Bulging bifurcation of inflated circular cylinders of doubly fiber-reinforced hyperelastic material under axial loading and swelling

2015 ◽  
Vol 22 (4) ◽  
pp. 666-682 ◽  
Author(s):  
Hasan Demirkoparan ◽  
Jose Merodio
Keyword(s):  
Potential Benefit ◽  
Arterial Wall ◽  
Axial Loading ◽  
Circular Cylinders ◽  
Orthotropic Materials ◽  
Aneurysm Formation ◽  
Inner Radius ◽  
Fiber Winding ◽  
Hoop Stresses ◽  
Winding Angle

In this paper, we examine the influence of swelling on the bulging bifurcation of inflated thin-walled cylinders under axial loading. We provide the bifurcation criteria for a membrane cylinder subjected to combined axial loading, internal pressure and swelling. We focus here on orthotropic materials with two preferred directions which are mechanically equivalent and are symmetrically disposed. Arterial wall tissue is modeled with this class of constitutive equation and the onset of bulging is considered to give aneurysm formation. It is shown that swelling may lead to compressive hoop stresses near the inner radius of the tube, which could have a potential benefit for preventing aneurysm formation. The effects of the axial stretch, the strength of the fiber reinforcement and the fiber winding angle on the onset of bifurcation are investigated. Finally, a boundary value problem is studied to show the robustness of the results.

On prismatic and bending bifurcations of fiber-reinforced elastic membranes under swelling with application to aortic aneurysms

2021 ◽  
pp. 108128652110587
Author(s):  
Murtadha J. Al-Chlaihawi ◽  
Heiko Topol ◽  
Hasan Demirkoparan ◽  
José Merodio
Keyword(s):  
Axial Loading ◽  
Material Constant ◽  
Exponential Model ◽  
Aortic Aneurysms ◽  
Orthotropic Materials ◽  
Fiber Direction ◽  
Fiber Reinforced ◽  
The Matrix ◽  
Elastic Membranes ◽  
Fiber Winding

The influence of swelling on prismatic and bending bifurcation modes of inflated thin-walled cylinders under axial loading is examined. The bifurcation criteria for a membrane cylinder subjected to combined axial loading, internal pressure, and swelling is provided. We consider orthotropic materials with two preferred directions which are mechanically equivalent and symmetrically disposed. The mechanical behavior of the matrix is described by a swellable isotropic model. The isotropic material is augmented with two functions that are equal, each one of them accounting for the existence of a unidirectional reinforcement. Two reinforcing models that depend only on the stretch in the fiber direction are considered: the so-called standard reinforcing model and an exponential one. The analysis of bifurcation modes for these models under the conditions at hand may establish the connection with modeling of the normal and diseased aorta in arterial wall tissue. The effects of the axial stretch, the strength of the fiber reinforcement and the fiber winding angle on the onset of prismatic and bending bifurcations are investigated. It is shown that for membranes without fibers, prismatic bifurcation is not feasible. On the other hand, bending bifurcation is more likely to occur for swollen cylinders. However, for a particular model of fiber-reinforced membranes, the standard model, there exists a domain of deformation values together with material constant values that may trigger prismatic bifurcation. The exponential model does not allow prismatic bifurcations. Both models allow bending bifurcation and may or may not trigger it depending on the deformation together with material parameters.

Histologically verified cerebral aneurysm formation secondary to embolism from cardiac myxoma

1995 ◽  
Vol 83 (1) ◽  
pp. 170-173 ◽  
Author(s):  
Kazuhide Furuya ◽  
Tomio Sasaki ◽  
Yuhei Yoshimoto ◽  
Yoshifumi Okada ◽  
Takamitsu Fujimaki ◽  
...  
Keyword(s):  
Tumor Cells ◽  
Cardiac Tumor ◽  
Arterial Wall ◽  
Cardiac Myxoma ◽  
Cerebral Aneurysms ◽  
Surgical Removal ◽  
Arterial Aneurysm ◽  
Content Type ◽  
Aneurysm Formation ◽  
Aneurysm Wall

✓ Multiple aneurysm formation secondary to an embolism from the cardiac myxoma is a well-known phenomenon. The cerebral arterial aneurysm formation process involved remains to be elucidated, although occupation of the arterial wall by tumor cells has been proven histologically. The authors present the case of a patient in whom tumor cells in the aneurysm wall were demonstrated and penetration of viable myxoma cells into the wall was also observed 19 months after surgical removal of the cardiac tumor. Such findings have never before been verified histologically. In light of the histological findings, the authors discuss the therapeutic problems associated with cerebral aneurysms resulting from cardiac myxoma.

