Papers by Mohamed BENGUEDIAB
Materials Research, 2012
Hole cold expansion (HCE) is an effective method to extend the fatigue life of mechanical structu... more Hole cold expansion (HCE) is an effective method to extend the fatigue life of mechanical structures. During cold expansion process compressive residual stresses around the expanded hole are generated. The enhancement of fatigue life and the crack initiation and growth behavior of a holed specimen were investigated by using the 6082 Aluminum alloy. The present study suggests a simple technical method for enhancement of fatigue life by a cold expansion hole of pre-cracked specimen. Fatigue damage accumulation of cold expanded hole in aluminum alloy which is widely used in transportation and in aeronautics was analyzed. Experimental tests were carried out using pre-cracked SENT specimens. Tests were performed in two and four block loading under constant amplitude. These tests were performed by using two and four blocks under uniaxial constant amplitude loading. The increasing and decreasing loading were carried. The experimental results were compared to the damage calculated by the Miner's rule and a new simple fatigue damage indicator. This comparison shows that the 'damaged stress model', which takes into account the loading history, yields a good estimation according to the experimental results. Moreover, the error is minimized in comparison to the Miner's model.
Revue des composites et des matériaux avancés, Aug 31, 2013
Généralement, le stade II de la propagation de fissure de fatigue (FCP) est décrit par le modèle ... more Généralement, le stade II de la propagation de fissure de fatigue (FCP) est décrit par le modèle de Paris- Erdogan. L'approche phénoménologique de la propagation de fissure de fatigue à travers ce modèle suggère l'existence d'une relation linéaire entre ces deux paramètres. Le but général de ce travail est d'étudier les effets des paramètres de chargement sur la propagation de fissure de fatigue dans le cas d'un acier 12NC6 soumis à un traitement thermique pour obtenir des valeurs de limites d'élasticité différentes. La corrélation entre les paramètres C et m a été examinée et comparée avec les résultats donnés par la littérature. La variabilité de ces deux paramètres a été analysée pour prédire la durée de vie des structures.
Annales de Chimie - Science des Matériaux
This study presents an experimental and computational analysis of fracture under mixed-mode condi... more This study presents an experimental and computational analysis of fracture under mixed-mode conditions in aluminum alloy AA3003 using the Compact Tension Shear CTS specimen, both not welded and Friction stir welded. Mixed-mode fracture experiments were performed using the CTS specimen and an ARCAN loading device based on Richard's principle suitable for mixed-mode. The approach of linear elastic fracture mechanics allows for a better understanding of mixed-mode failure and the evaluation of the stress intensity parameters KI and KII. The variation of the stress intensity factor KI, KII is influenced by the pre-cracks length. The comparison between experimental results and the numerical results of simulation shows that there is a good agreement between these results.
A new refined hyperbolic theory taking into account the transverse shear effect is proposed to an... more A new refined hyperbolic theory taking into account the transverse shear effect is proposed to analyze the static behavior of thick plates in functionally graduated materials (FGM). The proposed model uses a new displacement field using only four unknowns determining the equilibrium equations, using the Hamilton principle. This theory contains only four variables unlike other plate theories. The nullity of transverse shear stresses at the upper and lower surfaces of the plate is satisfied in this model. These material properties of the FGM plate vary according to a distribution of the power law in terms of volume fraction of the constituents; one can conclude that this theory is effective and simple for the analysis of the static response of the FGM plates.
In this paper we present the influence of residual stresses on the behavior of fatigue cracks und... more In this paper we present the influence of residual stresses on the behavior of fatigue cracks under thermo-mechanical loading. Propagation modeling is performed using the global stress intensity factor approach, which describes the simultaneous influence of residual stress field and applied stress on crack propagation. The residual stresses are generated by a thermal loading. These stresses are the result of incompatibilities of deformation related to the heterogeneity of the plastic deformation. They will be superimposed on the loading of fatigue and thus modify the average stress. These residual stresses relax under the effect of fatigue loading, by keeping the crack closed or open, according to the stress cycle.
In this paper an analysis of the evolution of a semi-elliptical crack located at different positi... more In this paper an analysis of the evolution of a semi-elliptical crack located at different positions of the wall of an HDPE pipeline under internal pressure is made. The three-dimensional finite element method is used to calculate the integral J. The <em>J </em>integral is important in the extreme positions on the contour of integration. When the ratio (a / t) reaches a critical value (a / t = 0.6), the effect of crack depth becomes important. It's also shown that for low values of the opening angle of the curve, the crack tends to be propagated from the position<em> 1</em>. The transverse cracks have a lower risk that the axial cracks and then the cracks into interior of the wall of the pipe are more dangerous than the cracks external.
This study reports an empirical investigation of fatigue crack initiation and propagation in 2024... more This study reports an empirical investigation of fatigue crack initiation and propagation in 2024 T351 aluminium alloy using constant amplitude loading. In initiation stage, local strain approach at the notch was used and in stable propagation stage NASGRO model was applied. In this investigation, the flat plate of double through crack at hole is used. Based on experimental results (AFGROW Database), effect of stress ratio, R, is highlights on fatigue initiation life (FIL) and fatigue crack growth rate (FCGR). The increasing of dimension of hole characterizing the notch effect decrease the fatigue life.
Synthese, 2008
The use of riveting as an assembly technique, especially in the aeronautical construction, requir... more The use of riveting as an assembly technique, especially in the aeronautical construction, requires the implementation of several holes in aluminium alloy sheets. This leads to an inhomogeneous stress and strain fields' distribution and to stress localization in the drilled zones which will be affecting the fatigue life of 2024-T3 aluminium alloy. In addition, the machining process used for drilling can increase or decrease the fatigue life of materials. This paper presents results of an experimental study which main objective is to determine the drilling procedure that least affects the fatigue life and to show the role of the residual stresses introduced by each process on the fatigue behaviour of material. For that, four drilling procedures are compared in fatigue: Direct drilling bit of the desired diameter, drilling a small diameter hole called a pilot hole in the rivet hole location prior to drilling the final diameter using a reamer, water jet and finally punching. Hole’s...
