Stress Distribution in a Bilayer Elastic Model of a Coronary Artery

2013 ◽  
Vol 80 (4) ◽  
Author(s):  
Keiichi Takamizawa ◽  
Yasuhide Nakayama
Keyword(s):  
Blood Pressure ◽  
Residual Stress ◽  
Stress Distribution ◽  
Residual Strain ◽  
Arterial Wall ◽  
Circumferential Stress ◽  
Outer Region ◽  
Constitutive Law ◽  
Elastic Model ◽  
The Media

In earlier studies on stress distribution in arteries, a monolayer wall model was often used. An arterial wall consists of three layers, the intima, the media, and the adventitia. The intima is mechanically negligible as a stress supporting layer against the blood pressure in young healthy vessels, although it is important as an interface between blood and arterial wall. The media and adventitia layers are considered to support blood pressure. Recently, residual strain and a constitutive law for porcine coronary arteries have been investigated in separated media and adventitia. Using the data obtained through these investigations, a stress analysis considering residual stress (strain) in each layer was performed in this study, and residual strain and stress were computed for a bilayer model. The circumferential residual stress was compressive in the inner region, tensile in the outer region, and had discontinuity at the boundary between the media and adventitia. A peak circumferential stress occurred in the media at the boundary between the media and adventitia under a physiological condition, and an almost flat distribution was obtained in the adventitia. This pattern does not change under a hypertensive condition. These results suggest that a remodeling with hypertension occurs in the media.

Effect of Residual Stress and Heterogeneity on Circumferential Stress in the Arterial Wall

2000 ◽  
Vol 122 (4) ◽  
pp. 454-456 ◽  
Author(s):  
S. J. Peterson ◽  
R. J. Okamoto
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Material Properties ◽  
Arterial Wall ◽  
Circumferential Stress ◽  
Single Species ◽  
Opening Angle ◽  
Layer Model ◽  
Multiple Sources ◽  
The Media

Quantifying the stress distribution through the arterial wall is essential to studies of arterial growth and disease. Previous studies have shown that both residual stress, as measured by opening angle, and differing material properties for the media-intima and the adventitial layers affect the transmural circumferential stress σθ distribution. Because a lack of comprehensive data on a single species and artery has led to combinations from multiple sources, this study determined the sensitivity of σθ to published variations in both opening angle and layer thickness data. We fit material properties to previously published experimental data for pressure–diameter relations and opening angles of rabbit carotid artery, and predicted σθ through the arterial wall at physiologic conditions. Using a one-layer model, the ratio of σθ at the internal wall to the mean σθ decreased from 2.34 to 0.98 as the opening angle increased from 60 to 130 deg. In a two-layer model using a 95 deg opening angle, mean σθ in the adventitia increased (112 percent for 25 percent adventitia) and mean σθ in the media decreased (47 percent for 25 percent adventitia). These results suggest that both residual stress and wall layers have important effects on transmural stress distribution. Thus, experimental measurements of loading curves, opening angles, and wall composition from the same species and artery are needed to accurately predict the transmural stress distribution in the arterial wall. [S0148-0731(00)02204-4]

Residual Stress and Circumferential Stress Distribution in a Finite Element Model of the Arterial Wall

Volume 2 ◽  
2004 ◽  
Author(s):  
Nooshin Haghighipour ◽  
Mohammad Tafazzoli Shadpour ◽  
Albert Avolio
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Distribution ◽  
Tensile Stress ◽  
Arterial Wall ◽  
Stress Component ◽  
Circumferential Stress ◽  
Opening Angle ◽  
Human Aorta ◽  
Endothelial Lining

Stress distribution of the arterial wall is an important factor in biomechanics of arteries. It has been suggested that excessive stress leads to arterial degeneration and lesion formation. In addition to circumferential tensile stress caused by luminal pressure, arterial wall contains circumferential residual stress with compressive and tensile components with maximum values on intima and adventitia respectively. The compressive residual stress component compensates part of maximum tensile stress, and therefore decreases severity of tension on endothelial lining. If an arterial ring is cut in radial direction it opens. The degree of opening angle is a determinant of circumferential residual stress. In this investigation, Finite element modeling was used to evaluate circumferential residual stress in a typical model of cross section of human aorta with differing opening angle and Young’s modulus of elasticity. Results show that residual stress values are influenced by structural and mechanical parameters. Elevation of the opening angle and stiffening of the arterial wall resulted in increase of residual stress level.

