimized simultaneously. The model accurately captures strain stiffening, shear thinning, softening effect and nonlinear viscous dissipation, as experimentally observed in the mechanical response to LAOS. The heterogeneous properties described by the model were in good agreement with the experimental DIC results. The presented mathematical description forms the basis for a future constitutive model definition that, by implementation in a finite element method, has the capability of describing the full 3D mechanical behavior of human skin.
皮肤力学在多个研究领域都具有重要意义，因为准确预测皮肤的力学响应至关重要。本研究旨在开发一种新的人体皮肤本构模型，该模型能够描述剪切变形下人体皮肤的非均相、非线性粘弹性力学响应。通过对离体人体皮肤样本进行大振幅振荡剪切（LAOS）实验，确定了这种复杂的力学响应。结合数字图像相关（DIC）技术对横截面面积进行评估，以评估非均质性。皮肤被建模为一维层状结构，每个子层表现为非线性粘弹性材料。通过改变皮肤深度的刚度来实现非均质性。使用迭代参数估计方法，可以同时优化所有模型参数。该模型准确地捕捉到应变硬化、剪切变稀、软化效应和非线性粘性耗散，与 LAOS 实验观察到的力学响应一致。模型描述的非均质性与实验 DIC 结果吻合较好。所提出的数学描述为未来本构模型定义奠定了基础，通过在有限元方法中的实现，该模型能够描述人体皮肤的全三维力学行为。
