Latest issue - Internationial Review of Mechanical Engineering (IREME)

Home>Products>Journal and Reviews>I.RE.M.E.>Latest issue

International Review of Mechanical Engineering - January 2007 - Papers

Stick-Slip Chaos Prediction in Self-Excited Two-Dof Hysteretic Systems with Friction, by J. Awrejcewicz, L. P. Dzyubak
Loss Correlations for Developing Turbulent Pipe Flow, by A. C. Benim, F. Gul, E. Pasqualotto
Performance Improvement of Adsorption Desalination Plant: Experimental Investigation, by I. I. El-Sharkawy, K. Thu, K. C. Ng, B. B. Saha, A. Chakraborty, S. Koyama
The Response of Rotating Machines on Viscoelastic Supports, by M. I. Friswell, J. T. Sawicki, D. J. Inman, A. W. Lees
Design of Passive Defense Structures in Coastal Engineering, by D. Isèbe, P. Azérad, F. Bouchette, B. Mohammadi
Buckling and Vibration of Stiffened Plates, by G. M. Vörös
Dynamics of a Five-Degree-Of-Freedom Torsional System with Dry Friction Path and Clearance Nonlinearity, by Y. Driss, T. Fakhfakh, M. Haddar
Dynamic Behaviour of a Simplified Gearbox: Study of the Structure-air Cavity Coupling, by M. Maatar, S. Bouaziz, T. Fakhfakh, M. Haddar
Chatter Prediction Using Dynamic Simulation, by E. Rivière, E. Filippi, P. Dehombreux
Modelling of the Wear of Some Tooling Materials, by A. Hebbar, D. Kaïdameur, D. Ouinas
Numerical Investigations on the Melted Bath Movements During Deep Penetration Laser Welding, by E. H. Amara
Evaluation of the Stress Intensity Factor in a Structure Repaired with an Elliptical Composite Patch, by D. Ouinas, A. Hebbar, J. Viña
Determination of Glass Mechanical Characteristics by Instrumented Indentation, by A. Chorfa, M. Hamidouche, M. A. Madjoubi, F. Petit
Simulation of the Effect of the Paddle Agitator Height on the Hydrodynamic Behaviour in an Agitated Vessel, by M. Bouzit, L. Benali, M. Hachemi
First and Second Order Turbulence Closure for Bubbly Flows, by J. Chahed, G. Bellakhel
Prediction of CO₂ in the Exhaust of C.I. Engine Using Emission Model, by A. A. Pawar, R. R. Kulkarni, J. B. Sankpal

International Review of Mechanical Engineering - Papers

Stick-Slip Chaos Prediction in Self-Excited Two-Dof Hysteretic Systems with Friction
by J. Awrejcewicz, L. P. Dzyubak

Abstract - In this work equations of motion of self-excited 2-DOF hysteretic systems with Coulomb and viscous frictions are presented and reduced to a dimensionless form for the cases of double Masing, double Bouc-Wen and hybrid hysteretic devices. Chaos is quantified using the analysis of wandering trajectories. Conditions for the occurrence of chaotic behavior are found in the planes of maximal static friction forces of both oscillators versus belt velocity. The evolution of the chaotic regions depending on the hysteretic dissipation values is presented.

Keywords: 2-dof hysteresis, stick-slip chaos, parametric spaces.

Loss Correlations for Developing Turbulent Pipe Flow
by A. C. Benim, F. Gul, E. Pasqualotto

Abstract - Loss correlations for the developing incompressible turbulent flow in smooth pipes are obtained by means of computational fluid dynamics (CFD) analysis. In the first part of the investigation, a validation study is performed using different k-e turbulence models and comparing the results with the available experimental data. Subsequently, incompressible turbulent developing flows in smooth pipes are analyzed for Reynolds numbers ranging from 2x10⁴ to 2x10⁷. Two different entry geometries are investigated: an entry with a top-hat profile, and an entry from a large plenum via a sudden area contraction. Computational grids are generated based on grid independency studies and paying special attention to obtain optimal y⁺ values for the near-wall cells. In numerical modeling, second-order accurate discretization schemes are used for all variables. Based on CFD predictions, diagrams are developed, which express the pipe friction factor as a function of Reynolds number and non-dimensional pipe length, for different entry geometries.

Keywords: Turbulent Developing Pipe Flow, Loss Correlations, k-e turbulence model, CFD.

