Failure of the porcine ascending aorta: Multidirectional experiments and a unifying microstructural model

Colleen M. Witzenburg, Rohit Y. Dhume, Sachin B. Shah, Christopher E. Korenczuk, Hallie P. Wagner, Patrick W. Alford, Victor H. Barocas

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

The ascending thoracic aorta is poorly understood mechanically, especially its risk of dissection. To make better predictions of dissection risk, more information about the multidimensional failure behavior of the tissue is needed, and this information must be incorporated into an appropriate theoretical/computational model. Toward the creation of such a model, uniaxial, equibiaxial, peel, and shear lap tests were performed on healthy porcine ascending aorta samples. Uniaxial and equibiaxial tests showed anisotropy with greater stiffness and strength in the circumferential direction. Shear lap tests showed catastrophic failure at shear stresses (150-200 kPa) much lower than uniaxial tests (750-2500 kPa), consistent with the low peel tension (60 mN/mm). A novel multiscale computational model, including both prefailure and failure mechanics of the aorta, was developed. The microstructural part of the model included contributions from a collagenreinforced elastin sheet and interlamellar connections representing fibrillin and smooth muscle. Components were represented as nonlinear fibers that failed at a critical stretch. Multiscale simulations of the different experiments were performed, and the model, appropriately specified, agreed well with all experimental data, representing a uniquely complete structure-based description of aorta mechanics. In addition, our experiments and model demonstrate the very low strength of the aorta in radial shear, suggesting an important possible mechanism for aortic dissection.

Original languageEnglish (US)
Article number031005
JournalJournal of biomechanical engineering
Volume139
Issue number3
DOIs
StatePublished - Mar 1 2017

Bibliographical note

Publisher Copyright:
Copyright © 2017 by ASME.

Keywords

  • Biomechanics
  • Failure
  • Peel
  • Shear

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