Browsing by Author "Boutoutaou, Hamid"

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Axisymmetric frictionless contact between an elastic layer thickness and a circular base under a rigid punch
(SAGE, 2023) Guerrache, Fadila; Boutoutaou, Hamid; Hachemi, Madjid
The study presented in this work deals with analytical methods for an axisymmetric problem of an elastic layer partially reposing on a rigid circular base, and is indented along the upper surface with a rigid punch. The contact between the medium and the base is smooth. This boundary value problem is transformed into a system of dual integral equations. In contrast to the classical approach consisting in resolving the corresponding Fredholm equation of the second kind, the latter equations are obtained from an infinite algebraic system of simultaneous equations, where the particular case (Formula presented.) is verified. The results of this system are also obtained numerically. The normal displacement, normal stress, and the stress singularity factor are given analytically and shown graphically with discussion. By comparison with those predicted by the finite element method, the accuracy of the numerical method is approved
Effect of form defect in Thin-Walled cylinder assembly
(Springer, 2023) Bedlaoui, Allal; Boutoutaou, Hamid
Shrink-ft assemblies have been used to ofer a more robust running surface for wooden wheels for a long time. Generally, the two parts are cylindrical or conical. Shrink-ft is now an operation that involves creating contact between two cylinders, there is no third party, and this is good economically. It’s employed in a variety of industries, including automotive, aerospace, oil and gas, and train wheels. To do this operation, the inner cylinder’s outer radius must be greater than the outer cylinder’s inner radius, that diference between them is called ’interference’, the latter is being important in the assembly because it contributes to increasing the resistance of the assembly. There are three ways to do this: the frst by heating the outer cylinder until it expands, the second by cooling the inner cylinder until it shrinks and the third way is to realize the ftting under a press. When two cylindrical components are assembled by pushing or shrinking one onto the other, at the interface between the two matching parts, a contact pressure and friction force is formed. We study a shrink-ft assembly made up of two hollow cylinders in this paper, taking into account that the contact surfaces are not perfect but contain form defects, we try to know the efect of form defects and their role in the cohesion of the assembly using numerical simulation
Effect of form defect on pipe surfaces subjected to pressure at the assembly point
(2022) Bedlaoui, Allal; Boutoutaou, Hamid
Shrink-fit assemblies have been used to offer a more robust running surface for wooden wheels for a long time. Generally, the two parts are cylindrical or conical. Shrink-fit is now an operation that involves creating contact between two cylinders, there is no third party, and this is good economically. It’s employed in a variety of industries, including automotive, aerospace, oil and gas, and train wheels. To do this operation, the inner cylinder’s outer radius must be greater than the outer cylinder’s inner radius, that difference between them is called “interference,” the latter is being important in the assembly because it contributes to increasing the resistance of the assembly. There are three ways to do this: the first by heating the outer cylinder until it expands, the second by cooling the inner cylinder until it shrinks, and the third way is to realize the fitting under a press. When two cylindrical components are assembled by pushing or shrinking one onto the other, at the interface between the two matching parts, a contact pressure and friction force is formed. In this paper, we study shrink-fit assembly consisting of two thin hollow cylinders with the inner cylinder subjected to pressure, this actually represents what happens to the tubes at the assembly point (where the tube meets the other), taking into account that the surfaces are not perfect but are wavy, meaning they contain form defects. Using numerical simulation, we want to know the effect of the form defect on the distribution of stresses, deformations, and assembly resistance, and is this effect positive? or not
Elasticity: course and resolved exercises
(University of M’Hamed Bougara Boumerdes: Faculty of Technology, 2023) Boutoutaou, Hamid
This handout of lessons and exercises was written for 3rd year undergraduate students in mechanical engineering and civil engineering. It is presented to them immediately after the course in mechanics of continuous media and that of the resistance of materials from which it is very largely inspired, by its notions, concerning tensors, as well as its methods, describing the laws of behavior which make it possible to establish the equations linking stresses to deformations (generalized Hooke's laws), in the field of isotropic linear elasticity. It constitutes course support for undergraduate students in the same field. This course is made up of five chapters and two appendices. At the end of each chapter, solved exercises are covered. They allow all students to better understand the different physical phenomena (mechanical behavior) studied in their school curriculum and to resolve the problems encountered later in industry
Influence de l'effort axial sur l'instabilité élastique et élastoplastique des structures planes
(2003) Boutoutaou, Hamid
L'objet de ce travail est de mener une étude sur l'analyse de l'instabilité et du comportement des structures planes sous l'influence de l'effort axial. L'étude utilise la méthode d'analyse de la stabilité incrémentale qui suppose la linéarité des déplacements au voisinage d'une position d'équilibre non-linéaire, l'approche utilisée dans la formulation du problème est basée sur la méthode des éléments finis ; ainsi dans chaque état d'équilibre stable, nous obtenons un système d'équations non linéaires dépendant de l'effort axial. Cependant, la connaissance de la valeur de cet effort, transforme ce système en un système d'équations linéaires dont la résolution est obtenue par la méthode d'élimination de GAUSS. Les programmes élaborés sont en langage FORTRAN et sous forme de variantes. Ils présentent les combinaisons possibles des différents facteurs affectant la stabilité des structures
Influence of form defect on the mechanical behavior and stress intensity factor of shrink-fitted thick-walled cylinders
(Sciendo, 2022) Boutoutaou, Hamid; Chebbab, Brahim; Belmessous, Abdelmounaime
In this research work, the finite element software, ABAQUS is used to study by simulations the influence of form defect on mechanical behavior of a shrink-fitted assembly presenting internal radial cracks. Under the action of contact pressure induced by the tightening between two cylinders, these cracks resulting from incorrect assembly operations or materials elaboration defect, can be harmful to the assembly. Various simulations were carried out in two modeling cases, taking into account the geometric parameters of defect (amplitude Df), of cylinders (thickness t) and of cracks (length a, ratio a/t). Another important parameter such as the tightening was also considered in the modeling. The first modeling relates to the case with defect, external cylinder presents an oval (elliptical) form defect and internal radial cracks. The other concerns the perfect equivalent case (without form defect). The comparison of results obtained by two models shows that form defect modifies the uniformity of equivalent stresses distribution in cylinders and increases the value of stress intensity factor (SIF) KI in cracks. Defect amplitude and tightening significantly influence the value of equivalent stress and that of stress intensity factor (SIF) KI
Methodology for a computer-aided design of shrink fits that considers the roughness and form defects of the manufacturing process
(Springer, 2015) Boutoutaou, Hamid; Fontaine, J. F.