Performance Improvement of Adsorption Desalination Plant: Experimental Investigation

by I. I. El-Sharkawy, K. Thu, K. C. Ng, B. B. Saha, A. Chakraborty, S. Koyama

Abstract - This article deals with the experimental investigation of a four-bed adsorption desalination (AD) plant working at a relatively high evaporation temperature. The effect of heat source temperature and adsorption/desorption cycle time on the system performance in terms of specific daily water production (SDWP) and performance ratio (PR) is experimentally studied. Owing to the higher evaporation temperature, SDWP of the plant is increased by two folds, to about 8.2 m³ of water/ton-adsorbent per day. Further improvement is also achieved by using mass recovery scheme without significant changes to the AD plant.

Keywords: Adsorption, Desalination, Potable water, Silica gel-water.

The Response of Rotating Machines on Viscoelastic Supports

by M. I. Friswell, J. T. Sawicki, D. J. Inman, A. W. Lees

Abstract - Damping in the stator of a rotating machine is able to reduce the unbalance response, and increase the speed where the stability limit is reached. A convenient method to introduce damping is to support the bearings on viscoelastic elastomeric supports. This successfully adds damping but makes the analysis considerably more difficult. Viscoelastic materials have properties that depend on frequency and temperature. The determination of the run-up or run-down response of a linear machine at a constant temperature is quite straight-forward based on measured material characteristics. However the introduction of transient and non-linear effects, temperature changes and model uncertainties makes the analysis difficult. This paper uses the internal variable approach to model the viscoelastic material for the transient dynamic responses, and includes an energy dissipation model. An example of a turbo molecular pump is given, and the difficulty in balancing such machines is demonstrated.

Keywords: Viscoelastic, Machine, Internal Variables, Thermal effects.

Design of Passive Defense Structures in Coastal Engineering

by D. Isèbe, P. Azérad, F. Bouchette, B. Mohammadi

Abstract - This paper aims to show that shape optimization can be efficiently applied to coastal engineering. This is a feasibility study for the design of defense structures for wave attenuation in deep water and against sandy beach erosion. Hence, we consider short wave propagation on a constant depth toward a vertical wall or sea cliff and long wave propagation in a domain with slow but arbitrary depth variations. The governing equations are either based on the Helmholtz wave propagation model or on a parabolic nonlinear refraction/diffraction model in shallow water. In each case, the shape of defense structures is modified in order to minimize a pre-defined cost function taking into account the strength (energy) of the water waves.

Keywords: Shape design, global optimization, water wave propagation, scattering, coastal engineering, beach erosion.

Buckling and Vibration of Stiffened Plates

by G. M. Vörös

Abstract - The buckling and dynamic characteristics of stiffened plates subjected to dead loads are studied using the finite element method. In structural modeling, the plate and the stiffener are treated as separate elements where the displacement compatibility transformation between these two types of elements takes into account the constraint torsional warping effect in the stiffener. The development is based on a general beam theory, which includes the effect of flexural-torsion coupling, constrained torsion warping, and shear center location. The virtual work principle includes the second order terms of finite beam rotations. Numerical tests are presented to demonstrate the importance of torsion warping constraints.

Keywords: Finite element, Stiffener, Free vibration, Buckling load, Constraint torsion.

Dynamics of a Five-Degree-Of-Freedom Torsional System with Dry Friction Path and Clearance Nonlinearity

by Y. Driss, T. Fakhfakh, M. Haddar

Abstract - In this paper a clutch torsional model having five degree of freedom and including several kinematic non linearities is studied. Three types of nonlinearity are considered. Smoothened Coulomb friction formulations and smoothened clearance non-linear functions are applied to the non linear system. The differential governing equations are numerically solved by Runge Kutta method, given harmonic torque excitation and a mean load. First, dynamic behaviour analysis shows that the conditioning factors σ₂ associated with the smoothened friction model and clearance non linear functions must be carefully selected. Then, effects of the saturation friction torque T_sf, the clearance of the splines (b₂) and the stiffness K₁ are numerically investigated.

Keywords: Clutch, splines, friction shoes.

