Mohamed Haddar

• PhD
• Professor at National Engineering School of Sfax

This paper presents a formal approach to solving the strict time constraint problem in discrete event systems with disturbance inputs. This class of systems is represented by partially controllable timed event graphs, and some paths are subject to upper time bounds imposed on tokens during their traversal of these paths. An analytical method for de...

This study introduces the first comparative analysis of multiple machine learning models for predicting CBGA solder joint lifespan under thermal cycling, a key factor in electronic reliability. Expanding the dataset from 45 to 295 reveals that data augmentation significantly improves prediction accuracy. Basically, DS2 is well validated as it incor...

Thermal conductivity is a critical property of nanoparticle-enhanced phase change materials (NEPCMs), directly influencing their performance in thermal management applications. This study presents the development of an artificial neural network ANN model to accurately predict the thermal conductivity of NEPCMs, showcasing the potential of machine l...

The efficiency of crystalline silicon-based PV cells decreases with increase in operating temperature so this work studies the performance and effectiveness of PV cell cooling using PCM (paraffin wax). It is clear that the cooling with paraffin wax suffers from limitations, namely the melting point and the low thermal conductivity of the wax. The m...

Machine learning enhances machine diagnostics through advanced data analysis, pattern recognition, and fault prediction. This study investigates the application of machine learning algorithms for bearing fault detection. The objective is to develop intelligent methodologies for the predictive diagnosis of bearing faults in rotating machinery, empha...

This paper emphasizes the role of fuel substitution in mitigating vibrations and enhancing the performance and reliability of internal combustion engines (ICEs). Using MATLAB for modal analysis, the study investigates natural frequencies and identifies potential resonance issues within critical engine components. The primary focus is on analyzing a...

Modeling planetary gearboxes is an important field of research, since it helps in condition based monitoring of the system. Multiple models with different approaches were developed last decades. They showed interesting results, but they did not reflect all involved phenomena. Indeed, specifically in a complex rotating systems such as staged planeta...

Component obsolescence and shortages impact virtually all systems, particularly those with extended lifespans, such as aircrafts or trains. Obsolescence (i.e. state of being outdated) and shortage (i.e. lack of components) are distinct yet interconnected challenges and despite their inevitability, systems must maintain acceptable performance levels...

This paper introduces an active vibration suppression system for solar panels, addressing the detrimental effects of environmental vibrations. The system employs piezoelectric sensors to detect unwanted movements in real time and generate compensatory signals to counteract vibrations. An intelligent network of sensors and actuators dynamically adju...

This study investigates the effectiveness of Proportional-Integral-Derivative (PID) and Fractional Order PID (FOPID) controllers in suppressing vibrations within a cantilever beam system equipped with a piezoelectric actuator. Vibration suppression is essential in high-precision applications such as machining and aerospace, where stability and accu...

The fmincon optimisation technique is used in this study to optimise the active vibration control of a piezoelectric beam system. System matrices, natural frequencies and mode shapes are derived by modelling the dynamic behaviour of the beam integrated with piezoelectric patches. A feedback control approach is used to attenuate the vibrations and t...

This study examines a cantilever beam equipped with symmetrically placed piezoelectric sensors and actuators on its top and bottom surfaces. The beam's behavior is simulated in ANSYS and Matlab, incorporating a traditional control strategy. Control actions are implemented within the ANSYS finite element model through APDL scripting and Matlab integ...

To ensure durable performance and optimal function of electronic components, it is crucial to guarantee their reliability, robustness and goodness of fit. The solder joints used in the BGA (Ball Grid Array) component play an intrinsic role in the reliability of the system. The vibration present in BGA triggers fatigue in solder joints, which raises...

Unstable spindle rotation can result in vibrations, chatter, and increase in surface roughness, leading to productivity reduction and energy consumption rise. The combined effects of nonlinearity owing to different bearing types and spindle materials significantly impact the stability of the machine tool spindle system, which needs to be considered...

This paper presents a comprehensive study on the application of Artificial Intelligence (AI) methods, specifically machine learning and deep learning, for the diagnosis of bearing faults. The study explores both data preprocessing-dependent methods (Support Vector Machine, Nearest Neighbor, and Decision Tree) and a preprocessing-independent method...

