Department of Mechanical and Industrial Engineering, Center for Computer Aided Design, The University of Iowa, Iowa City, IA 52242, USA.
Ann Biomed Eng. 2010 Feb;38(2):478-89. doi: 10.1007/s10439-009-9839-2. Epub 2009 Nov 21.
Stress analyses of patient-specific vascular structures commonly assume that the reconstructed in vivo configuration is stress free although it is in a pre-deformed state. We submit that this assumption can be obviated using an inverse approach, thus increasing accuracy of stress estimates. In this paper, we introduce an inverse approach of stress analysis for cerebral aneurysms modeled as nonlinear thin shell structures, and demonstrate the method using a patient-specific aneurysm. A lesion surface derived from medical images, which corresponds to the deformed configuration under the arterial pressure, is taken as the input. The wall stress in the given deformed configuration, together with the unstressed initial configuration, are predicted by solving the equilibrium equations as opposed to traditional approach where the deformed geometry is assumed stress free. This inverse approach also possesses a unique advantage, that is, for some lesions it enables us to predict the wall stress without accurate knowledge of the wall elastic property. In this study, we also investigate the sensitivity of the wall stress to material parameters. It is found that the in-plane component of the wall stress is indeed insensitive to the material model.
尽管重建的体内结构处于预变形状态，但针对特定患者的血管结构的应力分析通常假设该结构处于无应力状态。我们提出可以使用反演方法来避免这种假设，从而提高应力估计的准确性。在本文中，我们引入了一种针对作为非线性薄壳结构建模的脑动脉瘤的应力分析反演方法，并使用一个特定患者的动脉瘤对该方法进行了演示。取自医学图像的病变表面，对应于动脉压下的变形构型，被用作输入。通过求解平衡方程来预测给定变形构型中的壁应力，以及无应力的初始构型，这与传统方法不同，传统方法假设变形几何形状是无应力的。这种反演方法还有一个独特的优势，即对于某些病变，它使我们能够在不了解壁弹性特性的情况下预测壁应力。在本研究中，我们还研究了壁应力对材料参数的敏感性。结果发现，壁应力的面内分量确实对材料模型不敏感。