Dynamic Behaviour of a Simplified Gearbox: Study of the Structure-air Cavity Coupling
by M. Maatar, S. Bouaziz, T. Fakhfakh, M. Haddar

Abstract - The main objective of this work is the analysis of vibro-acoustic behaviour of gear-shafts-housing system coupled to an air cavity. The housing is modeled by five rigid faces and an elastic one. The gear pair is modeled by two rigid cylinders connected by an elastic link named time variation mesh stiffness. The shafts are discretized using beam finite elements with two nodes and six d.o.f. by node. The six faces of the housing shut in an air cavity. This study requires the establishment of the functional formulation of the coupled system fluid-structure in term of displacement for the structure and pressure for the fluid. Modal approach, based on the pressure modal decomposition, permits the determination of eigen frequencies and modes of coupling system and the resolution of dynamic equations projected on a reduced modal basis. This model analysis was performed using the STRU finite element program. The equations of motion are integrated in time by using implicit Newmark’s scheme.

Keywords: Gearbox, air cavity, shell, plate, dynamic behaviour, spectrum.

Chatter Prediction Using Dynamic Simulation
by E. Rivière, E. Filippi, P. Dehombreux

Abstract - Prediction of the vibratory behaviour in machining is widely studied in the literature. The most common techniques of simulation consist in the linearization of the machining process; they lead to the traditional form known as of the «stability lobes». This approach does not take into account some characteristics of the milling process (periodic variation of chip thickness, entries and exits of the tool), especially in finishing. Dynamic simulation of the process, based on three fundamental pillars (modelling of the cutting forces, modelling of the machined surface and prediction of the relative movements between the part and the tool), are more suitable in this case.
The purpose of this article is to present a simulation tool that combines a mechanistic model of cutting forces with the generation of the machined surface using an “eraser of matter”approach. The computer program discretises the geometry in elementary discs along Z axis (model 2 D ½) and the dynamics is modelled using its modal characteristics. It predicts the cutting forces, the vibrations and the geometry of the machined surface. It is thus possible to give acceptable range for parameters such as spindle speed or depth of cut according to technological criteria (roughness after machining, maximum effort on the cutter or maximum vibration level).

Keywords: Chatter vibration, dynamic simulation, regenerative effect, surface modelling.

Modelling of the Wear of Some Tooling Materials
by A. Hebbar, D. Kaïdameur, D. Ouinas

Abstract - This experimental work consists in modelling the phenomenon of wear of various materials under the influence of the most imposing factors on wear like speed, the load applied, the viscosity of the lubricant and the nature of materials of the parts in contact. To answer that, it was necessary to produce a tribometer making it possible to carry out the various tests. To carry out our experiments, one chose an experimental design of the type 3^3-1.2¹. The parameters considered were: the hardness of the three types of materials to knowing the 16MnCr5, the 60WCrV7 and the X210Cr12, the speed of sliding motion on two levels and the viscosity of the lubricant on three levels. By the analysis of regression, one could obtain the mathematical model governing wear according to the influential parameters, like his surfaces of answer allowing to determine the optima thus to predict the behaviours of other materials having a hardness included in the studied field.

Keywords: Wear, Planning experiments, Regression, Optimization.

Numerical Investigations on the Melted Bath Movements During Deep Penetration Laser Welding
by E. H. Amara

Abstract - By applying a high power laser beam on metallic surfaces for welding purpose, liquid and vapour flows induced by fusion and vaporization of the material, are governed by the mechanisms of deep penetration welding. The comprehension of the phenomena leading to the metallic liquid movements occurring in the melted bath is important for the control of welding product. In this paper, modeling investigations are carried out to explain and to simulate the melted bath dynamics by a combined 2D and 3D numerical study. Finite volumes method allows numerical solution of the governing differential equations describing the compressible vapour, while a multiphase model is used to deal with the liquid-gas interfaces interaction. The obtained results describe the movements of the liquid region in the presence of the environing air and the vapour generated inside the cavity ‘keyhole’ produced by the laser beam.

Keywords: Deep penetration, laser welding, Melt pool, keyhole, melted bath movements.

Evaluation of the Stress Intensity Factor in a Structure Repaired with an Elliptical Composite Patch
by D. Ouinas, A. Hebbar, J. Viña

Abstract - The process of repairing structures by composite materials having various advantages. This method has received much attention from researchers and engineers. In this study, the finite element method is used to analyze the behaviour of a central crack repaired by bonded boron/epoxy composite patch by computing the stress intensity factor at the crack tip. The effects of mechanical and geometrical properties on the behaviour of the structure are highlighted. The results show that the stress intensity factor at the crack tip repaired by an elliptical patch is reduced to 5 % with regard to the repaired by a circular patch. The reduction obtained by using a boron/epoxy of fibers perpendicular to the crack is more important compared to the same patch having its fibers parallel to the repaired crack. The adhesive properties must be optimised to increase the performance of the patch repair or reinforcement.