Choosing the right disc geometry carefully is essential for enhancing brake disc thermo-mechanical performances. The present investigation examines the crucial effect of automotive brake disc designs on their thermal and aerodynamic performance utilizing computational fluid dynamics (CFD). A thorough investigation was carried out on four different...

This paper proposes a complete model for simulating and controlling particle distribution in the final part manufactured by the resin transfer molding (RTM) process. This model combines (i) a numerical model to simulate the injection of a particle-filled resin through the fibrous medium and (ii) the integration of the genetic optimization algorithm...

This paper describes a multi-objective reliability-based design optimization (MORBDO) of a two-stage wind turbine gearbox. The optimization process incorporates the gear's reliability of accounting for the uncertainty of its internal geometric parameters. It also ensures that constraints relating to the gear's reliability index and efficiency are r...

This work deals with the control problem of Discrete Event Systems (DESs) modelled by Timed Event Graphs (TEGs) and subject to Generalized Marking Constraints (GMCs). The aim of this paper is to propose an algebraic methodology for the determination of control laws in the form of state feedback, guaranteeing the satisfaction of marking specificatio...

As the demands and challenges of today's industries are continuously changing, for this reason, the industry is trying to revolutionize the way, and the technologies applied eventually. Optimizing the manufacturing process to achieve maximum production with minimum exploitation of resources is the main objective of Industry 4.0 by improving its per...

This research is driven by the overarching objective of assessing and characterizing the intricate damage mechanisms exhibited by glass/epoxy composite laminates, utilizing the acoustic emission methodology. The experimental approach involved the application of static stress to the test specimens, enabling the systematic tracking of various damage...

The present study aims at analyzing the free vibration behavior of hybrid fiber-reinforced laminated composites is a complex phenomenon that is influenced by a number of factors, including the type of fibers used, the volume fraction of the fibers, the stacking sequence of the plies, and the boundary conditions of the structure. This study investig...

Loosening of an assembly is a critical phenomenon, it can cause damage in the aeronautical field which uses a huge number of bolted joints. It should be studied correctly to avoid catastrophic phenomena. Most of studies focused on the loosening phenomenon resulting from transversal load or axial load. This paper is dedicated to the study of the inf...

This publication is based on research into the robustness of a complex system. Complexity can be explained by its multi-element structures and deals with the interaction of parameters and investigations. To study the robustness of a complex system, a 12-DDL two-stage spur gear transmission is established. Gearbox systems are characterized mainly by...

Acoustic coatings are the most widely used techniques for attenuating sound levels in duct systems. Porous materials are preferred because their performance is less frequency dependent. One of the methods used to describe the acoustic propagation and scattering in ducts containing these porous coatings is the scattering matrix method. The scatterin...

The study aims to analyze the porosity of Carbon Fiber Reinforced polymer samples produced by 3D printing, with a focus on the impact of printer settings. Specific printing parameters including printing speed, printing temperature and printing orientation are selected. The porosity is calculated as function of measured and theoretical masses and co...

The car gearbox is running under acyclism regime since it is excited by the variable load and speed generated by the Internal Combustion Engine (ICE). These excitations can be transmitted to the car driver through the gearbox. Most of the research works on its dynamic behavior considered a simple stage gearbox and four cylinders engine whereas the...

Car suspension dynamic behavior under uncertainty is a multidisciplinary field of study that aims to understand and predict a vehicle’s performance in various operating conditions, as well as a complex one since it is a system that interacts with its environment. The robustness of such systems requires a careful understanding of the system design p...

This paper is dedicated to solving the control issue of a class of discrete event systems with disturbances and subject to Mutual Exclusion Constraints. More precisely, a new analytical approach for designing control laws is suggested to guarantee the satisfaction of these constraints in Timed Event Graph Networks (NTEGs) with some uncontrollable i...

One of the primary types of dynamic loads is random vibration analysis. Composite sandwich materials used in dynamic structures are likely to be damaged due to high acceleration, stress levels, and deformation under dynamic loads. Therefore, it is essential to analyze these materials under dynamic load conditions. In this study, a composite sandwic...

