M. Zidi

Azimuthal shearing and torsion of a compressible hyperelastic and prestressed tube

In this paper, the author studies azimuthal shearing and torsion of a compressible hyperelastic and prestressed tube. The analysis is carried out for a particular elastic material and the governing non-linear equations are solved numerically. The results present the effects of the prestress for different material parameters.

Damaged-bone remodeling theory : Thermodynamical approach

Abstract The bone remodeling process is generally viewed as bone material response to functional demands and muscle attachments by continual process of growth, reinforcement and resorption which occur in living situation. Everyday activities damage bone, and this damage is normally repaired in a continuous process. When an imbalance in this remodeling process occurs, Bones may become more susceptible to fracture. An attempt to establish a relationship between induced microdamage and adaptive bone remodeling is proposed. A thermodynamic theoretical framework is provided as basis for a consistent formulation of bone remodeling involving a chemical reaction and mass transfer between two constituents in presence of microtracks.

Finite torsion and shearing of a compressible and anisotropic tube

Abstract The finite deformation of a hyperelastic, compressible and anisotropic tube subjected to torsion, circular and axial shearing is studied. The analysis is carried out for a class of Ogden elastic material and the governing non-linear equations are solved numerically with the Runge–Kutta method. The solution is used to study the effects of a specific material model on the local volume change and the circumferential stretch ratio.

Buckling and postbuckling of concentric cylindrical tubes under external pressure

Abstract The problem considered involves a structure composed of two concentric and bonded tubes subjected to external and uniform pressure. Compression tests are conducted using structures formed by a thin-walled internal rubber tube and a thick-walled external foam tube. Experimental results are plotted under the form of a bifurcation diagram representing the inner cross-sectional area of the thin tube as a function of pressure. The buckling pressure Pb and the contact pressure Pco are determined from this non linear diagram. A numerical computation by the Finite Element Method (FEM) is used in order to calculate the Euler buckling pressure Pb and the results are compared with experimental data. It is shown that the buckling pressure and the associated buckling mode n, strongly depend upon the elastic and geometrical parameters of both the tubes. The experimental and numerical investigations are also extended to postbuckling behaviour. The contact between the opposite sides of the inner wall is occured with a buckling mode index n = 2, 3. This contact phenomenon is given rise to the discontinuity of a previous diagram and was characterized by the contact pressure Pco.

Finite deformations of fibre-reinforced vascular prosthesis

Abstract We present an mechanical study of a vascular prosthesis subjected to finite radial expansion, torsion and circular shearing. The material strain-energy function is expressed in the form of the fibre-reinforced neo-Hookean. The governing equations are solved analytically and the results present effects of the combined deformation on the stress distributions.