Taghizadeh Hadi, Tafazzoli-Shadpour Mohammad, Shadmehr Mohammad B, Fatouraee Nasser
Cardiovascular Engineering Laboratory, Faculty of Biomedical Engineering, Amirkabir University of Technology, 424 Hafez Ave., Tehran 15875-4413, Iran.
Tracheal Diseases Research Center, National Research Institute of Tuberculosis and Lung Diseases (NRITLD), ShahidBeheshti University of Medical Sciences, Tehran 19575-154, Iran.
Materials (Basel). 2015 Jan 16;8(1):302-316. doi: 10.3390/ma8010302.
Evaluation of the mechanical properties of arterial wall components is necessary for establishing a precise mechanical model applicable in various physiological and pathological conditions, such as remodeling. In this contribution, a new approach for the evaluation of the mechanical properties of aortic media accounting for the lamellar structure is proposed. We assumed aortic media to be composed of two sets of concentric layers, namely sheets of elastin (Layer I) and interstitial layers composed of mostly collagen bundles, fine elastic fibers and smooth muscle cells (Layer II). Biaxial mechanical tests were carried out on human thoracic aortic samples, and histological staining was performed to distinguish wall lamellae for determining the dimensions of the layers. A neo-Hookean strain energy function (SEF) for Layer I and a four-parameter exponential SEF for Layer II were allocated. Nonlinear regression was used to find the material parameters of the proposed microstructural model based on experimental data. The non-linear behavior of media layers confirmed the higher contribution of elastic tissue in lower strains and the gradual engagement of collagen fibers. The resulting model determines the nonlinear anisotropic behavior of aortic media through the lamellar microstructure and can be assistive in the study of wall remodeling due to alterations in lamellar structure during pathological conditions and aging.
评估动脉壁成分的力学性能对于建立适用于各种生理和病理状况（如重塑）的精确力学模型是必要的。在本论文中，提出了一种考虑层状结构来评估主动脉中膜力学性能的新方法。我们假设主动脉中膜由两组同心层组成，即弹性蛋白片层（第一层）和主要由胶原束、细弹性纤维和平滑肌细胞组成的间质层（第二层）。对人体胸主动脉样本进行了双轴力学测试，并进行了组织学染色以区分壁层板，从而确定各层的尺寸。为第一层分配了新胡克应变能函数（SEF），为第二层分配了四参数指数SEF。基于实验数据，使用非线性回归来寻找所提出的微观结构模型的材料参数。中膜层的非线性行为证实了弹性组织在低应变下的贡献更大，以及胶原纤维的逐渐参与。所得模型通过层状微观结构确定了主动脉中膜的非线性各向异性行为，并且有助于研究病理状况和衰老过程中层状结构改变导致的壁重塑。
