The airways and parenchyma of lung experience large deformations during normal respiration. Spatially accurate predictions of airflow patterns and aerosol transport therefore require respiration to be modeled as a fluid–structure interaction problem. Such computational models in turn require constitutive models for the parencyhma that are both accurate and efficient. Herein, an implicit theory of elasticity is derived from thermodynamics to meet this need, leading to a generic template for strain-energy that is shown to be an exact analogue for the well-known Fung model that is the root of modern constitutive theory of tissues. To support this theory, we also propose a novel definition of Lagrangian strain rate. Unlike the classic definition of Lagrangian strain rate, this new definition is separable into volumetric and deviatoric terms, a separation that is both mathematically and physically justified. Within this framework, a novel material model capable of describing the elastic contribution of the nonlinear response of parenchyma is constructed and characterized against published data.

在正常呼吸过程中，肺的气道和实质会发生较大的变形。因此，对气流模式和气溶胶传输的空间准确预测需要将呼吸建模为流固耦合问题。这样的计算模型反过来需要准确和高效的parencyhma 本构模型。在这里，从热力学中推导出了一个隐含的弹性理论以满足这一需求，导致应变能的通用模板被证明是众所周知的 Fung 模型的精确模拟，该模型是现代组织本构理论的根源. 为了支持这一理论，我们还提出了拉格朗日应变率的新定义。与拉格朗日应变率的经典定义不同，这个新定义可分为体积项和偏项项，一种在数学上和物理上都是合理的分离。在此框架内，构建了一种能够描述薄壁组织非线性响应的弹性贡献的新型材料模型，并根据已发布的数据对其进行表征。