Keywords: Elliptical patch, Bonded repair, Cracks patching, Stress concentration factor (CSF), Stress intensity factor (SIF), Finite element analysis.

Determination of Glass Mechanical Characteristics by Instrumented Indentation
by A. Chorfa, M. Hamidouche, M. A. Madjoubi, F. Petit

Abstract - In this work, we studied the mechanical characteristics of two different glasses (soda-lime glass and borosilicate) by using Vickers indentation. Considering the importance of the instrumented indentation and its increasingly widespread use, a systematic parametric study was thus undertaken. This study aims to determine the influence of the test conditions on the measured properties (the hardness, the elastic modulus and the fracture toughness). Complementary characterizations of the fracture toughness and the Young modulus by other conventional methods were also made for comparison. For each glass, we varied the indentation peak load as follows (10 N, 5 N, 3 N) and the dwelling time at these loads (8 s, 16 s, 30 s). The loading and unloading rate was fixed at 2000 mN/min. For each test condition, the load-penetration curves were obtained. We found that the parameters of indentation influence slightly the hardness, the elastic modulus and the fracture toughness.

Keywords: hardness, micro indentation, indentation, glasses, Toughness.

Simulation of the Effect of the Paddle Agitator Height on the Hydrodynamic Behaviour in an Agitated Vessel
by M. Bouzit, L. Benali, M. Hachemi

Abstract - The present investigation deals with the determination of the hydrodynamic behaviour induced by a paddle agitator and two-blade impeller in stirred vessel with different blade heights operating in laminar regime. Computational Fluid Dynamics (CFD) modelling of agitated system has been carried out using the code CFX. The velocity component calculation was carried out for paddle agitator in the bulk regions of the tank compare well with experimental observations and data. Many works confirmed that this type of geometry generates essentially, a tangential flow. The effects of the agitator height are examined, when this height decreases the paddle agitator becomes like a turbine and generates more important axial and radial velocities which are at the origin of secondary flows on both sides of the blade, the velocity component calculation for this type of agitator confirmed that a maximum axial and radial velocity for the lowest height agitator.

Keywords: Laminar mixing, 3D modelling, Newtonian fluid, stirred vessel.

First and Second Order Turbulence Closure for Bubbly Flows
by J. Chahed, G. Bellakhel

Abstract - The paper presents a tow-fluid model for turbulent bubbly flows based on first and second order closure of the turbulence. In the second order turbulence closure, the Reynolds stress tensor of the liquid is split into two parts: a turbulent part produced by the gradient of mean velocity and a pseudo-turbulent part induced by bubbles displacements. Each part is computed using a specific transport equation. The reduction of this second order turbulence closure leads to an original turbulent viscosity formulation. Based on this turbulent viscosity a three equation turbulence model (k,k_s,) is proposed. This model is applied to the computation of a turbulent bubbly wake and the numerical results clearly show that the three-equation turbulence model is able to represent the alteration of the turbulence structure of the liquid phase in bubbly flows due to the bubbles agitation.

Keywords: Two-phase flow, Bubbly flow, Two-fluid model, Turbulence model, Turbulent viscosity.

Prediction of CO₂ in the Exhaust of C.I. Engine Using Emission Model
by A. A. Pawar, R. R. Kulkarni, J. B. Sankpal

Abstract - This paper describes the emission factors for CO₂ which are rarely measured, typically they are calculated based on brake-specific fuel consumption (BSFC) and hydrocarbon (HC). This type of model does not require a CO₂ emission factors input file. This model can be used for biodiesel fueled compression engine as well as diesel fueled compression ignition engine. This comprehensive model directly gives the carbon dioxide in the exhaust without actual measurement quite accurately. In this paper the actual experimentation was carried using no. 2 diesel and compared with biodiesel fueled diesel engine which was carried out under similar operating conditions.

Keywords: Brake-specific fuel consumption, CO₂ model, Hydrocarbon, Thermal efficiency.

International Review of Mechanical Engineering - January 2007 - Papers

Performance Improvement of Adsorption Desalination Plant: Experimental Investigation

Please send any questions about this web site to info@praiseworthyprize.com

- Copyright © 2005-2010 Praise Worthy Prize -