Latorre Marcos, Montáns Francisco J
Escuela Técnica Superior de Ingeniería Aeronáutica y del Espacio, Universidad Politécnica de Madrid, Plaza Cardenal Cisneros, 3, Madrid 28040, Spain e-mail: .
J Biomech Eng. 2017 Oct 1;139(10). doi: 10.1115/1.4037405.
Soft connective tissues sustain large strains of viscoelastic nature. The rate-independent component is frequently modeled by means of anisotropic hyperelastic models. The rate-dependent component is usually modeled through linear rheological models or quasi-linear viscoelastic (QLV) models. These viscoelastic models are unable, in general, to capture the strain-level dependency of the viscoelastic properties present in many viscoelastic tissues. In linear viscoelastic models, strain-level dependency is frequently accounted for by including the dependence of multipliers of Prony series on strains through additional evolution laws, but the determination of the material parameters is a difficult task and the obtained accuracy is usually not sufficient. In this work, we introduce a model for fully nonlinear viscoelasticity in which the instantaneous and quasi-static behaviors are exactly captured and the relaxation curves are predicted to a high accuracy. The model is based on a fully nonlinear standard rheological model and does not necessitate optimization algorithms to obtain material parameters. Furthermore, in contrast to most models used in modeling the viscoelastic behavior of soft tissues, it is valid for the large deviations from thermodynamic equilibrium typically observed in soft tissues.
软结缔组织能承受具有粘弹性的大应变。与速率无关的部分通常通过各向异性超弹性模型来建模。与速率相关的部分通常通过线性流变模型或准线性粘弹性（QLV）模型来建模。一般来说，这些粘弹性模型无法捕捉许多粘弹性组织中存在的粘弹性特性的应变水平依赖性。在线性粘弹性模型中，应变水平依赖性通常通过普龙级数的乘数对应变的依赖性，并通过额外的演化定律来考虑，但材料参数的确定是一项艰巨的任务，而且所获得的精度通常也不够。在这项工作中，我们引入了一个完全非线性粘弹性模型，该模型能精确捕捉瞬时和准静态行为，并能高精度地预测松弛曲线。该模型基于一个完全非线性标准流变模型，无需优化算法来获取材料参数。此外，与大多数用于模拟软组织粘弹性行为的模型不同，它对于软组织中通常观察到的与热力学平衡的大偏差是有效的。
