Wang Lei, Hill Nicholas A, Roper Steven M, Luo Xiaoyu
2Department of Engineering, Durham University, Durham, DH1 3LE UK.
1School of Mathematics and Statistics, University of Glasgow, University Place, Glasgow, G12 8QQ UK.
J Eng Math. 2018;109(1):227-238. doi: 10.1007/s10665-017-9948-0. Epub 2017 Dec 13.
An arterial dissection is a longitudinal tear in the vessel wall, which can create a false lumen for blood flow and may propagate quickly, leading to death. We employ a computational model for a dissection using the extended finite element method with a cohesive traction-separation law for the tear faces. The arterial wall is described by the anisotropic hyperelastic Holzapfel-Gasser-Ogden material model that accounts for collagen fibres and ground matrix, while the evolution of damage is governed by a linear cohesive traction-separation law. We simulate propagation in both peeling and pressure-loading tests. For peeling tests, we consider strips and discs cut from the arterial wall. Propagation is found to occur preferentially along the material axes with the greatest stiffness, which are determined by the fibre orientation. In the case of pressure-driven propagation, we examine a cylindrical model, with an initial tear in the shape of an arc. Long and shallow dissections lead to buckling of the inner wall between the true lumen and the dissection. The various buckling configurations closely match those seen in clinical CT scans. Our results also indicate that a deeper tear is more likely to propagate.
动脉夹层是血管壁的纵向撕裂，可形成血液流动的假腔，并可能迅速扩展，导致死亡。我们采用扩展有限元方法并结合撕裂面的内聚牵引力分离定律，构建了动脉夹层的计算模型。动脉壁由考虑了胶原纤维和基质的各向异性超弹性霍尔扎普费尔-加塞尔-奥格登材料模型描述，而损伤的演化由线性内聚牵引力分离定律控制。我们在剥离试验和压力加载试验中模拟了扩展过程。对于剥离试验，我们考虑从动脉壁上切下的条带和圆盘。发现扩展优先沿着刚度最大的材料轴发生，这些轴由纤维取向决定。在压力驱动扩展的情况下，我们研究了一个圆柱形模型，其初始撕裂为弧形。长而浅的夹层会导致真腔和夹层之间的内壁发生屈曲。各种屈曲形态与临床CT扫描中所见的形态非常匹配。我们的结果还表明，更深的撕裂更有可能扩展。
