Biaxial Mechanical Behavior of Aneurysmal and Nonaneurysmal Human Abdominal Aorta: Preliminary Results

2000 ◽  
Author(s):  
David A. Vorp ◽  
Michael S. Sacks ◽  
Brian J. Schiro ◽  
Michel S. Makaroun
Keyword(s):  
Stress Distribution ◽  
Mechanical Behavior ◽  
Abdominal Aorta ◽  
Large Strain ◽  
Constitutive Behavior ◽  
Accurate Estimation ◽  
Uniaxial Tensile ◽  
Aortic Tissue ◽  
Material Symmetry ◽  
Nonlinearly Elastic

Abstract Rupture of abdominal aortic aneurysm (AAA) is currently the 13th leading cause of death in the US and represents a mechanical failure of the diseased aortic wall. Therefore, accurate estimation of the wall stress distribution in AAA may be a clinically useful tool to predict their risk of rupture [1]. A necessary precursor to an accurate stress analysis is an appropriate representation of the constitutive behavior of the AAA wall. Many previous biomechanical analyses of AAA have employed a linearly elastic constitutive behavior [2,3]. However, we have shown that the AAA wall is nonlinearly elastic [4] and undergoes large strain in-vivo [5]. With this as motivation, we recently developed an isotropic, nonlinearly elastic, large strain constitutive model for AAA wall based on uniaxial tensile testing data [6]. The assumption of isotropy was not validated, however. Utilization of an isotropic material symmetry in models of anisotropic structures may lead to significant errors in stress distribution [7]. Indeed, experiments suggest that the nonaneurysmal aorta is anisotropic (orthotropic) [8,9], but the material symmetry of AAA is not presently known. Moreover, most of the previous work investigating the material symmetry of aorta has been performed on animal tissue. To evaluate the anisotropy of aortic tissue, biaxial experimentation is necessary. There has been very little published work involving the biaxial experimentation of human aortic tissue, and none for AAA tissue. We present here a preliminary evaluation of the biaxial mechanical behavior of human aneurysmal and nonaneurysmal abdominal aorta.

scholarly journals Effect of Decellularization Protocol on the Mechanical Behavior of Porcine Descending Aorta

2010 ◽  
Vol 2010 ◽  
pp. 1-11 ◽  
Author(s):  
John C. Fitzpatrick ◽  
Peter M. Clark ◽  
Franco M. Capaldi
Keyword(s):  
Mechanical Behavior ◽  
Vascular Tissue ◽  
Statistical Significance ◽  
Sodium Deoxycholate ◽  
Rnase A ◽  
Uniaxial Tensile ◽  
Aortic Tissue ◽  
Model Parameters ◽  
Test Analysis ◽  
Tissue Samples

Enzymatic-detergent decellularization treatments may use a combination of chemical reagents to reduce vascular tissue to sterilized scaffolds, which may be seeded with endothelial cells and implanted with a low risk of rejection. However, these chemicals may alter the mechanical properties of the native tissue and contribute to graft compliance mismatch. Uniaxial tensile data obtained from native and decellularized longitudinal aortic tissue samples was analyzed in terms of engineering stress and fit to a modified form of the Yeoh rubber model. One decellularization protocol used SDS, while the other two used TritonX-100, RNase-A, and DNase-I in combination with EDTA or sodium-deoxycholate. Statistical significance of Yeoh model parameters was determined by pairedt-test analysis. The TritonX-100/EDTA and 0.075% SDS treatments resulted in relatively variable mechanical changes and did not effectively lyse VSMCs in aortic tissue. The TritonX-100/sodium-deoxycholate treatment effectively lysed VSMCs and was characterized by less variability in mechanical behavior. The data suggests a TritonX-100/sodium-deoxycholate treatment is a more effective option than TritonX-100/EDTA and SDS treatments for the preparation of aortic xenografts and allografts because it effectively lyses VSMCs and is the least likely treatment, among those considered, to promote a decrease in mechanical compliance.

