We present a framework for considering the gradual recruitment of collagen fibers in hyperelastic constitutive modeling. An effective stretch, which is a response variable representing the true stretch at the tissue-scale, is introduced. Properties of the effective stretch are discussed in detail. The effective stretch and strain invariants derived from it are used in selected hyperelastic constitutive models to describe the tissue response. This construction is investigated in conjunction with Holzapfel-Gasser-Ogden family strain energy functions. The ensuing models are validated against a large body of uniaxial and bi-axial stress–strain response data from human aortic aneurysm tissues. Both the descriptive and the predictive capabilities are examined. The former is evaluated by the quality of constitutive fitting, and the latter is assessed using finite element simulation. The models significantly improve the quality of fitting, and reproduce the experiment displacement, stress, and strain distributions with high fidelity in the finite element simulation.

我们提出了一个框架，用于考虑在超弹性本构建模中逐渐募集胶原纤维。引入了有效拉伸，它是代表组织尺度上真实拉伸的响应变量。详细讨论了有效拉伸的性质。从中得出的有效拉伸和应变不变量用于选定的超弹性本构模型来描述组织响应。这种结构与 Holzapfel-Gasser-Ogden 族应变能函数一起研究。随后的模型针对来自人体主动脉瘤组织的大量单轴和双轴应力应变响应数据进行了验证。检查描述性和预测性能力。前者以本构拟合的好坏来评价，后者使用有限元模拟进行评估。这些模型显着提高了拟合质量，并在有限元模拟中以高保真度再现了实验位移、应力和应变分布。