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International Review of Mechanical Engineering - July 2008 - Papers

An Explicit Beam Element Based on Periodic Bending Modes
Behaviour of Reinforced Concrete Beams Reinforced by Composite Materials
Finite Element Modeling of Fatigue Crack Propagation Using a Self Adaptive Mesh Strategy
Stress Intensity Factor Evaluation for Crack Emanating from Circular-Hole Using Finite Element Method
Constant Cyclic Loading Fatigue Crack Growth Modelling
Prediction of the Reliability of a Clutch in Function of the Wearing out of the Linings of the Clutch Disk
Acoustic Liners Behavior Investigation Using the Multimodal Scattering Matrix
Contribution to the Improvement of a Composite Insulator of Vibrations
Development of a Calibration Algorithm for Parallel Robots
Improvement in Hydrodynamic Torque Converter Design Process
Numerical Study of Transonic Flows Using Various Turbulence Models
Turbocharger Centrifugal Compressor Off-Design Performances Improvement by Inlet Prewhirl
A Practical Approach to Tolerance Allocation
LBM Mesoscale Modeling of Porous Media
Experimental Characterization of Mild Steel in Deep Drawing
Identification of Bi-Materials Mechanical Characteristics Using the Virtual Fields Method
Strain and Stress Analysis of Vacuum Chamber
Effect of Abrasive Wear on Drilling Tools
A Differential-Algebraic Approach for Dynamic Modeling of Diesel Engine Particulate Aftertreatment Systems
Pareto Optimization of GMDH-type Neural Networks for Modelling and Prediction of Hoop Strain in Explosive Forming Process

International Review of Mechanical Engineering - Papers

An Explicit Beam Element Based on Periodic Bending Modes
by L. T. Tenek

Abstract - The present article presents a new three-dimensional beam finite element, the element EB8, based on the Explicit FEM To the element is assigned a set of modes. For bending, periodic modes are used in the form of sines and cosines. A diagonal Modal elemental stiffness matrix is formed which through a series of matrix transformations relates to the local and global coordinate systems. An initial load due to temperature is derived, as well as the elemental modal and global mass and geometric matrices. All quantities are explicitly defined. The element is computationally implemented and is used to study a number of beam, arc, and frame structures.

Keywords: Explicit FEM, beam element, modes, modal matrices, periodic bending modes, computing.

Behaviour of Reinforced Concrete Beams Reinforced by Composite Materials
by M. Rafik, G. Mohamed, N. M. Salah

Abstract - The reinforcement of the reinforced concrete structures is one of the curative methods used for the rehabilitation of the structures in order to ensure its service and long life period. Various techniques of reinforcement appeared. The first to be used is the joining of steel elements on the surfaces exposed to the stresses due to the loading forces. With the appearance of fibre reinforced polymers (FRP), and in order to avoid the problems involved in the use of steel (corrosion, weight, etc.), the elements of reinforcement are increasingly manufactured with this new type of material. However, these structures present new scientific problems and in particular the mode of failure. The aim of this article is the theoretical and numerical study of the behaviour to failure under three points (coupling bending-shearing) of a reinforced concrete beam reinforced and repaired using carbon fibre plates in order to find a methodology of dimensioning by taking in account the effect of the behaviour of various materials: reinforced concrete, adhesive and composite materials. The results found show that the joining of composite materials on reinforced concrete structures gives an increase in the ultimate load and a reduction in the deformations in the concrete and steels.

Keywords: carbon fibre, composite materials, reinforcement, repairs, three points bending.

