scholarly journals Effect of Axial Stretch on Lumen Collapse of Arteries

2016 ◽  
Vol 138 (12) ◽  
Author(s):  
Fatemeh Fatemifar ◽  
Hai-Chao Han
Keyword(s):  
Critical Value ◽  
Stretch Ratio ◽  
External Pressure ◽  
Element Analysis ◽  
Axial Stretch ◽  
Axial Tension ◽  
The Stability ◽  
Collapse Behavior ◽  
Critical Buckling Pressure

The stability of the arteries under in vivo pressure and axial tension loads is essential to normal arterial function, and lumen collapse due to buckling can hinder the blood flow. The objective of this study was to develop the lumen buckling equation for nonlinear anisotropic thick-walled arteries to determine the effect of axial tension. The theoretical equation was developed using exponential Fung strain function, and the effects of axial tension and residual stress on the critical buckling pressure were illustrated for porcine coronary arteries. The buckling behavior was also simulated using finite-element analysis. Our results demonstrated that lumen collapse of arteries could occur when the transmural pressure is negative and exceeded a critical value. This value depends upon the axial stretch ratio and material properties of the arterial wall. Axial tensions show a biphasic effect on the critical buckling pressure. The lumen aspect ratio of arteries increases nonlinearly with increasing external pressure beyond the critical value as the lumen collapses. These results enhance our understanding of artery lumen collapse behavior.

The Stability of Veins Under Torsion

2012 ◽  
Author(s):  
Justin R. Garcia ◽  
Hai-Chao Han
Keyword(s):  
Diabetes Mellitus ◽  
Health Risks ◽  
Mechanical Stability ◽  
Thrombus Formation ◽  
Body Movement ◽  
Critical Value ◽  
The Body ◽  
Clinical Interest ◽  
The Stability

Twisted veins are observed throughout the body and are often associated with health risks such as hypertension and diabetes mellitus [1]. Recently, it has been shown that veins will buckle and become tortuous when lumen pressure exceeds a critical value [2]. However, veins also undergo twist deformations in vivo due to body movement, vein grafting, and microanastomosis procedures which may lead to reduced patency, kinking, and thrombus formation [3, 4]. In spite of this, little data is available regarding the stability of veins when subject to twist deformations. Therefore, it is of clinical interest to investigate the mechanical stability of veins under torsion.

Finite Element Analysis for the Stiffness and the Buckling of Corrugated Tubes in Heat Exchanger

2012 ◽  
Vol 468-471 ◽  
pp. 1675-1680 ◽  
Author(s):  
Xiao Jing Wang ◽  
Zhi Min Wang ◽  
Nian Wang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stability Analysis ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
External Pressure ◽  
Element Analysis ◽  
Value Analysis ◽  
Compressive Pressure ◽  
The Stability

Corrugated tubes in a heat exchanger are analyzed by using the FEA methods. And the formula how to compute single wave’s rigidity is obtained. Besides, methods of analyzing the stability of corrugated tubes under internal compressive pressure and external pressure are proposed which include characteristic value analysis and non-linear stability analysis, thus providing theory basis for the stability research of heat exchangers.

A Basic Theory of Artery Buckling Under Internal Pressure

2009 ◽  
Author(s):  
Hai Chao Han
Keyword(s):  
Internal Pressure ◽  
Stretch Ratio ◽  
External Pressure ◽  
Mode Shapes ◽  
Theoretical Base ◽  
Linear And Nonlinear ◽  
Elastic Artery ◽  
The Stability ◽  
Nonlinear Elastic ◽  
Arteries And Veins

The stability of blood vessels under the lumen blood pressure load is essential to the maintenance of normal arterial function. It has been well documented that arteries and veins collapse when the internal lumen pressure is too low and/or the external pressure become higher than the internal pressure [1–3]. It has been demonstrated recently that arteries and veins also buckle (bend) due to hypertensive pressure or a reduced axial stretch ratio [4]. Buckling equations have been established recently for linear and nonlinear elastic artery and vein models based on assumed sinusoidal mode shapes [4–6]. However, the theoretical base for the assumption is lacking. It is necessary to determine whether arteries can bifurcate into the buckled shape under internal pressure.