scholarly journals BIOMECHANICAL REMODELING OF BIODEGRADABLE SMALL-DIAMETER VASCULAR GRAFTS IN SITU

2016 ◽  
Vol 18 (2) ◽  
pp. 99-109 ◽  
Author(s):  
T. V. Glushkova ◽  
V. V. Sevostyanova ◽  
L. V. Antonova ◽  
K. Yu. Klyshnikov ◽  
E. A. Ovcharenko ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Blood Vessels ◽  
Abdominal Aorta ◽  
Internal Mammary Artery ◽  
Vascular Grafts ◽  
Small Diameter ◽  
Uniaxial Tensile ◽  
Aortic Tissue ◽  
Uniaxial Tensile Test ◽  
Internal Mammary

Aim: to evaluate the biomechanical remodeling of polymer grafts modified with vascular endothelial growth factor (VEGF) after implantation into rat abdominal aorta.Materials and methods. Vascular grafts of2 mmdiameter were fabricated by electrospinning from polycaprolactone (PCL) and a mixture of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) and PCL. The grafts were modified with VEGF by biphasic electrospinning. Morphology of the grafts was assessed by scanning electron microscopy. Physico-mechanical properties of PCL and PHBV/PCL grafts were estimated using uniaxial tensile test and physiological circulating system equipped with state-of-theart ultrasound vascular wall tracking system. Physico-mechanical testing of PCL/VEGF and PHBV/PCL/VEGF was performed before and after implantation into rat abdominal aorta for 6 months. The modeling of coronary artery bypass grafting (CABG) was performed by finite element analysis for modified grafts.Results. Durability of PCL and PHBV/PCL grafts did not differ from that of human internal mammary artery; however, elasticity and stiffness of these grafts were higher compared to internal mammary artery. Viscoelastic properties of the grafts were comparable to those of native blood vessels. Modification of the grafts with VEGF reduced material stiffness. Six months postimplantation, PCL/VEGF and PHBV/PCL/VEGF were integrated with aortic tissue that induced changes in the physico-mechanical properties of the grafts similar to the native vessel. Biomechanical modeling confirmed the functioning of modified grafts in bypass position for CABG.Conclusion. PCL/VEGF and PHBV/PCL/VEGF grafts have satisfactory physico-mechanical properties and can be potentially used in the reconstruction of blood vessels. 

On the Mechanical Behavior of Healthy and Aneurysmal Abdominal Aorta

2011 ◽  
Author(s):  
J. Ferruzzi ◽  
M. S. Enevoldsen ◽  
J. D. Humphrey
Keyword(s):  
Mechanical Behavior ◽  
Abdominal Aorta ◽  
Arterial Wall ◽  
Mechanical Response ◽  
Pathological Condition ◽  
Uniaxial Tensile ◽  
Infrarenal Aorta ◽  
Biaxial Testing ◽  
Biomechanical Behavior ◽  
Uniaxial Tensile Testing

Abdominal aortic aneurysm (AAA) is a pathological condition of the infrarenal aorta characterized by a local dilatation of the arterial wall. The main histopathologic features of an AAA are smooth muscle cell death and loss of elastin. The biomechanical behavior of AAAs has been widely studied to determine the rupture potential according to the principles of material failure. However, most prior approaches are limited by the use of data from uniaxial tensile testing and by the assumption of material isotropy, leading to inaccurate characterization of the 3D multiaxial mechanical response of the aneurysmal tissue. To date, the best data available on the behavior of human abdominal aorta (AA) and AAA to planar biaxial testing are the ones reported by Vande Geest et al. [1,2]. In a recent work [3], we considered a structurally motivated four-fiber family strain energy function (SEF) [4] to capture the biaxial behavior of the human AA and AAA from Vande Geest et al. [1,2]. We showed that this constitutive relation fits human data better than prior models and most importantly it captures the stiffening of the arterial wall related to both aging and aneurysmal development. These changes in mechanical behavior are mirrored by changes in the best-fit values of the parameters, with a progressive decrease of the isotropic part attributed to elastin and a parallel increase in values associated with the families of collagen fibers.

