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1
Content available remote Study of void growth and coalescence in HDPE material: a numerical investigation using computational voided cells
Cherief M. N. D., Benguediab M., Elmeguenni M., Reffas A.
Mechanics and Mechanical Engineering
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2017
|
Vol. 21, nr 3
467--483
EN
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 relations 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.
2
Content available remote Propagation of cracks in reinforced concrete beams cracked and repaired by composite materials
Benarbia D., Benguediab M.
Mechanics and Mechanical Engineering
|
2017
|
Vol. 21, nr 3
591--601
EN
Strengthening and repairing existing reinforced concrete structures is often more economical and sustainable than rebuilding them. Today the most commonly used techniques based on reparation by externally bonded Carbon Fiber Reinforced Polymers (CFRP). However, bonding concrete beams, particularly damaged beams, suffer from the pre-existing of open cracks at the bottom face of the beams. This paper presents an investigation by finite element method using the general purpose FE software Abaqus to study the flexural behavior of initially damaged concrete beams repaired with FRP plates. In this study, it is aimed to simulate the phenomenon of propagations of cracks where the beam is initially loaded to introduce damage, then, after bonding the FRP plates. The linear elastic fracture mechanics (LEFM) approach is adopted to pursue the stress intensity factor’s evolution in 3-points bending before and after reparation of RC beams. Many parameters were taken account, such us the thickness of the adhesive layer and reinforcing plate, the stiffness, and young’s modulus. Results were identified and discussed.
3
Content available remote Numerical study of the mechanical behavior and fatigue in a weld bead by friction stir for a 6082-T6 aluminum alloy
Kambouz Y., Benguediab M., Bouchouicha B.
Mechanics and Mechanical Engineering
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2017
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Vol. 21, nr 1
67--83
EN
The process of friction stir welding is a significant advance in the field of research on the Friction welding technique known for several decades. This assembly technique has obvious originality since welding is performed in the solid state, which can help eliminate birth defects related to solidification phase compared to conventional welding. The numerical modeling of this type of process is complex, not only in terms of the variety of physical phenomena which must be considered, but also because of the experimental procedure that must be followed in order to verify and validate numerical predictions. In this work, a finite element model is proposed in order to simulate the crack propagation under monotonic loading in different areas of the weld seam of a specimen CT-50 aluminum alloy 6082-T6. Microhardness tests were performed to characterize the Vickers hardness profile in the vicinity of the weld area. Friction stir welding process leads to a decrease of the static mechanical properties relatively to base material. Detailed examination revealed a hardness decrease in the thermo mechanically affected zone and the nugget zone average hardness was found to be significantly lower than the base alloy hardness. Welded specimens show significantly lower lives than base material.
4
Content available remote Influence of the variability of the elastics properties on plastic zone and fatigue crack growth
Kebir T., Benguediab M., Imad A.
Mechanics and Mechanical Engineering
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2017
|
Vol. 21, nr 4
919--934
EN
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 e 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].
5
Content available remote Buckling of rectangular plates with different central holes
Benguediab S., Kettaf F. Z., Benguediab M.
Mechanics and Mechanical Engineering
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2017
|
Vol. 21, nr 4
885--895
EN
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.
6
Content available A Model for Fatigue Crack Growth in the Paris Regime under the Variability of Cyclic Hardening and Elastic Properties
Kebir T., Benguediab M., Imad A.
Fatigue of Aircraft Structures
|
2017
|
Iss. 9
117--135
EN
Over the last 60 years, several models have been developed governing different zones of fatigue crack growth from the threshold zone to final failure. The best known model is the Paris law and a number of its based on mechanical, metallurgical and loading parameters governing the propagation of cracks. This paper presents an analytical model developed to predict the fatigue crack propagation rate in the Paris regime, for different material properties, yield strength (σy), Young’s modulus (E) and cyclic hardening parameters (K’, n’) and their influence by variability. The cyclic plastic deformation at a crack tip or any other cyclic hardening rule may be used to reach this objective, for to investigate this influence, these properties of the model are calibrated using available experimental data in the literature. This FCGR model was validated on Al-alloys specimens under constant amplitude load and shows good agreement with the experimental results.
7
Content available remote Modeling and Simulation Baed Analysis of Centrifugal Pump Volute Design Parameters by Finite Element Method
Belbachir S., Allali A., Lousdad A., Benguediab M.
Mechanics and Mechanical Engineering
|
2016
|
Vol. 20, nr 4
417--424
EN
The performance of pumps are influenced by many factors among which the geometric configuration of the volute. The role of the volute in a centrifugal pump is the transformation of the kinetic energy into pressure with a minimum of losses. The volute is a pump element which is difficult to modify. It must be able to be adapted to impeller with different dimensions. The objective of this work is to investigate by numerical simulation the Von Mises stress distribution and displacements in volutes of different dimension in diameters and width of a centrifugal pump. The study is carried out using finite element method on a three dimensional configuration using ABAQUS code. Only a few attempts of numerical analyses of the mechanical behavior of volute are made. This element plays an important role in the pump adaptation for a given operating conditions by adjusting its dimensions. This activity is conditioned by a good understanding of 418 Belbachir, S., Allali, A., Lousdad, A. E. and Benguediab, M. the design process of the volutes. The obtained results show the modifications of the diameter and the width of the volute have an effect on the values of Von Mises’ stresses and on the displacements. The stresses and displacements reach their maximum with increasing diameters and are inversely for the increase in the width. These dimensional modifications can act indirectly on the clearance at the bec and also on the clearance between the volute exit and the impeller. These are functional clearances which allow the determination of the operating characteristics of centrifugal pumps. With these results substantial improvement on the pump design can be made.
8
The fretting fatigue of the bolted assemblies
Benhamena A., Aminallah L., Aid A., Benguediab M., Amrouche A., Benseddiq N.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
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2011
|
z. 99
17-17
EN
One of the principal failures of bolting assemblies is the fretting. The combi- nation of vibration and service load can introduce the damage of fretting fatigue on the contact surfaces of the assembly which trend to evoke a nucleation of crack and then the structure fracture. Contact pressure or clamping force and displacement at the interface or relative slip are two important factors which control the fretting wear and the fretting fatigue. This paper describes the effect of clamping force (tightening torque) on the fretting fatigue behavior of bolted assemblies.
9
Effect of hardening induced by cold expansion on damage fatigue accumulation and life assessment of aluminium alloy 2024
Bouguenna B., Aid A., Bendouba M., Benguediab M., Amrouche A.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
|
2011
|
z. 99
18-19
EN
Hole cold expansion (HCE) is an effective method to prolong the fatigue life of mechanical structures because it introduces residual compressive tangen- tial stresses around the expanded hole. The enhancement method of fatigue life and the crack initiate and growth behavior of a holed specimen was investigated by using the 2024 Aluminum alloy. The purpose of present study is to propose a simple technical method for enhancement of fatigue life in a hole cold expansion of pre-cracked spec- imen. Fatigue damage accumulation of cold expanded hole in aluminum alloys used in land transportation components was investigated. Tests were carried out using pre-cracked SENT specimens. Tests were performed in two and four block loading under constant amplitude. Two sequences were com- pared. The increasing and the decreasing magnitude were compared. The experi- mental results were compared to the damage calculated by the Miner's rule and a new simple fatigue damage indicator. This comparison shows that the ‘model of the mage stress’, which take into account of the loading history, yields a good estimation of the experimental results. Moreover, the error is minimized in comparison to the Miner's model.
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