In this study, a surrogate lung material, developed to mimic the lungs behaviour in low and high rate impact tests in order to better understand the damage mechanism in the lungs resulting from car crashes, collisions and explosion [1], is tested and characterised. This aims to eliminate the practice of live animal testing. The surrogate lung consists of polyurethane foam mixed with gelatine microcapsules filled with Barium Sulphate solution. Thus, both the foam and microcapsules must be individually characterised in addition to the surrogate lung itself when treated as a continuum material. For this, a number of compression tests were carried out on each material to ascertain their mechanical properties. On the other hand, the damage to the surrogate lung specimens as represented by burst microcapsules was analysed by carrying out CT scans before and after testing. The results show that the modulus of elasticity increases with the test speed. CT scan results clearly demonstrated the magnitude and distribution of damage within the specimen.

Numerical studies are widely employed in establishing blood flow transients in arteries. Unfortunately, many of these are based on rigid arterial geometries where the physiological interaction between the flowing blood and the dynamics of a deforming arterial wall is ignored. Although many recent studies have adopted a fluid-structure interaction (FSI) approach, they lack the necessary validation and, thus, cannot guarantee the accuracy of their predictions. This work employs a well-validated FSI model to establish the dependency of WSS transients on arterial flexibility and predict flow transients in arterial geometries. Results show a high dependency of WSS transients on arterial wall flexibility, with hoop strains of as low as 0.15% showing significant differences in these transients compared to that seen in a rigid geometry. It is also shown that flow in the atherosclerosis susceptible regions of the vascular tree is characterised by a highly disturbed flow. In these regions, WSS magnitudes are at their lowest, while the WSS spatial gradients, rate of change and oscillatory shear index are at their highest.

This paper deals with the determination of stress concentration factors using numerical methods. The cases of the bar with circular cross section and U-shaped groove subjected to tension and bending are considered. Determination of model parameters is achieved by combining the design-of-experiment, implemented in MATLAB, and Finite Element analysis, as an alternative to standard mechanical tests. The design-of experiment is used in order to set-up a variety of combinations of geometrical parameters, whereas the Finite Element analysis, performed in ABAQUS, is applied using obtained geometry variations in order to calculate corresponding stress concentration factors. MATLAB is also used for subsequent mathematical modeling in order to obtain appropriate expressions for stress concentration factors. Obtained mathematical models agree well with existing data from literature.

The interaction between the flowing blood and the deforming arterial wall is critical in blood flow dynamics and understanding the role of hemodynamic forces such as wall shear stress in atherosclerosis. Numerical studies have become an invaluable tool in providing this understanding. Unfortunately most of these studies have been based on rigid arterial geometries. These geometries do not take into account the interaction between the flowing blood and the dynamics of the flexible arterial wall. This work addresses these irregularities by using a fluid-structure interaction (FSI) approach in wall shear stress analysis while validating the numerical predictions with analytical solutions and results from flow visualization experiments. Mock arteries used in the physical experiments are made of polyurethane rubber whose properties were determined through a series of material tests. Numerical studies are performed using OpenFOAM-1.2, a 3D CFD solver based on FVM. Preliminary results show significant differences between wall shear stress transients in rigid and flexible geometries.

Atherosclerosis is a chronic medical condition in which thickening and loss in the elasticity of the artery wall leads to impaired blood circulation[1]. Cholesterols and other proliferating cells accumulate at localized regions within the artery wall. This has the effect of stiffening and thickening the wall at that point. The presence of an emerging plaque should effect the deformation of and stresses generated within the artery wall sufficiently so to make it possible to detect this disease whilst still in its early stages. The hypothesis under investigation in this work is that an altered deformation profile, because of stiffening and thickening of the artery wall is an early indicator of the existence of this disease.Copyright © 2007 by ASME

Drop impact resistance of fluid-filled plastic containers is of considerable concern to plastics and containers manufacturers as well as distribution industries utilising containers for transportation of various liquids. This is due to potential failure of the containers following the drop impact and subsequent spillage of the transported liquid. In this work, a combined experimental-numerical study of the problem is presented. Experimental investigation was conducted on 1-litre cylindrical bottles made from polyethylene. Bottles were dropped from a given height onto a concrete floor, and pressure in the contained fluid was recorded during the experiment using pressure transducers. Numerical analysis was performed using Finite Volume based fluid-structure-fracture procedure. Here, Cohesive Zone methodology is introduced into the standard two-system solid-fluid coupling procedure to simulate and predict the failure process. It is shown that numerically predicted pressure and strain histories have good resemblance with experimental results.

Blood flow through arteries represents a very complex, fluid-structure interaction (FSI) problem. Strong coupling between the blood and artery is due to the relatively low stiffness of the artery compared to that of blood. Hence, the pressure exerted by the flowing blood on the artery wall can result in considerable deformations of the artery, and vice-versa, arterial deformations can in turn affect the blood flow. In the present work, the finite volume method is employed to solve the problem where compressible fluid, representing blood, flows in healthy arteries as well as in unhealthy, i.e., partly stiffened arteries. The stiffening of the arterial wall is assumed to be the first key stage in the development of atherosclerosis. The comparison between various deformation profiles of healthy and unhealthy arteries demonstrates significant and measurable differences, in particular in the radial direction. This is hoped to help toward establishing procedures for early diagnosis of the disease.