Liste des publications
Plastic Deformation Effect on Wear and Corrosion resistance of Super Martensitic Stainless Steel
The microstructure and the mechanical properties of a super martensitic stainless steel (SMSS) were investigated in this study. Test specimens were taken from seamless tube generally used in oil and gas industries. The specimens were plasti- cally deformed by tension from its as-received state to different levels of elongation at 2%, 10%, and 15%, respectively. The focus was to study the influence of plastic deformation on the tribological behavior against alumina balls in dry conditions and the corrosion resistance in 3.5% NaCl solution. Analysis results showed an abrasive wear as the main wear mechanism. Plastic deformation prior to sliding wear test increases wear resistance as the deformation rate increases. Based on the elec- trochemical experiments, all of the specimens showed an increase in their corrosion resistance i.e., the corrosion potential Ecorr (vs. Ag/AgCl) tends to move toward more noble values with respect to the initial potential. The greatest polarization resistance was displayed by the specimen with 10% of deformation rate. Voir les détails
Mots clés : Super Martensitic Stainless Steel, Cold deformation, wear, corrosion
Arc Welding Current Control Using Thyristor Based Three-Phase Rectifiers Applied to Gas Metal Arc Welding Connected to Grid Network
The purpose of the welding operation is to ensure the continuity of the materials to be assembled in large industrial sectors. This study aims to suggest a topology of the Thyristor based three-phase rectifiers applied to the Gas Metal Arc Welding (GMAW) process connected to the grid network, the output currents are controlled and using various pulsed forms such as square, annealing, and spike pulse operations and investigate and compare between the effects of the three references welding currents structures on the welding current, welding voltage, droplet diameter, and welding quality. To have the best pulse operation, the amplitude and frequency are kept the same for all operations, the application of meshing graphs in the references of welding currents structures, welding current, welding voltage, and droplet diameter can illustrate a clear comparison between them. The simulation results show that the square pulse operation is the best among them. The Single-Sided Amplitude Spectrum (SSAS) method is also applied to the welding current and droplet diameter of the three operations under slow and rapid droplet detachment rates to estimate the droplet detachment frequency. The results show the great success of the SSAS in estimating the precise frequency. Voir les détails
Mots clés : Gas Metal Arc Welding, three-phase rectifier, grid network, SSAS method, welding current, welding voltage, droplet diameter, detachment frequency
DNS using CLSVOF method of single micro-bubblebreakup and dynamics in ?ow focusing
Numerical simulations are performed to investigate the breakup of air bubble in ?ow focusingcon?guration; the CLSVOF (coupled level set with volume of ?uid) method is employed to track theinterface, which allows a better identi?cation of the liquid–gas interface via a function called level set. TheCFD simulations showed that the velocity ratio, the interfacial tension, the outer channel diameter, thecontinuous phase viscosity, the ori?ce width and length play an important role in the determination of the airbubble’s size and shape. However, at low capillary number, increasing the ?ow velocity ratio gives a smallerbubble size in shorter time, while the increase in interfacial tension leads to a bigger bubble. Moreover, thecarrier ?uid is found to slightly affect the bubbling mechanism, while the smallest bubbles were obtainedwith the smallest ori?ce size. In addition, three breakup regimes are observed in this device: disc-bubble(DB), elongated bubble (EB) and the slug bubble (SB) regime ?ows. This work also demonstrates that theCLSVOF is an effective method to simulate the bubbles breakup in ?ow focusing geometry. In addition, acomparison of our computational simulations with available experimental results reveals reasonably goodagreement. Voir les détails
Mots clés : Bubbling, Multiphase ?ow, CLSVOF, CFD and ?ow focusing
Effects of Boundary Conditions and Operating Parameters on Temperature Distribution during the Friction Stir Welding Process
This work deals with a numerical simulation of the friction stir welding FSW process of alloy material AA2195-T8. A 3D transient thermal model for simulating the heat transfer phenomena in the welding phase is applied. In this model, the FSW tool is considered as a circular heat source moving in a rectangular plate having a cooling surface and subjected to nonuniformandnon-homogeneousboundaryconditions.ThethermalproblemissolvedusingthefiniteelementmethodaspartofaLagrangianformulation.TheobtainedresultsallowustodeterminethemaximumvalueofthetemperatureintheNuggetzoneoftheweldedjoint.Duringthisprocess,thethermalcycleandthetemperaturedistributionweredeterminedfordifferentvaluesoftheweldingprocessparameters.Theobtainednumericalresultsareingoodagreementwiththeoneavailableintheliterature. Voir les détails
Mots clés : Frictio n Stir Welding, Heat transfer, AA2195-T8
Thermal analysis of the friction stir welding process based on boundary conditions and operating parameters
Modelling of friction stir welding (FSW) remains a complicated task, as it is crucial to predict the mechanical properties of the final welded part. This research focuses on the numerical simulation aspect of the alloy material AA2195-T8. 3D transient thermal model was applied to simulate the heat transfer phenomena in the welding phase. In this model, the FSW tool is considered as a circular heat source moving in a rectangular plate having a cooling surface and subjected to non-uniform and non-homogeneous boundary conditions. To solve the thermal problem, the finite element method was used as part of a Lagrangian formulation. The obtained results allow us to determine the maximum value of the temperature in the Nugget zone of the welded joint. Sensitivity analysis of the operating parameters was also investigated to determine the thermal cycle and the temperature distribution during this welding process. Our results were successfully compared with the ones available in the literature with good agreement. Voir les détails
Mots clés : Friction Stir Welding, Heat transfer, AA2195-T8, alloy material, parameter characterisation
Chemical sensor array modeling. Quartz crystal microbalance sensors.
