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Biomechanics of Arterial Walls under Supra-Physiological Loading Conditions

超生理负荷条件下动脉壁的生物力学

基本信息

批准号：
166835325
负责人：
Professor Dr.-Ing. Daniel Balzani
金额：
--
依托单位：
Institut für Biomechanik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2010
资助国家：
德国
起止时间：
2009-12-31 至 2016-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/166835325?language=en
关键词：
Biomechanics Arterial Walls under Supra

项目摘要

In this research project supra-physiological loading situations of arterial walls, e.g., occurring during balloon angioplasty, are described. Under such loading conditions microscopic damage on the interfibrillar level is induced in the tissue leading to a complex softening hysteresis observed in the stress-strain response. To describe this behavior, damage models were developed in the first phase of this project on the basis of continuum damage mechanics. These models were compared with experiments and a good correlation could be shown. However, the loss of ellipticity, which is typically observed for damage mechanics formulations, may lead to mesh-dependent solutions and the loss of material stability. In order to solve these substantial fundamental problems, mathematically secured and robust modeling approaches are central task in this second phase. The basis is the construction of an incremental variational formulation for damage in soft biological tissues which enables convexification. Thereby, the loss of ellipticity can be precluded and mesh-independent solutions as well as material stability are ensured. Essentially, efficient models and algorithms are planned to be developed on the basis of relaxed incremental variational formulations, which reflect the specific characteristics of the damage hysteresis in soft biological tissues. Starting from a rather phenomenological but efficient approach which is to be constructed first, a model has to be developed, which takes into account fiber dispersion. Thereby damage evolution is described by a progressive recruitment of individual fiber orientations. In order to enable an optimized parameter adjustment in the sense of a least-square minimization in reasonable time also for this model, a surrogate model is planned to be constructed and used during parameter optimization. The developed formulations have to be implemented in a finite-element program. Then they have to be analyzed with respect to their performance on the basis of boundary value problems where diseased arterial walls are simulated.

在该研究项目中，描述了动脉壁的超生理负荷情况，例如在球囊血管成形术期间发生的情况。在这种负载条件下，组织中会引起原纤维间水平的微观损伤，导致在应力应变响应中观察到复杂的软化滞后。为了描述这种行为，该项目的第一阶段在连续损伤力学的基础上开发了损伤模型。将这些模型与实验进行比较，可以显示出良好的相关性。然而，通常在损伤力学公式中观察到的椭圆度损失可能会导致依赖于网格的解决方案和材料稳定性的损失。为了解决这些实质性的基本问题，数学上安全且稳健的建模方法是第二阶段的中心任务。其基础是构建用于软生物组织损伤的增量变分公式，从而实现凸化。因此，可以防止椭圆度的损失，并确保独立于网格的解决方案以及材料稳定性。本质上，计划在宽松增量变分公式的基础上开发有效的模型和算法，反映软生物组织损伤滞后的具体特征。从首先要构建的相当现象学但有效的方法开始，必须开发一个考虑光纤色散的模型。因此，损伤演变是通过单个纤维方向的逐渐恢复来描述的。为了使该模型能够在合理的时间内进行最小二乘最小化意义上的优化参数调整，计划在参数优化期间构建和使用代理模型。开发的公式必须在有限元程序中实施。然后，必须根据模拟患病动脉壁的边值问题来分析它们的性能。