Influence of post-welding tempering on mechanical behavior of friction welded joints from medium-carbon steels during tensile test

2020 ◽  
pp. 40-49
Author(s):  
A. S. Atamashkin ◽  
E. Yu. Priymak ◽  
N. V. Firsova
Keyword(s):  
Mechanical Behavior ◽  
Welded Joints ◽  
Welded Joint ◽  
Crack Nucleation ◽  
Carbon Steels ◽  
Uniaxial Tensile ◽  
Medium Carbon ◽  
Uniaxial Tensile Testing ◽  
Rotary Friction Welding ◽  
Medium Carbon Steels

The paper presents an analysis of the mechanical behavior of friction samples of welded joints from steels 30G2 (36 Mn 5) and 40 KhN (40Ni Cr 6), made by rotary friction welding (RFW). The influence of various temperature conditions of postweld tempering on the mechanical properties and deformation behavior during uniaxial tensile testing is analyzed. Vulnerabilities where crack nucleation and propagation occurred in specimens with a welded joint were identified. It was found that with this combination of steels, postweld tempering of the welded joint contributes to a decrease in the integral strength characteristics under conditions of static tension along with a significant decrease in the relative longitudinal deformation of the tested samples.

scholarly journals Experimental and Numerical Evaluation of Mechanical Properties of 3D-Printed Stainless Steel 316L Lattice Structures

2021 ◽  
Author(s):  
M. Carraturo ◽  
G. Alaimo ◽  
S. Marconi ◽  
E. Negrello ◽  
E. Sgambitterra ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Mechanical Behavior ◽  
Numerical Simulations ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Lattice Structures ◽  
Stainless Steel 316L ◽  
Research Attention ◽  
Octet Truss

AbstractAdditive manufacturing (AM), and in particular selective laser melting (SLM) technology, allows to produce structural components made of lattice structures. These kinds of structures have received a lot of research attention over recent years due to their capacity to generate easy-to-manufacture and lightweight components with enhanced mechanical properties. Despite a large amount of work available in the literature, the prediction of the mechanical behavior of lattice structures is still an open issue for researchers. Numerical simulations can help to better understand the mechanical behavior of such a kind of structure without undergoing long and expensive experimental campaigns. In this work, we compare numerical and experimental results of a uniaxial tensile test for stainless steel 316L octet-truss lattice specimen. Numerical simulations are based on both the nominal as-designed geometry and the as-build geometry obtained through the analysis of µ-CT images. We find that the use of the as-build geometry is fundamental for an accurate prediction of the mechanical behavior of lattice structures.

Influence of the Welded Joint on the Mechanical Behavior of Steel Piles during Static and Dynamic Deformation

2007 ◽  
Vol 345-346 ◽  
pp. 1469-1472
Author(s):  
Gab Chul Jang ◽  
Kyong Ho Chang ◽  
Chin Hyung Lee
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Mechanical Behavior ◽  
Welded Joint ◽  
Dynamic Deformation ◽  
Three Dimensional ◽  
Steel Structures ◽  
Residual Stress Distribution ◽  
Dynamic Mechanical Behavior ◽  
Steel Piles

During manufacturing the welded joint of steel structures, residual stress is produced and weld metal is used inevitably. And residual stress and weld metal influence on the static and dynamic mechanical behavior of steel structures. Therefore, to predict the mechanical behavior of steel pile with a welded joint during static and dynamic deformation, the research on the influence of the welded joints on the static and dynamic behavior of steel pile is clarified. In this paper, the residual stress distribution in a welded joint of steel piles was investigated by using three-dimensional welding analysis. The static and dynamic mechanical behavior of steel piles with a welded joint is investigated by three-dimensional elastic-plastic finite element analysis using a proposed dynamic hysteresis model. Numerical analyses of the steel pile with a welded joint were compared to that without a welded joint with respect to load carrying capacity and residual stress distribution. The influence of the welded joint on the mechanical behavior of steel piles during static and dynamic deformation was clarified by comparing analytical results

Oxidative Activity of Aortic Tissue of Man, the Rabbit and the Dog, With Special Reference to Succinic Dehydrogenase and Cytochrome Oxidase

