Browsing by Author "Taghite, M."

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    Analysis of elliptical cracks in static and in fatigue by hybridization of green’s functions
    (2009) Hachi, B.K.; Rechak, S.; Haboussi, M.; Taghite, M.; Belkacemi, Y.; Maurice, G.
    A hybrid weight function technique is presented. It consists of dividing an elliptical crack into two zones, then using the appropriate weight function in the area where it is more efficient. The proportion between zones is determined by optimizing two crack parameters (axis ratio and curvature radius). Stress intensity factors are hence computed by a self developed computer code. Static and fatigue loadings are considered. The results found by the present approach are in good correlation with the analytical and experimental solutions (when available) as well as with those obtained numerically by other researchers
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    Computation of stress intensity factor in cracked plates under bending in static and fatigue by a hybrid method
    (2007) Hachi, B.E.K.; Rechak, S.; Haboussi, M.; Taghite, M.; Maurice, M.
    A hybrid weight-function technique is presented. It consists of dividing an elliptical crack into two zones, then using the appropriate weight function in the area where it is more efficient. The proportion between zones is determined by optimizing two crack parameters (axis ratio and curvature radius). Stress intensity factors for plates containing elliptical and semi-elliptical cracks are hence computed by a self developed computer code. Static and fatigue loadings of bending are considered. The results found by the present approach are in good correlation with the analytical solutions (when vailable) as well as with those of other researchers
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    Effects of the modifications of the mechanical properties of the skin on the irrigation of the venous wall by the vasa vasorum
    (2004) Maurice, G.; Rechak, S.; Amor, N.; Taghite, M.
    Abstract. It is well known that the nonlinear mechanical properties and the ordering of the muscular fibres of the media and the adventia restrict the expansion of the vascular wall under an intraluminal pressure. On the young persons, the surrounding tissues of the blood vessels also play a part in the effect of these two layers. Particularly, for the veins of the upper and lower limbs, the skin plays a no unimportant part in the restriction of this expansion. With the age, the tissues may become distended or reduce their thickness and clearly allow to show some vessels which then are less restrained by the surrounding tissues like the skin. The deformation of a vein under the influence of intraluminal pressure modifies the cross-section of its vasa vasorum and thus can alter its irrigation. The nonlinear elasticity of the vein depends, as a first approximation, basically on two structural parameters. In some cases, even a small variation of the parameters (behaviour or composition of the wall) can provoke the flattening of the vasa vasorum and thus lead to a local ischemia. Thus, one can think that a vicious cycle could be initiated. Firstly, a permanent overpressure causes a modification of the local mechanical property of the vein, which, if it is not restrained by the surrounding tissues, leads to a large expansion of the vessel wall and enhance the decrease of the irrigation. Secondly, the irrigation being insufficient, the vein wall looses its elasticity, becomes progressively rigidified and keeps its maximum deformation
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    Fatigue growth of embedded elliptical cracks using paris-type law in a hybrid weight function approach
    (2008) Hachi, B.E.K.; Rechak, S.; Haboussi, M.; Taghite, M.; Maurice, G.
    A hybrid weight function method (HWFM), improving the calculation of the stress intensity factor (SIF) in mode I, has recently been proposed and validated in the static case [B.K. Hachi, S. Rechak, M. Haboussi, M. Taghite, Modélisation des fissures elliptiques internes par hybridation de fonctions de poids, C. R. Mecanique 334 (2006) 83–90]. In the present Note, the hybridization approach is presented for the fatigue crack growth prediction of embedded elliptical crack in infinite bodies. Hence, Paris’s law of crack propagation is incorporated into the developed hybridization-based computer code, along with two degrees of freedom technique for managing the crack evolution and the cracked structure fatigue life. Simulations of the evolution of elliptical cracks (in infinite bodies) of different configurations (ellipse axes ratio, maximum crack advance) corresponding to fatigue and brittle fracture have been conducted. Comparisons with other numerical methods such as the classical weight function method (WFM) or the extended finite element methods (X-FEM) show the pertinence of the HWFM in the treatment of an aspect of fatigue cracking problems
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    Modélisation de fissures elliptiques internes par hybridation de fonctions de poids
    (2006) Hachi, B.E.K.; Rechak, S.; Haboussi, M.; Taghite, M.
    Une méthode améliorant le calcul des facteurs d'intensité de contrainte par hybridation de deux fonctions de poids est présentée et appliquée aux cas de fissures elliptiques internes sous différents chargements. L'hybridation consiste à utiliser l'une ou l'autre des deux fonctions dans la zone de la fissure où la fonction est la plus efficace. La délimitation des deux zones est faite après optimisation du rapport des axes et du rayon de courbure de la fissure. Lors de l'optimisation on cherche à atténuer l'effet des singularités présentes dans les fonctions de poids et à mieux prendre en compte l'influence de la courbure de l'ellipse