Mechanical strength of aneurysmatic and dissected human thoracic aortas at different shear loading modes

Gerhard Sommer, Selda Mitatova Sherifova, Peter J Oberwalder, Otto E Dapunt, Patricia A Ursomanno, Abe DeAnda, Boyce E Griffith, Gerhard Holzapfel

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Rupture of aneurysms and acute dissection of the thoracic aorta are life-threatening events which affect tens of thousands of people per year. The underlying mechanisms remain unclear and the aortic wall is known to lose its structural integrity, which in turn affects its mechanical response to the loading conditions. Hence, research on such aortic diseases is an important area in biomechanics. The present study investigates the mechanical properties of aneurysmatic and dissected human thoracic aortas via triaxial shear and uniaxial tensile testing with a focus on the former. In particular, ultimate stress values from triaxial shear tests in different orientations regarding the aorta׳s orthotropic microstructure, and from uniaxial tensile tests in radial, circumferential and longitudinal directions were determined. In total, 16 human thoracic aortas were investigated from which it is evident that the aortic media has much stronger resistance to rupture under 'out-of-plane' than under 'in-plane' shear loadings. Under different shear loadings the aortic tissues revealed anisotropic failure properties with higher ultimate shear stresses and amounts of shear in the longitudinal than in the circumferential direction. Furthermore, the aortic media decreased its tensile strength as follows: circumferential direction >longitudinaldirection> radial direction. Anisotropic and nonlinear tissue properties are apparent from the experimental data. The results clearly showed interspecimen differences influenced by the anamnesis of the donors such as aortic diseases or connective tissue disorders, e.g., dissected specimens exhibited on average a markedly lower mechanical strength than aneurysmatic specimens. The rupture data based on the combination of triaxial shear and uniaxial extension testing are unique and build a good basis for developing a 3D failure criterion of diseased human thoracic aortic media. This is a step forward to more realistic modeling of mechanically induced tissue failure i.e. rupture of aneurysms or progression of aortic dissections.

Original languageEnglish
Pages (from-to)2374-82
Number of pages9
JournalJournal of biomechanics
Volume49
Issue number12
DOIs
Publication statusPublished - 16 Aug 2016

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Thoracic Aorta
Strength of materials
Rupture
Tissue
Dissection
Aortic Diseases
Aneurysm
Thoracic Diseases
Biomechanics
Tensile Strength
Tensile testing
Structural integrity
Biomechanical Phenomena
Connective Tissue
Aorta
Shear stress
Tensile strength
Mechanical properties
Microstructure
Direction compound

Keywords

  • Journal Article

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Mechanical strength of aneurysmatic and dissected human thoracic aortas at different shear loading modes. / Sommer, Gerhard; Sherifova, Selda Mitatova; Oberwalder, Peter J; Dapunt, Otto E; Ursomanno, Patricia A; DeAnda, Abe; Griffith, Boyce E; Holzapfel, Gerhard.

In: Journal of biomechanics, Vol. 49, No. 12, 16.08.2016, p. 2374-82.

Research output: Contribution to journalArticleResearchpeer-review

Sommer, Gerhard ; Sherifova, Selda Mitatova ; Oberwalder, Peter J ; Dapunt, Otto E ; Ursomanno, Patricia A ; DeAnda, Abe ; Griffith, Boyce E ; Holzapfel, Gerhard. / Mechanical strength of aneurysmatic and dissected human thoracic aortas at different shear loading modes. In: Journal of biomechanics. 2016 ; Vol. 49, No. 12. pp. 2374-82.
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T1 - Mechanical strength of aneurysmatic and dissected human thoracic aortas at different shear loading modes

AU - Sommer, Gerhard

AU - Sherifova, Selda Mitatova

AU - Oberwalder, Peter J

AU - Dapunt, Otto E

AU - Ursomanno, Patricia A

AU - DeAnda, Abe

AU - Griffith, Boyce E

AU - Holzapfel, Gerhard

N1 - Copyright © 2016 Elsevier Ltd. All rights reserved.

PY - 2016/8/16

Y1 - 2016/8/16

N2 - Rupture of aneurysms and acute dissection of the thoracic aorta are life-threatening events which affect tens of thousands of people per year. The underlying mechanisms remain unclear and the aortic wall is known to lose its structural integrity, which in turn affects its mechanical response to the loading conditions. Hence, research on such aortic diseases is an important area in biomechanics. The present study investigates the mechanical properties of aneurysmatic and dissected human thoracic aortas via triaxial shear and uniaxial tensile testing with a focus on the former. In particular, ultimate stress values from triaxial shear tests in different orientations regarding the aorta׳s orthotropic microstructure, and from uniaxial tensile tests in radial, circumferential and longitudinal directions were determined. In total, 16 human thoracic aortas were investigated from which it is evident that the aortic media has much stronger resistance to rupture under 'out-of-plane' than under 'in-plane' shear loadings. Under different shear loadings the aortic tissues revealed anisotropic failure properties with higher ultimate shear stresses and amounts of shear in the longitudinal than in the circumferential direction. Furthermore, the aortic media decreased its tensile strength as follows: circumferential direction >longitudinaldirection> radial direction. Anisotropic and nonlinear tissue properties are apparent from the experimental data. The results clearly showed interspecimen differences influenced by the anamnesis of the donors such as aortic diseases or connective tissue disorders, e.g., dissected specimens exhibited on average a markedly lower mechanical strength than aneurysmatic specimens. The rupture data based on the combination of triaxial shear and uniaxial extension testing are unique and build a good basis for developing a 3D failure criterion of diseased human thoracic aortic media. This is a step forward to more realistic modeling of mechanically induced tissue failure i.e. rupture of aneurysms or progression of aortic dissections.

AB - Rupture of aneurysms and acute dissection of the thoracic aorta are life-threatening events which affect tens of thousands of people per year. The underlying mechanisms remain unclear and the aortic wall is known to lose its structural integrity, which in turn affects its mechanical response to the loading conditions. Hence, research on such aortic diseases is an important area in biomechanics. The present study investigates the mechanical properties of aneurysmatic and dissected human thoracic aortas via triaxial shear and uniaxial tensile testing with a focus on the former. In particular, ultimate stress values from triaxial shear tests in different orientations regarding the aorta׳s orthotropic microstructure, and from uniaxial tensile tests in radial, circumferential and longitudinal directions were determined. In total, 16 human thoracic aortas were investigated from which it is evident that the aortic media has much stronger resistance to rupture under 'out-of-plane' than under 'in-plane' shear loadings. Under different shear loadings the aortic tissues revealed anisotropic failure properties with higher ultimate shear stresses and amounts of shear in the longitudinal than in the circumferential direction. Furthermore, the aortic media decreased its tensile strength as follows: circumferential direction >longitudinaldirection> radial direction. Anisotropic and nonlinear tissue properties are apparent from the experimental data. The results clearly showed interspecimen differences influenced by the anamnesis of the donors such as aortic diseases or connective tissue disorders, e.g., dissected specimens exhibited on average a markedly lower mechanical strength than aneurysmatic specimens. The rupture data based on the combination of triaxial shear and uniaxial extension testing are unique and build a good basis for developing a 3D failure criterion of diseased human thoracic aortic media. This is a step forward to more realistic modeling of mechanically induced tissue failure i.e. rupture of aneurysms or progression of aortic dissections.

KW - Journal Article

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DO - 10.1016/j.jbiomech.2016.02.042

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JO - Journal of biomechanics

JF - Journal of biomechanics

SN - 0021-9290

IS - 12

ER -