Dynamics of Arterial Remodeling in Response to a Sustained Step Change in Blood Flow Using a Constituent-Based Model

2007 ◽  
Author(s):  
Alkiviadis Tsamis ◽  
Nikos Stergiopulos
Keyword(s):  
Blood Flow ◽  
Arterial Wall ◽  
Wall Stress ◽  
Step Change ◽  
Local Blood Flow ◽  
Inner Radius ◽  
Flow Changes ◽  
Baseline Levels ◽  
Two Phases

The arterial wall undergoes substantial remodeling whenever the local blood flow changes for more than a few days [1]. An increase in flow causes an increase in inner radius, which occurs in two phases and tends to restore the baseline levels of intimal shear stress [2]. Firstly, an acute dilation of the artery occurs due to relaxation of vascular smooth muscle (VSM) cells [3]. Secondly, a long-term media reconstruction takes place, during which VSM cells migrate and proliferate circumferentially causing an increase in undeformed lumen. Moreover, arterial wall thickens to restore the altered wall stress [4].

Swelling and axial propagation of bulging with application to aneurysm propagation in arteries

2017 ◽  
Vol 25 (7) ◽  
pp. 1459-1471 ◽  
Author(s):  
Hasan Demirkoparan ◽  
Jose Merodio
Keyword(s):  
Arterial Wall ◽  
Mechanical Response ◽  
Axial Loading ◽  
Fiber Direction ◽  
Wall Model ◽  
Analytical Methodology ◽  
Unidirectional Reinforcement ◽  
Anisotropic Character ◽  
Parameter Values ◽  
Linearly Elastic Materials

The effect of swelling on axial propagation of bulging is investigated for thin cylinders made of doubly fiber reinforced incompressible non-linearly elastic materials. The swellable tubes are exposed to both internal pressure and axial loading. The materials under consideration are Treloar models augmented with two functions that are equal, each one of them accounting for the existence of a unidirectional reinforcement. The functions provide the anisotropic character of the material and each one is referred to as a reinforcing model. Two reinforcing models that depend only on the stretch in the fiber direction are considered: the so called standard reinforcing model and an exponential one. The former model is studied to assess the analytical methodology described in this paper. The latter one is related to soft tissue mechanical response and bulging propagation in these models establishes the connection with the propagation of aneurysms in arterial wall tissue. For the standard reinforcing model, it is shown that axial propagation of bulging is not feasible. On the other hand, for the arterial wall model axial propagation of bulging is possible for a certain range of material parameter values.

The Investigation of Prestressed Pressure Pipes, Reinforced with Fiberglass Plastic

2018 ◽  
Vol 36 ◽  
pp. 1-11
Author(s):  
L.V. Trykoz ◽  
S.M. Kamchatnaya ◽  
O.M. Pustovoitova ◽  
A.O. Atynian
Keyword(s):  
Reinforced Concrete ◽  
Concrete Core ◽  
Concrete Pipe ◽  
Force Transfer ◽  
Combined Action ◽  
Stress And Deformation ◽  
Hoop Stresses ◽  
The Given ◽  
Winding Angle

The problem of a combined action of reinforced concrete pipe and fiberglass safety cage. The prestressed cage not only decreases deformability of a pipe under load but protects the material of a pipe from agressive external factors. The process of force transfer from concrete pipe and fiberglass has been analyzed and the equation of stress and deformation for pipes and fiberglass has been deduced. It is shown that stress in fiberglass does not remain constant varying wall thickness, reducing towards the concrete core. Hoop stresses in the concrete core increase towards the centre of a pipe. Unlike known solutions the performed calculations take into account the performance of both layers – concrete and fiberglass. The total stresses in a concrete pipe in the most dangerous section from internal pressure and the reduction by fiberglass winding have been determined. The results obtained in the given work provide with the possibility of modelling long-term properties of composite reinforced concrete constructions and optimization of winding angle of fiberglass casing depending on the diameter of a pipe, tension force and the quantity of reinforcing filler.

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