Modeling of interference fits taking form defects of the surfaces in contact into account
(Elsevier, 2011) Boutoutaou, Hamid; Bouaziz, M.; Fontaine, J.F.
The technique of assembly by shrink fit is increasingly used today. However, the methodology of parts sizing has not changed in 50 years. Assembled parts are assumed to have accurate dimensions and very low form defects. This has the disadvantage of increasing the cost of parts production. To reduce manufacturing costs, the study of the influence of form defects on the characteristics of assembly strength is essential. Taking default form into account assumes that the tightening (difference between the diameters of the shaft and the bore) is defined. In the case under consideration, the tightening depends locally on the radius. Two definitions of the tightening are proposed: maximum tightening and mean tightening. It is shown that the form defect is not detrimental to the assembly strength: the mean pressures are nearly equivalent to the classical case of surfaces without defects. Various finite element simulations were performed. The influence of the value and the type of defect have been studied for conventional tightening (elastic materials) and more intensive tightening (elasto-plastic behavior) in the case of axisymmetrical and non-axisymmetrical parts. The theoretical results correlate well with those obtained through experiments. However, for intensive tightening, the behavior of the roughness is not negligible
Modelling of interference fits with taking into account surfaces roughness with homogenization technique
(Elsevier, 2013) Boutoutaou, Hamid; Bouaziz, Mohamed; Fontaine, Jean-François
Optimization of contact surfaces in assembly in the presence of form defects and interference
(Springer Nature, 2023) Bedlaoui, Allal; Boutoutaou, Hamid; Guerrache, Fadila
Shrink-fit assembly is one of the most important mechanical assembly methods. It has been used for many years because it is economical due to it needing only two components an axis and a hub, as the outer diameter of the axis is greater than the inner diameter of the hub and the difference between them is the “interference.” The shrink-fit assembly is used in several fields such as the manufacture of aircraft, cars, and connecting oil and gas pipelines. Assembly is achieved either by heating the hub and cooling the axis or by force. When assembling, contact pressure is formed on the contact area between the axis and the hub. Usually, the contact area is considered perfect, but in reality, it contains defects that vary in amplitude and number. In this article, we study the role of the form defect and interference in the 3D assembly by studying its effect on the extraction force and assembly coherence, with use numerical simulation to confirm this. Component separation experiment was applied to validate the simulation results
Support de Cours et Exercices Méthode des éléments finis
(Faculté de technologie département génie mécanique, 2022) Boutoutaou, Hamid
Ce polycopié intitulé « support de cours et exercices méthode des éléments finis » a été rédigé à l’intention des étudiants en master I génie mécanique. Il leur est présenté immédiatement après les cours de mécanique des milieux continus, mécanique rationnelle et celui de la résistance des matériaux dont il s’inspire très largement, par ses notions, concernant les torseurs, les tenseurs, ainsi que ses méthodes décrivant les lois de comportement qui permettent d’établir les équations reliant les contraintes aux déformations (Lois de Hooke généralisée), dans le domaine de la mécanique des solides. Il constitue aussi, un support de cours pour les étudiants en masters I de la filière génie civil et une base pédagogique aux enseignants chargés cours......
Ultrasonic wave simulation in shrink-fit assembly for the estimation of stress at the contact interference
(SAGE Publications Inc, 2024) Belmessous, Abdelmounaime; Boutoutaou, Hamid
The investigation of stress distribution in an interference fit contact region is essential information required in fatigue and wear calculations to determine design life, regrinding requirements, and maintenance schedules. The aim of this work was to use ultrasound to non-destructively determine stress in the shrink-fit assembly, with the acoustoelastic theory. This one is based on the dependence of the propagation velocity of the ultrasonic wave with the stress state in the material. When a material is subjected to stress, there is a variation of the propagation velocity of the ultrasonic wave. Three methods have been initiated to ensure that the results will be more real, the first is the analytical calculation using thick-walled cylinder theory and Lamé formulation, then a numerical modeling of the contact between the assembled parts using finite element analysis and the third one is using elastic wave simulation and acoustoelastic theory in order to determine the value of the stress distribution at the interference region.