The primary objective of the paper is to develop Gibbs- Duhem like equations for the interactions between Quartz Crystal Microbalance (QCM) based sensor array and a mixture of vapors. These differential equations connect the variations of the sensors partial sensitivities or the sensors response with the gas mixture components concentrations. Furthermore, Thermodynamic models in the case of conducting polymer sensors, whose multi-component adsorption follows the generalized adsorption model of Langmuir have been deduced, these are differential equations that connect the adsorption entropies to the selectivities of the sensors and coefficients of standardization at constant temperature Voir les détails
Mots clés : chemical sensor array, Quartz Crystal Microbalance sensors, gas mixture, modeling, equations of Gibbs-Duhem, adsorption entropy
Fractional-Fuzzy PID Control Approach ofPhotovoltaic-Wire Feeder System (PV-WFS):Simulation and HIL-Based ExperimentalInvestigation
The utilization of solar photovoltaic (PV) generator as a power source for wire feedersystems (WFSs) of arc welding machines is one of the promising domains in solar PV applications. Thisarticle proposes a new type of welding WFS and investigates the PV penetrated energy systems. Theproposed system comprises of a solar PV generator, a DC/DC buck converter, and a permanent magnet DC(PMDC) motor. The power of the proposed standalone solar photovoltaic-wire feeder system (PV-WFS)can be widely improved using an intelligent fractional-order fuzzy proportional integral derivative (FOFuzzy-PID) regulator based on perturbing and observe (P&O) MPPT method. In this article, a FO-FuzzyPID regulator is also designed for a PMDC motor driven welding WFS system. Which will then control thewire feed rate of the welding WFS system. Furthermore, the dynamic reaction of the proposed solar PVWFS depends on the coefficients of these FO-Fuzzy-PID regulators, which are adjusted by a meta-heuristictuning algorithm based on particle swarm optimization (PSO) technique. The proposed strategy is testedusing MATLAB simulations and experimentally verified in real-time on a Hardware-in-the-loop (HIL)testing platform using a dSPACE®1104 board-based laboratory setup. Simulation and experimental resultsare acceptable and demonstrate the effectiveness, precision, stability, and dynamic reaction of the suggestedoptimized wire feeder regulating system and the considered intelligent P&O MPPT technique. Voir les détails
Mots clés : Buck converter, fractional-order fuzzy PID regulator, MPPT technique, PSO algorithm, PV module, wire feeder system (WFS).
An Enhanced MPPT Method CombiningFractional-Order and Fuzzy Logic PIDController for a Photovoltaic-Wire FeederSystem (PV-WFS)
The use of photovoltaic (PV) module as a power source for wirefeeder systems (WFSs) of arc welding machines is one of the promisingdomains in the solar PV applications. This paper provides a new kind of weldingWFS and investigates the PV penetrated power systems. The considered systemconsists of a PV module, a DC-DC buck converter, and PMDC motor. Thepower of the PV-WFS can be widely enhanced by using a Fractional-orderFuzzy PID (FO-Fuzzy-PID) controller based P&O MPPT algorithm. In thiswork, a FO-Fuzzy-PID controller is also proposed for PMDC motor drivenWFS. This will lead consequently to optimize the mechanical motor speed of theWFS. The dynamic response of the PV-WFS relies upon the parameters of theseFO-Fuzzy-PID controllers, which are optimized by using Particle SwarmOptimization (PSO) algorithm. Simulation results found are satisfactory andprove the stability, accuracy and dynamic response of the synthesized optimizedwire feeder regulating system and the proposed intelligent MPPT algorithm. Voir les détails
Mots clés : Solar photovoltaic (PV) module, Wire feeder system (WFS), Arc welding machines, DC-DC buck converter, MPPT control, FO-Fuzzy PID controller, Particle Swarm Optimization (PSO) algorithm
Sensorless Control of DC-DC Converter Using Integral State Feedback Controller and Luenberger Observer
This paper presents a design of linear state feedback control of DC-DC Boost converters, in order to achieve a particular desired behavior. To guarantee a zero steady state error, we introduce an integral action, which will work out this problem by assuring that the steady state error will end up to zero. If it is supposed that both the voltage and current are measured, so much more sensors are needed then and consequently causing a high cost, so that to estimate the voltage and current with a low cost and less complexity it is preferred to introduce a state observer. An observer or estimator is a dynamic system that uses the available information on a real system, according to the inputs and outputs of the real process and estimate the system state. Simulations results demonstrate the robustness and effectiveness of the proposed control scheme. Voir les détails
Mots clés : Boost converter, observer, Static error, Feedback control
State Feedback Control of DC-DC Converter Using LQR Integral Controller and Kalman Filter Observer
In this paper, the linear state feedback control using LQR controller for a DC/DC converter in the case of negative voltages topology is presented in order to achieve a particular desired behavior. To guarantee a zero steady-state error, we introduce an integral action, which will work out this problem by assuring that the steady-state error will end up to zero. For filtering and state estimation with a low cost and less complexity a state observer is obtained based a Kalman Filter observer. Detailed simulation study is presented to demonstrating the robustness and effectiveness of the proposed control scheme. Voir les détails
Mots clés : Linear quadratic regulator, DC/DC Buck-Boost Converter, Kalman filter, Static error