Non-Euclidean Stress-Free Configuration of Arteries Accounting for Curl of Axial Strips Sectioned From Vessels

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Keiichi Takamizawa ◽  
Yasuhide Nakayama
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Stress Analysis ◽  
Riemannian Geometry ◽  
Axial Stress ◽  
Circumferential Stress ◽  
Arterial Walls ◽  
Physiological Loading ◽  
Residual Strains

It is well known that arteries are subject to residual stress. In earlier studies, the residual stress in the arterial ring relieved by a radial cut was considered in stress analysis. However, it has been found that axial strips sectioned from arteries also curled into arcs, showing that the axial residual stresses were relieved from the arterial walls. The combined relief of circumferential and axial residual stresses must be considered to accurately analyze stress and strain distributions under physiological loading conditions. In the present study, a mathematical model of a stress-free configuration of artery was proposed using Riemannian geometry. Stress analysis for arterial walls under unloaded and physiologically loaded conditions was performed using exponential strain energy functions for porcine and human common carotid arteries. In the porcine artery, the circumferential stress distribution under physiological loading became uniform compared with that without axial residual strain, whereas a gradient of axial stress distribution increased through the wall thickness. This behavior showed almost the same pattern that was observed in a recent study in which approximate analysis accounting for circumferential and axial residual strains was performed, whereas the circumferential and axial stresses increased from the inner surface to the outer surface under a physiological condition in the human common carotid artery of a two-layer model based on data of other recent studies. In both analyses, Riemannian geometry was appropriate to define the stress-free configurations of the arterial walls with both circumferential and axial residual strains.

scholarly journals Intimal and medial contributions to the hydraulic resistance of the arterial wall at different pressures: a combined computational and experimental study

2016 ◽  
Vol 13 (119) ◽  
pp. 20160234 ◽  
Author(s):  
K. Y. Chooi ◽  
A. Comerford ◽  
S. J. Sherwin ◽  
P. D. Weinberg
Keyword(s):  
Hydraulic Resistance ◽  
Arterial Wall ◽  
Ex Vivo ◽  
Water Flux ◽  
Applied Pressure ◽  
Volumetric Strain ◽  
Transport Processes ◽  
Constitutive Law ◽  
Hydraulic Permeability ◽  
The Media

The hydraulic resistances of the intima and media determine water flux and the advection of macromolecules into and across the arterial wall. Despite several experimental and computational studies, these transport processes and their dependence on transmural pressure remain incompletely understood. Here, we use a combination of experimental and computational methods to ascertain how the hydraulic permeability of the rat abdominal aorta depends on these two layers and how it is affected by structural rearrangement of the media under pressure. Ex vivo experiments determined the conductance of the whole wall, the thickness of the media and the geometry of medial smooth muscle cells (SMCs) and extracellular matrix (ECM). Numerical methods were used to compute water flux through the media. Intimal values were obtained by subtraction. A mechanism was identified that modulates pressure-induced changes in medial transport properties: compaction of the ECM leading to spatial reorganization of SMCs. This is summarized in an empirical constitutive law for permeability and volumetric strain. It led to the physiologically interesting observation that, as a consequence of the changes in medial microstructure, the relative contributions of the intima and media to the hydraulic resistance of the wall depend on the applied pressure; medial resistance dominated at pressures above approximately 93 mmHg in this vessel.

Circumferential Residual Stress Distribution and Its Influence in a Diseased Carotid Artery

2009 ◽  
Author(s):  
Massimo Pocaterra ◽  
Hao Gao ◽  
Saroj Das ◽  
Michele Pinelli ◽  
Quan Long
Keyword(s):  
Residual Stress ◽  
Carotid Artery ◽  
Stress Distribution ◽  
Material Properties ◽  
Arterial Wall ◽  
Biological Tissues ◽  
Residual Stress Distribution ◽  
Normal Blood Pressure ◽  
Pressure Loading ◽  
Linear Material

Residual stresses are present in a variety of biological tissues, such as the arteries [1]. It is believed that residual stress tends to make stress distribution more uniform throughout normal arterial wall [2]. However, the influence of residual stress in a diseased artery remains unclear. The aim of this study is to investigate the circumferential residual stress in a diseased carotid artery (atherosclerotic plaque) and its influence on the stress distribution under normal blood pressure loading. To achieve a more realistic stress analysis, an anisotropic non-linear material properties based on ANSYS™ framework with parameter constants, obtained according to Gasser et al [3], was used for all simulations in the study.