Finite Element Modeling of Fatigue Crack Propagation Using a Self Adaptive Mesh Strategy

by A. M. Alshoaibi, A. K. Ariffin

Abstract - A new finite element model has been developed to predict fatigue crack growth in arbitrary 2D geometries under constant amplitude loading. The purpose of this model is on the determination of 2D crack paths and surfaces as well as on the evaluation of components Lifetimes as a part of the damage tolerant assessment. Throughout the simulation of crack propagation an automatic adaptive mesh is carried out in the vicinity of the crack front nodes and in the elements which represent the higher stresses distribution. The fatigue crack direction and the corresponding stress-intensity factors are estimated at each small crack increment by employing the displacement correlation technique under facilitation of singular crack tip elements. The propagation is modeled by successive linear extensions, which are determined by the stress intensity factors under linear elastic fracture mechanics (LEFM) assumption. The stress intensity factors range history has to be recorded along the small crack increments. Upon completion of the stress intensity factors range history recording, fatigue crack propagation life of the examined specimen is predicted. Verification of the predicted fatigue life is validated with relevant experimental data and numerical results obtained by other researchers. The comparisons show that this model is capable of demonstrating the fatigue life prediction results as well as the fatigue crack path satisfactorily.
Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved

Keywords: Finite element simulation, stress intensity factors, mixed mode fracture, adaptive mesh, Fatigue life prediction.

Stress Intensity Factor Evaluation for Crack Emanating from Circular-Hole Using Finite Element Method

by M. Souiyah, A. Alshoaibi, A. Muchtar, A. K. Ariffin

Abstract - Finite Element Analysis (FEA) combining with the concepts of Linear Elastic Fracture Mechanics (LEFM) provides a practical and convenient means to study the fracture and crack growth of the materials. 2-D finite element model is developed for two different geometries; a rectangular plate with cracks emanating from a circular hole and Double Edge Notched Plate (DENT). Both geometries are in tensile loading and under mode I conditions. In this paper, a displacement extrapolation technique is employed particularly, to predict the crack propagations directions and to, calculate the Stress Intensity Factors (SIFs). Therefore, verification of the predicted SIF and crack trajectory are validated, with the relevant numerical and analytical results obtained by other researchers.

Keywords: linear elastic fracture mechanics, adaptive refinement, stress intensity factors.

Constant Cyclic Loading Fatigue Crack Growth Modelling

by A. Ali, T. I. Mohd. Ghazi, M. Z. Mohammadi

Abstract - A critical review concerning fatigue crack growth rate [FCGR] modelling is presented in this paper. The paper give a detailed of previous attempts have been made to model the FCGR from the simplest empirical model by Paris to advance and contemporary models such as the Weertman strain energy model, Tomkins high strain model, Coffin and Manson plastic strain model, Hobson-Brown model and Navarro- E de Los Rios, N-R models. The pros and cons of each model are also discussed in term of capability of the model to incorporate the effects of a microstructure, hardening, residual stress, mean stress effects and surface roughness of the materials.

Keywords: Fatigue crack growth modelling, Constant loading.

Prediction of the Reliability of a Clutch in Function of the Wearing out of the Linings of the Clutch Disk
by J. Angulo Z., R. Mora M., G. Filippone, C. Castellote

Abstract - The present article proposes a practical methodology to find the reliability of a clutch, very useful for engineers of design, manufacturers and engineers of after sale. The methodology is based on an experimental procedure based on testing life.

Keywords: Reliability, Clutchs, Testing life.

Acoustic Liners Behavior Investigation Using the Multimodal Scattering Matrix

by M. Taktak, J. M. Ville, M. Haddar, G. Gabard, F. Foucart

Abstract - In this paper, the acoustic behavior of Helmholtz’s resonator type liner used in aeronautics applications is presented. The aim of this work is to study how the liner properties can be modified by the mounting conditions on the wall of a cylindrical duct element. To achieve this objective the measured multi-port scattering matrix, power acoustic dissipations are compared with results performed by FEM assuming axi-symmetry and a uniform and locally reacting material which impedance is measured or resulting from a model. Results show that in plane wave conditions the agreement between experiment and theory is satisfying but that a large discrepancy occurs when higher order mode is incident on the liner element pointing out a modification of the acoustic properties of the lined wall.

Keywords: Locally reacting liner, scattering matrix, Acoustic power dissipation.