Buckling Behavior of General Dome Ends under External Pressure, Using Finite Element Analysis

2011 ◽  
Vol 471-472 ◽  
pp. 833-838 ◽  
Author(s):  
Behzad Abdi ◽  
Hamid Mozafari ◽  
Ayob Amran
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Major Axis ◽  
External Pressure ◽  
Geometrical Parameters ◽  
Element Analysis ◽  
Buckling Behavior ◽  
Ellipse Method ◽  
The Finite Element Analysis ◽  
Critical Buckling Pressure

In this paper, the finite element analysis is used to investigate the effect of shape of dome ends on the buckling of pressure vessel heads under external pressure. The Finite Element Analysis (FEA) with the use of elastic buckling analysis was applied to predict the critical buckling pressure. The influence of geometrical parameters such as thickness, knuckle radius, and the ratio of minor axis to the major axis of dome ends, on the weight and the critical buckling pressure of hemispherical, ellipsoidal, and torispherical dome ends, was studied. The four-centered ellipse method was used to describe the geometry of the dome end.

Cost-Effective Method of Optimization of Stacking Sequences in the Cylindrical Composite Shells Using Genetic Algorithm

2020 ◽  
Author(s):  
Ehsan Daneshkhah ◽  
Reza Jafari Nedoushan ◽  
Davoud Shahgholian ◽  
Nima Sina
Keyword(s):  
Genetic Algorithm ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Experimental Tests ◽  
Cost Effective ◽  
Element Model ◽  
External Pressure ◽  
Element Analysis ◽  
Cost Effective Method ◽  
Critical Buckling Pressure

Buckling is one of the common destructive phenomena, which occurs in composite cylinders subjected to external pressure. In this paper, different methods to optimize stacking sequence of these cylinders are investigated. A finite element model is proposed in order to predict critical buckling pressure and the results are validated with previous experimental data. Theoretical analysis based on NASA SP‐8007 solution and the simplified equation for cylinder buckling of ASME RD-1172 are presented and discussed. The results of theoretical and finite element analysis and experimental tests are compared for both glass and carbon epoxy cylinders. Using NASA and ASME formulations, optimal laminations of cylinders in order to maximize buckling pressure, are obtained by genetic algorithm method. Suggested laminations and the values of corresponding critical buckling pressure calculated by finite element analysis, are presented and compared in various states. Obtained results show that while predicted buckling loads of finite element analysis are reliable, NASA formulation can be used in a very cost-effective method to optimize the buckling problems.

Thermal Effect on Buckling of General Dome Ends Using Finite Element Method

2011 ◽  
Vol 121-126 ◽  
pp. 340-345
Author(s):  
Behzad Abdi ◽  
Hamid Mozafari ◽  
Ayob Amran ◽  
Roya Kohandel
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Major Axis ◽  
External Pressure ◽  
Effect Of Temperature ◽  
Elastic Buckling ◽  
Geometrical Parameters ◽  
Element Analysis ◽  
Critical Buckling Pressure ◽  
Element Method

In this study, the elastic buckling behavior of general dome ends under presumed temperature distribution and external pressure was studied. The Finite Element Method (FEM) was used to predict the elastic buckling pressure behavior when the domes were subjected to various operating temperatures. The freedom of the edges of the dome ends was completely restricted to simulate clamped end conditions. The four-centered ellipse method was used to construct the geometry of the dome ends. The influence of geometrical parameters such as thickness, knuckle radius, and the ratio of minor axis to the major axis of dome ends and the effect of temperature on critical buckling pressure of hemispherical, ellipsoidal, and torispherical dome ends were studied. It has been found that the under thermal condition, the thickness and the shape of the domes have the most significant effect on the critical buckling pressure. Two models of torispherical and ellipsoidal dome ends are analyzed by using finite element analysis.

A STRUCTURE-MOTIVATED MODEL OF THE PASSIVE MECHANICAL RESPONSE OF THE PRIMARY PORCINE RENAL ARTERY

2014 ◽  
Vol 14 (03) ◽  
pp. 1450033 ◽  
Author(s):  
BORAN ZHOU ◽  
LAUREN WOLF ◽  
ALEXANDER RACHEV ◽  
TAREK SHAZLY
Keyword(s):  
Renal Artery ◽  
Arterial Wall ◽  
Mechanical Response ◽  
Physiological Function ◽  
Functional Dependence ◽  
Stretch Ratio ◽  
Comprehensive Description ◽  
Axial Stretch ◽  
Theoretical Predictions

The primary renal arteries transport up to one fourth of cardiac output to the kidneys for blood plasma ultrafiltration, with a functional dependence on the vessel geometry, composition and mechanical properties. Despite the critical physiological function of the renal artery, the few biomechanical studies that have focused on this vessel are either uniaxial or only partially describe its bi-axial mechanical behavior. In this study, we quantify the passive mechanical response of the primary porcine renal artery through bi-axial mechanical testing that probes the pressure-deformed diameter and pressure-axial force relationships at various longitudinal extensions, including the in-vivo axial stretch ratio. Mechanical data are used to parameterize and validate a structure-motivated constitutive model of the arterial wall. Together, experimental data and theoretical predictions of the stress distribution within the arterial wall provide a comprehensive description of the passive mechanical response of the porcine renal artery.