Mechanics and Mechanical Engineering, 2017
Several theoretical models have been proposed to predict the fatigue crack growth range (FCGR) pr... more Several theoretical models have been proposed to predict the fatigue crack growth range (FCGR) process using solid mechanics, based theoretical tools and basic or fundamental mechanical properties. Moreover crack growth is linked to the existence of a plastic zone at the crack tip when the formation and intensification are accompanied by dissipation of energy. The overall objective of the present research is to develop, verify, and extend the computational efficiency of the model for fatigue crack growth range (FCGR) function by elastic properties, cyclic hardening and celebrated Paris law. The influence of the variability to elastic properties (Young’s modulus E, tensile strength σe and cyclic hardening exponent n’) is a necessary analysis in this work. The predictions of the proposed model were compared with experimental data obtained by [1].
The importance of developing an analysis of the flexural behavior of beams is related firstly to ... more The importance of developing an analysis of the flexural behavior of beams is related firstly to the use of beams as a basic element in the realization of structures, and also to characterize the mechanical properties of laminates and sandwich materials from bending test performed on specimens shaped beams. Determining the mechanical behavior of pavement materials leads to calculate the distribution of stresses and strains in the pavement the rigidity of the materials, in order to determine the thickness to set up according to the resistance of these materials to different damage mechanisms, depending on climate and traffic. Comparison of the mechanical behavior of materials allows making a selection of the type of materials and interventions based on their performance. In addition, knowledge of the mechanical behavior of materials permits to develop specifications based on the physical properties of these materials and selection criteria for the type of intervention based on a cost...
World Academy of Science, Engineering and Technology, International Journal of Civil and Environmental Engineering, 2015
The behavior of thin rectangular perforated plates under the action of uniform compressive deform... more The behavior of thin rectangular perforated plates under the action of uniform compressive deformation is studied using finite element analysis. The central holes are either circular holes or square holes. The effects of plate-support conditions, plate aspect ratio, hole geometry, and hole size on the buckling strengths of the perforated plates was studied. The results show that for the same plate weight density, the buckling strengths of the plates with square holes generally surpass those of the plates with circular holes over the range of hole sizes.
Steel and Composite Structures, 2018
Mechanics and Mechanical Engineering, 2017
This paper presents a study about the effects of initial porosity and stress triaxiality on void ... more This paper presents a study about the effects of initial porosity and stress triaxiality on void growth and coalescence in High-density polyethylene (HDPE) material. Two approaches are used to modulate the representative material volume: The first one is a unit cell with a spherical void at the center (Voided cell model), and the second is a unit cell containing the same void fraction of volume and obeying to the constitutive relation of Gurson-Tvergaard-Needelman (GTN model). Detailed analyses of finite element gave us: the equivalent stress-strain response, the void growth and coalescence behavior of the representative material volume. Results show that the stress triaxiality and the initial void volume fraction are strongly effective and depended on.
Le but de notre travail est la modelisation de l'endommagement d'un polymere (Polypropyle... more Le but de notre travail est la modelisation de l'endommagement d'un polymere (Polypropylene) en utilisant la methode des elements finis et les concepts de la mecanique de la rupture basee sur des approches locales. L’utilisation du modele Gurson Tvergaard-Needleman, nous a permis de modeliser le comportement d’endommagement du Polypropylene, qui est decrit comme etant du a la croissance de cavites
The cyclic hardening (stress-strain) curve is useful in the design of structural components that ... more The cyclic hardening (stress-strain) curve is useful in the design of structural components that are subjected to cyclic plastic deformation; it is a very important phenomenon that reflects the elastic-plastic material behavior. This work is a contribution to the modeling of low cycle fatigue at a plastic strain imposed for three aluminum alloys (6061-T6, 2024-T3 and 7075-T6) using the ANSYS finite element method. This model has allowed the mechanical characterization in tension and compression of the materials studied and establish their monotonous and cyclic hardening curves. The results are used to determine the constants of Basquin and cyclic hardening parameters. The simulated results are verified against experimental results available in literature.
Materials, methods & technologies, 2014
In this study, the finite element method is used to analyze the effect of a geometric discontinui... more In this study, the finite element method is used to analyze the effect of a geometric discontinuity on the fracture behaviour of polymer material (High-Density-Polyethylene; HDPE). The effect of the temperature parameter on the distribution of stresses and strains at the notch (geometric discontinuity) has been studied. The results obtained numerically show a good correlation with experimental results. The Rice-Tracey (RT) model is used to reproduce the macroscopic mechanical behavior of the HDPE material in terms of stress versus strain for different temperature level.
Welding is used to realize permanent assembly in mechanical structures to assure the continuity o... more Welding is used to realize permanent assembly in mechanical structures to assure the continuity of the parts to be assembled contrary to the other assembly techniques which have physical or chemical discontinuities. Generally, crack evolution depends on several intrinsic and extrinsic parameters of material. The aim of this work is to analyze the severity of crack defects on the mechanical behavior of Welded joints. The cracks are considered located in the weld metal. The J-integral method was used to analyze the fracture behavior of these structures by the two-dimensional finite element method using Cast3M code. The effect of the mechanical properties, the mismatching and the crack size on the J-integral values was highlighted. A good correlation between the FEM simulations and the literature analysis results was observed. We note that the loading mode affects directly the J-integral value and consequently on the mechanical behavior of the welded joint.
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Papers by Mohamed BENGUEDIAB