In gear systems, current models mostly supposed gear mesh damping ratio was a constant. In real applications, gear mesh damping may not be constant for different tooth contact positions and is dependent on the gear damage. For that reason, the damage effect on mesh damping has been the subject of intensive research and may deserve some investigatio...

Printed circuit boards (PCBs) are essential modules which are incorporated in a wide range of industrial equipment in order to control or signal manipulation applications. Printed circuit boards are subjected to various types of loads, such as vibrations, shocks and static loads. This paper discusses the development and use of an analytical approac...

This present study proposed a study of a multiple-phase change materials-based heat sink. The model was composed of four PCM cavities separated by a 2 mm plate fin. Two heat values were adopted to define the effect of the heat flux over the performances of the single PCM-based heat sink and multiple PCM-based heat sink. Three PCMs: RT44, RT64, and...

Wind energy is an environmentally friendly option to ensure energy security during a period when fossil fuel reserves determine the long-term development of the economy. To improve wind turbines’ ability to produce electricity, blades are becoming larger and more flexible. This increasing flexibility and size of wind turbine blades leads to study t...

Dynamic models of transmission systems have long been used to study the behavior of vibration response and its impact on gear fault detection. This work proposes a method for detecting separated and simultaneous fractures caused by a variation in gear mesh stiffness (GMS) for a dynamic model of a spiral bevel gear system (SBGS) using statistical pr...

This study investigates the detection of crack faults in bevel gears with a new method based on univariate statistical control charts (USCCs). The focus was on determining four types of operating states for the gears: healthy operation, faulty operation with a crack length of 0.25 mm, a crack length of 0.5 mm, and a crack length of 0.75 mm. Laborat...

Given the tremendous growth of the microelectronics industry in recent years, soldering efficiency is more crucial than ever. Despite the great importance of the solder joints, these interconnections happen to be the weakest link in electronic packaging. Many surveys have been carried out in order to investigate their thermomechanical reliability b...

This study investigated the influence of temperature variations on the mechanical and dynamic behaviors of biobased composites incorporating a passive control layer. These composites, which include an external layer made up of Flax/polylactic acid (PLA) and an internal layer of rubber, were manufactured using 3D printing technique. To better unders...

The friction occurring between the teeth of gears is a significant contributor to energy loss in gear drives. Factors like the load, speed, and coefficient of friction (µ) play a crucial role in determining the extent of frictional losses in gears. The coefficient of friction (µ) is a complex function influenced by various tribological parameters,...

Photovoltaic (PV) technology is one of many renewable energy sources, which converts solar energy directly received into electricity. In recent years, PV has advanced quickly as researchers try to make it more effective. 80% of the solar radiation that hits PV cells is absorbed, but only 12–18% of that energy is converted into electricity, with a m...

Modern life is marked with the extensive use of machine tools. The latter stand for high consumers of electrical energy which increase carbon emissions. For this reason, various solutions aiming to reduce energy consumption in industrial sector are elaborated. One solution lies in the use of economical materials for the spindle rotation system supp...

In this study, the 3D printing technology was adopted to produce carbon fiber-reinforced polylactic acid and polyethylene terephthalate glycol composites. Fused deposition modeling process was conducted at different settings of printing parameters, specifically, raster angle, printing speed, and extrusion temperature. Each of the selected printing...

The use of biocomposite materials in different fields requires enhanced knowledge of the nonlinear phenomena related to their complex mechanical behaviour. Namely, nonelastic mechanisms such as damage, plasticity, and rupture, potentially coupled with viscosity incidence, affect the structure’s lifetime. In this context, the aim of this paper is to...

Water absorption and vibration issues are major concerns for manufacturers and researchers using bio-based composites. In light of this, this work examines how water aging affects the dynamic characteristics of a sandwich with a reentrant auxetic core. The material considered to manufacture the specimens is polylactic acid (PLA) reinforced with fla...

In the automotive field, advances in control tools have considerably improved performance in terms of both comfort and security. These developments depend on behavioral models of the mechanical groupings that make up the vehicle, created using approaches based on multi-body dynamics and more or less complex models that occasionally present very mar...