Contribution to the Improvement of a Composite Insulator of Vibrations

by R. Nasri, H. Kharroubi, Y. Abdelli

Abstract - In order to achieve a maximum decrease in the transmissions of the machines vibrations toward their foundation and inversely from the foundation to the machines frame, several designers have the tendency to use stratified, viscous-elastic and elastic materials. Stratified materials are used by alternation with viscous and elastic materials and have the advantages of viscous and interface absorption of vibrations. In this work, for a better insulation of machines-foundation vibrations, an optimal solution of stacking materials layers was provided for a given machine characteristics. In order to compare the results and to optimize the choice of the insulator, the machine was modelled by a one DOF system while keeping the only dominant movement of the machine, followed by a discreet modelling of the passive insulator (from one to several DOF). The interface influence is not considered. The analysis of the results of the optimization and the influence of the increase of the DOF of the insulation system on the whole vibratory behaviour (machine and insulation system) allowed several practical conclusions on the stacking of the composite, the number of layers and the characteristics of layers components.

Keywords: Optimisation, isolators, composite materials, dof, transmissibility.

Development of a Calibration Algorithm for Parallel Robots
by C. Brisan, A. Capustiac

Abstract - Parallel mechanisms usually have a better repeatability compared to the serial mechanisms, but they don’t necessarily have a better accuracy in positioning, due to the limitations caused by assembly errors. The calibration of a robot is the process of identifying the real geometrical parameters from its structure. This paper presents a calibration algorithm for the Partner robot with 6 DOF, based on a wire tracking system. This wire robot was designed as a parallel manipulator with 3-2-1 configuration. Forward kinematics was used for calculating the position and the environment Matlab/Simulink was used for simulating the calibration process.

Keywords: Calibration, Parallel Robots, Virtual model.

Improvement in Hydrodynamic Torque Converter Design Process
by A. Kesy, Z. Kesy, M. R. Jackson, R. M. Parkin

Abstract - This paper describes the design process of hydrodynamic torque converter components for modern transmission systems. The design process was divided into two steps: virtual design process i.e. numerical calculation and geometric model creation and physical realization i.e. prototype of components fabrication and testing. For creation of the impeller prototypes laser sintering technology was applied. Verification of this new technology was carried out by experiment. The prototype of hydrodynamic torque converter with a stator made with new technology was tested on a typical test rig. Based on analyze of the fabrication and assembly processes and the test results issues which appear during the stator design process were identified and considered.

Keywords: Hydrodynamic torque converter, laser sintering technology, transmission system.

Numerical Study of Transonic Flows Using Various Turbulence Models
by N. Bekka, R. Bessaïh, M. Sellam

Abstract - In this paper, validation and assessment of various turbulence models are performed in transonic flows, including an algebraic Baldwin Lomax model, Spalart Allmaras one equation, and two equation (k-ε, k-ω and SST k-ω) turbulence models. The NACA 0012 airfoil has been chosen for the turbulence model validation studies. The three test cases selected here included both attached and separated transonic flows. This study shows that the five turbulence models provide satisfactory results for transonic attached flows. However, all models, fail to predict the location of the shock correctly when a strong shock and a shock induced flows separation are present. Compared to other models, it has been shown that the SST k-ω model is the most robust model in the prediction of lift coefficient for all cases. Computed results are performed with the CFD-FASTRAN code by using the fully implicit scheme for time integration, and the upwind Roe flux difference splitting scheme for space discretization augmented by a high order Min-Mod limiter to damp spurious oscillations and to allow for sharp shock resolution.

Keywords: Numerical study ,Transonic flows, Turbulence models, Airfoil.

Turbocharger Centrifugal Compressor Off-Design Performances Improvement by Inlet Prewhirl
by A. Liazid, L. Izidi, M. Tazerout

Abstract - Radial turbochargers are commonly used in automotive diesel engines. The changing flow condition caused by the engine regime at the turbine entry requires good matching of the turbocharger in a wide range of engine operations. A solution has been found by using variable nozzle turbine. This paper studies the influence of the incidence flow direction at the inlet of the turbocharger wheels on the compressor performances. This study is developed in two steps. In the first step, the influence of the variable nozzle guide vane of the turbine stage on the operating compressor performances is examined. An experimental investigation was performed to achieve this purpose. In the second step, a prediction model for centrifugal compressor is developed and validated. This model is used to investigate the influence of a recent prewhirl design on the centrifugal compressor performances. The obtained results are presented and discussed.