Role of bronchial basement membrane in airway collapse

1991 ◽  
Vol 71 (2) ◽  
pp. 666-673 ◽  
Author(s):  
R. K. Lambert
Keyword(s):  
Basement Membrane ◽  
Bronchial Hyperresponsiveness ◽  
External Pressure ◽  
Elastic Tube ◽  
Mechanical Stiffness ◽  
Airway Collapse ◽  
Collapse Behavior ◽  
Critical Buckling Pressure ◽  
Uniform Liquid

Bronchial basement membrane is an elastic structure that has the potential to be load bearing and thus to contribute to the mechanical stiffness of the bronchus. To investigate this possible role, the membrane was modeled as a thin-walled linearly elastic tube surrounded by a uniform liquid on the outside and by air on the inside. When the external pressure on such a tube exceeds the internal pressure by a critical amount, the tube buckles reversibly into two or more folds. The critical buckling pressure varies as the square of the number of folds. The analysis was used to investigate the collapse behavior of the model tube into patterns ranging from 2 to 24 folds. This showed that the resistance to collapse increases rapidly as the number of folds increases. Data in the literature lead to the conclusion that the pressures involved in collapsing the tubes are probably in the physiological range. It is suggested, on the basis of the model results reported here, that bronchial hyperresponsiveness could be related to the number of folds into which the basement membrane buckles when the bronchial muscle contracts. A reduced number of folds would yield an increased response.

Nonlinear Finite Element Analysis of Pressurized Spherical Shell for Deep Water Structure

2007 ◽  
Author(s):  
Liangbi Li ◽  
Renhua Wang ◽  
Minghua Yu ◽  
Zili Wang
Keyword(s):  
Finite Element ◽  
Spherical Shell ◽  
Deep Water ◽  
Water Structure ◽  
Nonlinear Finite Element ◽  
Yield Strain ◽  
Element Analysis ◽  
The Stability ◽  
Material Nonlinear ◽  
Critical Buckling Pressure

One of the main problems in developing the deep water structure is the stability of the pressurized spherical shell. If the pressurized spherical shell belongs to moderate thick shell, the transverse shear deformation must be taken into account. Based on the nonlinear finite element method, the stability of the pressurized spherical shell under deep water was studied in this paper. The influence of out of roundness due to the machining, the interaction between material nonlinear and geometry nonlinear were considered. They are caused by material yield, strain intensifying and big plastic deformation of the whole shell structure buckling. Results from calculation showed that the critical buckling pressure decreases with the increasing of the radius under the same thickness but increases with the thickness under the same radius. The relationship charts of the critical buckling pressure, the thickness, the radius of the pressurized spherical shell were derived. The reasonable geometric parameters were then selected.

scholarly journals A Novel Approach to Assess the In Situ Versus Ex Vivo Mechanical Behaviors of the Coronary Artery

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Ruoya Wang ◽  
Julia Raykin ◽  
Luke P. Brewster ◽  
Rudolph L. Gleason
Keyword(s):  
Mechanical Behavior ◽  
Ex Vivo ◽  
Stretch Ratio ◽  
Biaxial Testing ◽  
Axial Stretch ◽  
Arterial Mechanics ◽  
Novel Approach ◽  
The Impact

Ex vivo mechanical testing has provided tremendous insight toward prediction of the in vivo mechanical behavior and local mechanical environment of the arterial wall; however, the role of perivascular support on the local mechanical behavior of arteries is not well understood. Here, we present a novel approach for quantifying the impact of the perivascular support on arterial mechanics using intravascular ultrasound (IVUS) on cadaveric porcine hearts. We performed pressure-diameter tests (n = 5) on the left anterior descending coronary arteries (LADCAs) in situ while embedded in their native perivascular environment using IVUS imaging and after removal of the perivascular support of the artery. We then performed standard cylindrical biaxial testing on these vessels ex vivo and compared the results. Removal of the perivascular support resulted in an upward shift of the pressure-diameter curve. Ex vivo testing, however, showed significantly lower circumferential compliance compared to the in situ configuration. On a second set of arteries, local axial stretch ratios were quantified (n = 5) along the length of the arteries. The average in situ axial stretch ratio was 1.28 ± 0.16; however, local axial stretch ratios showed significant variability, ranging from 1.01 to 1.70. Taken together, the data suggest that both the perivascular loading and the axial tethering have an important role in arterial mechanics. Combining nondestructive testing using IVUS with traditional ex vivo cylindrical biaxial testing yields a more comprehensive assessment of the mechanical behavior of arteries.

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