A Phase-field Approach to Model Aortic Dissections


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Gültekin O., Dal H. , Holzapfel G. A.

ESMC 2018 10th European Solid Mechanics Conference, Bologna, İtalya, 2 - 06 Temmuz 2018, ss.1

  • Basıldığı Şehir: Bologna
  • Basıldığı Ülke: İtalya
  • Sayfa Sayıları: ss.1

Özet

Physiological and pathological aspects of aortic dissection are important issues in medical science , and undoubtedly require a deeper understanding of the respective mechanics that is behind these phenomenon. This has rendered computational mechanics very important to improve and even guide monitoring and preoperative planning [1]. In particular, the in silico estimation of the macro-scopic crack initiation and its propagation associated with aortic dissection purports valuable data for the clinics. The present study, developed on the basis of the variational principle, features a thermodynam-ically consistent, gradient-type, diffusive crack phase-field approach to fracture. The constitutive model is essentially anisotropic in accordance with the tissue morphology. A novel anisotropic phase-field model not only takes the geometric effect into account, it also allows for the distinct strain-energy contributions of isotropic and anisotropic parts into the failure criterion [2, 3]. On the spatial side, a canonical Galerkin-type finite element procedure, together with a standard discretization, yields the algebraic counterparts of the weighted residual expressions and the symmetric tangent matrices. Subsequently, the partition of the monolithic solution scheme on the temporal side successively updates the history field described by the failure Ansatz, the crack phase-field and the deformation field [2, 3]. Finally, we numerically analyze benchmark boundary-value problems, i.e. peel tests of the tho-racic aortic media, and novel simple concepts of design such as an idealized cylindrical model of the multi-layered thoracic aortic wall with a notch representing the incipient mechanical degeneration, and another idealized cylindrical model with an initial tear pertaining to the nascent false lumen. Those novel numerical investigations, albeit rather scarce as yet, may well be recovered by ex vivo experiments.