1958 ◽  
Vol 195 (2) ◽  
pp. 476-480 ◽  
Author(s):  
Nelicia Maier ◽  
Henry Haimovici
Keyword(s):  
Special Reference ◽  
Cytochrome Oxidase ◽  
Abdominal Aorta ◽  
Abdominal Segment ◽  
Species Difference ◽  
Succinic Dehydrogenase ◽  
Hepatic Tissue ◽  
Human Aorta ◽  
Aortic Tissue ◽  
Enzymatic Systems

Succinic dehydrogenase and cytochrome oxidase activities were determined in homogenates of three aortic segments (ascending and arch, descending thoracic, abdominal) and liver of man, the rabbit and the dog. Both enzymes exhibited the lowest activity in human aorta. Succinic dehydrogenase exhibited the highest activity in the thoracic aorta of the dog and intermediate activity in the latter's abdominal segment and the rabbit's aorta. Cytochrome oxidase, in contrast, exhibited the highest activity in the rabbit's aorta. A slight gradient of decreasing activity from thoracic to abdominal aorta was noted for cytochrome oxidase in both the rabbit and dog and for succinic dehydrogenase in the rabbit, whereas a significant decrease in the latter enzyme was noted in the abdominal segment of the dog. No gradient of activity was apparent in man. Liver exhibited the lowest activity for both enzymes in man, highest in the dog and intermediate in the rabbit. The above findings suggest a biologic species difference between the aorta of man, the rabbit and the dog, which may be partly ascribed to a difference in the components of the above two enzymatic systems. The same species difference holds true for hepatic tissue.

A Zebrafish Embryo Behaves both as a “Cortical Shell – Liquid Core” Structure and a Homogeneous Solid when Experiencing Mechanical Forces

2014 ◽  
Vol 20 (6) ◽  
pp. 1841-1847 ◽  
Author(s):  
Fei Liu ◽  
Dan Wu ◽  
Ken Chen
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Zebrafish Embryo ◽  
Large Strain ◽  
Liquid Core ◽  
Small Strain ◽  
Core Structure ◽  
Mechanical Forces ◽  
Cortical Shell ◽  
A Cell

AbstractMechanical properties are vital for living cells, and various models have been developed to study the mechanical behavior of cells. However, there is debate regarding whether a cell behaves more similarly to a “cortical shell – liquid core” structure (membrane-like) or a homogeneous solid (cytoskeleton-like) when experiencing stress by mechanical forces. Unlike most experimental methods, which concern the small-strain deformation of a cell, we focused on the mechanical behavior of a cell undergoing small to large strain by conducting microinjection experiments on zebrafish embryo cells. The power law with order of 1.5 between the injection force and the injection distance indicates that the cell behaves as a homogenous solid at small-strain deformation. The linear relation between the rupture force and the microinjector radius suggests that the embryo behaves as membrane-like when subjected to large-strain deformation. We also discuss the possible reasons causing the debate by analyzing the mechanical properties of F-actin filaments.

Mechanical behavior of chemically treated ostrich pericardium subjected to uniaxial tensile testing: influence of the suture

2002 ◽  
Vol 62 (1) ◽  
pp. 73-81 ◽  
Author(s):  
J. M. García Páez ◽  
A. Carrera ◽  
E. Jorge Herrero ◽  
I. Millán ◽  
A. Rocha ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Tensile Testing ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Testing ◽  
Chemically Treated

Spherical waves in a simple locking medium

1964 ◽  
Vol 54 (2) ◽  
pp. 737-754
Author(s):  
Sathyanarayana Hanagud
Keyword(s):  
Shock Wave ◽  
Stress Distribution ◽  
Mechanical Behavior ◽  
Spherical Cavity ◽  
Shear Resistance ◽  
Finite Deformations ◽  
Spherical Shock Wave ◽  
Spherical Waves ◽  
Spherical Shock ◽  
Elastic Shear

ABSTRACT The mechanical behavior of some types of soils can be idealized by that of a “Locking Solid.” This paper investigates the spherical shock wave and the stress distribution behind the wave in a simple locking solid due to a sudden explosion at the surface of a small spherical cavity. The cases of infinitesimal and finite deformations are considered. The effect of an elastic shear resistance and the consequent phenomenon of “unlocking” are also studied.

Sign in / Sign up

Export Citation Format

Share Document