Neutron Diffraction Studies of Residual Stress Distribution in the Vicinity of the Single Pass Fillet Steel Welds

2015 ◽  
Vol 732 ◽  
pp. 13-19
Author(s):  
Ľuboš Mráz ◽  
Leif Karlsson ◽  
Miroslav Vrána ◽  
Pavol Mikula
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Neutron Diffraction ◽  
Residual Strain ◽  
Residual Stress Distribution ◽  
Filler Materials ◽  
Single Pass ◽  
Stress Measurements ◽  
Strain Stress ◽  
Steel Welds

In this contribution the results of residual strain/stress measurements performed on several single pass fillet steel welds which were carried out at different welding conditions, namely, with different filler materials are presented.

Residual stress distribution in a lamellar model of the arterial wall

2010 ◽  
Vol 34 (7-8) ◽  
pp. 422-428 ◽  
Author(s):  
Nooshin Haghighipour ◽  
Mohammad Tafazzoli-Shadpour ◽  
Albert Avolio
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Arterial Wall ◽  
Residual Stress Distribution

scholarly journals Modelling the layer-specific three-dimensional residual stresses in arteries, with an application to the human aorta

2009 ◽  
Vol 7 (46) ◽  
pp. 787-799 ◽  
Author(s):  
Gerhard A. Holzapfel ◽  
Ray W. Ogden
Keyword(s):  
Residual Stress ◽  
Circumferential Stress ◽  
Three Dimensional ◽  
Residual Deformation ◽  
Cylindrical Tube ◽  
Opening Angle ◽  
Human Aorta ◽  
Geometrical Parameters ◽  
Artery Wall ◽  
The Media

This paper provides the first analysis of the three-dimensional state of residual stress and stretch in an artery wall consisting of three layers (intima, media and adventitia), modelled as a circular cylindrical tube. The analysis is based on experimental results on human aortas with non-atherosclerotic intimal thickening documented in a recent paper by Holzapfel et al. ( Holzapfel et al. 2007 Ann. Biomed. Eng. 35 , 530–545 ( doi:10.1007/s10439-006-9252-z )). The intima is included in the analysis because it has significant thickness and load-bearing capacity, unlike in a young, healthy human aorta. The mathematical model takes account of bending and stretching in both the circumferential and axial directions in each layer of the wall. Previous analysis of residual stress was essentially based on a simple application of the opening-angle method, which cannot accommodate the three-dimensional residual stretch and stress states observed in experiments. The geometry and nonlinear kinematics of the intima, media and adventitia are derived and the associated stress components determined explicitly using the nonlinear theory of elasticity. The theoretical results are then combined with the mean numerical values of the geometrical parameters and material constants from the experiments to illustrate the three-dimensional distributions of the stretches and stresses throughout the wall. The results highlight the compressive nature of the circumferential stress in the intima, which may be associated with buckling of the intima and its delamination from the media, and show that the qualitative features of the stretch and stress distributions in the media and adventitia are unaffected by the presence or absence of the intima. The circumferential residual stress in the intima increases significantly as the associated residual deformation in the intima increases while the corresponding stress in the media (which is compressive at its inner boundary and tensile at its outer boundary) is only slightly affected. The theoretical framework developed herein enables the state of residual stress to be calculated directly, serves to improve insight into the mechanical response of an unloaded artery wall and can be extended to accommodate more general geometries, kinematics and states of residual stress as well as more general constitutive models.

Comparison of Neutron and Synchrotron Diffraction Measurements of Residual Stress in Bead-on-Plate Weldments

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
Anna M. Paradowska ◽  
John W. H. Price ◽  
Trevor R. Finlayson ◽  
Ulrich Lienert ◽  
Raafat Ibrahim
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Residual Strain ◽  
Development Process ◽  
Synchrotron Diffraction ◽  
Stress Relieving ◽  
Before And After ◽  
Strain Stress ◽  
Good Agreement

This paper explores the use of neutron and synchrotron diffractions for the evaluation of residual stresses in welded components. It has been shown that it is possible to achieve very good agreement between the two independent diffraction techniques. This study shows the significance of the weld start and end sites on the residual strain/stress distribution. Quantitative evaluation of the residual stress development process for multibead weldments has been presented. Some measurements were also taken before and after postweld stress relieving to establish the reduction and redistribution of the residual stress. The detailed measurements of residual stress around the weld achieved in this work significantly improve the knowledge and understanding of residual stress in welded components.

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