Keywords: Centrifugal Compressor, Diesel Engine, Prewhirl, Turbocharger, Variable Nozzle Turbine.

A Practical Approach to Tolerance Allocation
by M. N. Islam

Abstract - This paper reviews the currently available tolerance allocation tools and identifies their shortcomings which are then used to create a better tool suitable for industrial applications. The obstacle in the application of existing tolerance allocation tools appears to be the lack of up-to-date cost data. In this paper, a tolerance allocation strategy that is simple and practical is presented. It is suitable for use in a Concurrent Engineering (CE) environment and incorporates some of the existing methods/tools viz. the method of guided iteration and decision matrix. It is interactive and utilizes the expertise of all the members of the CE team. The proposed strategy uses process capability tolerance as the basis of optimization, thus avoiding the need for cost-tolerance data.

Keywords: Concurrent Engineering, Decision Matrix, Method of Guided Iteration, Tolerance Allocation.

LBM Mesoscale Modeling of Porous Media
by A. Nabovati, A. C. M. Sousa

Abstract - Permeability is one of the most important bulk properties for the characterization of fluid flow in porous media. However, despite all the considerable body of research work over the past years using experimental, analytical, and numerical approaches, its determination is still a challenge. The methodologies, which have been used to measure, calculate and predict the permeability of different types of porous media, in general, tend to suffer from various levels of limitations in their applicability and, moreover, no general correlation for the permeability is available. Among the different predictive methods for the permeability, numerical pore level fluid flow analyses have been receiving increasing attention in recent years, due to its robustness and flexibility. In this approach, the viscous fluid flow is directly simulated in the pores of the porous medium with no further modeling required. A simple representation of the pore structure can be in the form of the ordered and random packings of spheres, cylinders or square obstacles. In the present paper, the main objective is to introduce the lattice Boltzmann method (LBM) as a powerful tool for the mesoscopic pore level fluid flow simulation in porous media; two and three dimensional case studies are presented to demonstrate the capabilities of the mesoscale modeling for porous media fluid flow problems using the LBM. To demonstrate an approximation to a reconstructed medium, the fluid flow simulation in a 2D random arrangement of square obstacles with different aspect ratios is presented. Results of the three dimensional simulations of the fluid flow in ordered and random packings of spheres are also reported; effect of the spheres’ radius and their arrangement on the permeability is also investigated. The results are in very good agreement with the available correlations.

Keywords: pore level analysis, permeability prediction, random sphere packing, LBM.

Experimental Characterization of Mild Steel in Deep Drawing
by O. Boussaid, N. Bourgeois, M. Martiny, G. Ferron, K.Chaoui

Abstract - The present study is based on cases of sheet rupture, which occurred on deep drawn components produced in a workshop of one company during deep drawing operations. A characterisation of material behaviour in deep drawing is proposed to define the limits imposed to the forming of sheets by the development of a zone of localised necking. First, tension tests are carried out to determine the characteristics of the material, i.e., the anisotropy coefficient and the hardening law. Then, deep drawing tests of the Marciniak type are carried out to determine the Forming Limit Curve (FLC) of the material by means of the method of image correlation using specific software. Knowing the properties of the material and the limits of deformation which define the occurrence of necking, the problem of sheet rupture during material forming will be reduced.

Keywords: Forming, deep drawing, necking, failure, FLC.

Identification of Bi-Materials Mechanical Characteristics Using the Virtual Fields Method
by Z. Zemouri, K. Chaoui, H. Hamadache

Abstract - One method of identifying parameters governing the behaviour of an elastic material covers the Virtual Fields Method (VFM). However, this method has been validated for only homogeneous materials. In the case of compound materials, the presence of strong gradients strains near the interface limits the potential of this method, which requires some adjustments. This work focuses on the validation of the VFM applied to a Bi-Material composed of Polymer and Epoxy. The results obtained are in correlation with the characteristics of components used.

Keywords: Interface, Laws of Behaviour, Material non-homogeneous, Virtual fields method.

Strain and Stress Analysis of Vacuum Chamber
by S. Boutabba, A. Chettah, A. Boukercha

Abstract - In this paper, a theoretical analysis of strain and stress fields of a vacuum chamber used to produce carbon nanoparticles from the combustion of gaseous blend is presented. The method of analysis for this study entails a 2D and 3D Finite Element Method (FEM) in which the stress and displacement are solved for a cylindrical chamber. The vacuum chamber has a cylindrical form with hemispherical ends. The goal of this study is the prevision of the chamber sizes from the knowledge of the pressures imposed on the inside and outside boundaries of the chamber as well as the elastic characteristics of the material.

Keywords: Finite element method, strain and stress, vacuum chamber.

Effect of Abrasive Wear on Drilling Tools
by A. Dalia, A. Hafsaoui

Abstract - This paper presents the experimental results of shore hardness index and cone indenter hardness and average grain size and continuous abrasive index on the impact abrasive index. A good correlation was found with combined parameters. These results can predict during life of drilling tools, and then avoid the breakdown.

Keywords: Wear, Abrasiveness, Drilling, Tools.

A Differential-Algebraic Approach for Dynamic Modeling of Diesel Engine Particulate Aftertreatment Systems
by F. Su, B. W. Gordon, H. Hong

Abstract - A new model for a typical diesel engine particulate aftertreatment system, which consists of exhaust pipes, a fuel burner for active soot regeneration and a diesel particulate filter (DPF) is developed. The model described by nonlinear high-index differential-algebraic equations (DAEs) is more general than ordinary differential approximations, and is realized using a singularly perturbed sliding manifold (SPSM) approach. The system parameters and model realization are verified using experimental data. Behaviors of the dynamic system (stability and observability) near an equilibrium point are investigated using Lyapunov’s linearization method. The DAE model is transformed into a linear-like form and based on that a sliding mode observer (SMO) is designed. Application of the SMO design approach to the aftertreatment system model is evaluated using actual vehicle test data and results are encouraging.

Keywords: Sliding Mode Observer, Differential-Algebraic Equation, Nonlinear System Modeling, Diesel Particulate Aftertreatment System, Diesel Engines.

Pareto Optimization of GMDH-type Neural Networks for Modelling and Prediction of Hoop Strain in Explosive Forming Process
by N. Nariman-Zadeh, E. Haghgoo, A. Jamali

Abstract - In this paper, Evolutionary Algorithms (EAs) are deployed for multi-objective Pareto optimal design of Group Method of Data Handling (GMDH)-type neural networks that have been used for modelling of the effect of dynamic yield stress, thickness, charge mass, centre deflection and distance from centre on the hoop strain in explosive forming process using some input-output experimental data. In this way, EAs with a new encoding scheme is firstly presented to evolutionary design of the generalized GMDH-type neural networks in which the connectivity configurations in such networks are not limited to adjacent layers. Multi-objective EAs (non–dominated sorting genetic algorithm, NSGA-II) with a new diversity preserving mechanism are secondly used for Pareto optimization of such GMDH-type neural networks. The important conflicting objectives of GMDH-type neural networks that are considered in this work are, namely, Training Error (TE), Prediction Error (PE) and number of neurons (N) of such neural network. Different pairs of these objective functions are selected for 2-objective optimization processes. Therefore, optimal Pareto fronts of such models are obtained in each case which exhibit the trade-offs between the corresponding pair of conflicting objectives and, thus, provide different non-dominated optimal choices of GMDH-type neural networks models for the explosive forming process. Moreover, all the three objectives are also considered in a 3-objective optimization process which consequently lead to some more non-dominated choices of GMDH-type models representing the trade-offs among the training error, prediction error, and number of neurons (complexity of network), simultaneously. The overlay graphs of these Pareto fronts also reveal that the 3-objective results include those of the 2-objective results and, thus, provide more optimal choices for the multi-objective design of GMDH-type neural networks in terms of minimum training error, minimum prediction error and minimum complexity.

Keywords: Explosive forming, Multi-objective optimization, Genetic algorithms, GMDH, Pareto.