In swarm robotics, robots solve problems using collective behaviors similar to those observed in natural systems, such as birds, bees or fish. They determine their collective behavior through several simple interactions. However, the behavior of swarms emerging from local interactions remains difficult to predict. When trying to design swarm roboti...

The automation of machinery monitoring in various industries has been revolutionized by this meticulously designed framework, which significantly reduces the need for manual oversight and interpretation. Through the analysis of simulated vibration signals, a new data-driven framework for monitoring gearbox condition is introduced , which utilizes s...

Particle impact dampers are dissipative devices that can easily be coupled to structures in order to reduce vibrations over a wide frequency range and in adverse environmental conditions. In this work, a multiple-sphere chain impact damper is coupled to a cantilever beam in order to attenuate its flexural motions. This simple configuration was chos...

This research examines a Progressive Damage Model for laminated composites using a wave-based technique. Using conventional numerical methodologies, such studies may require a significant amount of CPU time. Compared to standard techniques, the approach proposed can provide a quick and cost-effective evaluation. This work presents a numerical appro...

The objective of a theoretical simulation of an experiment is the identification of the experience parameters which are the most sensitive to errors to take them into account during the measurement and to reduce their corresponding errors. In this study, a simulation of the experiment procedure of measurement of the scattering matrix and the acoust...

This work focuses on Wire Arc Additive Manufacturing (WAAM) technology using the Tungsten Inert Gas (TIG) welding method with aluminum 5083 as the substrate and aluminum 5356 as the filler material. This method uses a layer-by-layer approach to build the part. A design of experiment (DOE) was carried out with three independent variables, namely (i)...

Gearbox monitoring is considered an important scientific focus for predicting preventative maintenance plans. In these systems, mechanical defects such as loading problems, eccentricity and torsional vibrations lead to shaft fatigue and other damage to various other mechanical components. Various methods have been developed to detect and identify t...

Abstract Interest in rotary systems whose performance and efficiency are influenced by their weight as well as guidance type has continued to grow over the last decades. Actually, the dynamic analysis of composite shafts supported by active magnetic bearings (AMBs) seems to be neglected by researchers despite its effect on rotating system efficienc...

The success or failure of a drone mission depend on several elements, including the drone’s mass and payload, the surrounding environment, the battery’s state, and the propulsion system’s performance. Several studies have been undertaken addressing the propeller performance of this final component, particularly for fixed-wing or quad copter drones...

Understanding the phenomena that can occur in a given medium necessitates a clear grasp of its chemical composition. In this context, various techniques including infrared (IR) spectroscopy were developed. In this work, we determined the bond force constants of CO2 molecule in gas phase state and trapped in a nanocage by applying group theory to th...

The detection and location of pipeline leakage can be deduced from the time arrival leak signals measured by acoustic sensors placed at the pipe. Ongoing research in this field is primarily focused on refining techniques for accurately estimating the time delays. This enhancement predominantly revolves around the application of advanced signal proc...

Phase change materials represent efficient performances in the thermal management field. However, the low thermal conductivity poses a serious restraint for electronic cooling applications. Recently, the use of multiple phase change materials and the dispersion of nanoparticles are the most recommended techniques to improve the performance of the h...

In this paper, an experimental procedure is aborted in order to fight against noise and reduce noise pollution through the synthesis of an ecological material with acoustic potential made from industrial waste. In fact, phosphate sludge is a sound absorber and it is really possible to exploit the tons of this material discarded in the wilderness wi...

Users of electronic devices expect efficiency, affordability, and long service life. From this perspective, the optimization of their performance while reducing costs is paramount. The objective of this paper is to find the best compromise between minimizing the volume and thus cost, and preserving the efficiency of the component. This work is base...

The dynamic behavior of an active magnetic bearing (AMB) mounted rotor was investigated through an analytical study conducted as part of this research work. A biased AMB model was developed, in which six electromagnets were supplied with a bias current I0, and their respective control currents. The magnetic load was obtained through a differentiate...

Etude statique d'un bio-composite anti-trichiral réalisé par la fabrication additive Static study of an anti-trichiral bio-composite made by the additive manufacturing Abstract In several industrial sectors, there are continuous requirements to develop lighter materials for various loading situations. The common process of reaching this is mostly t...

Les biocomposites sont des matériaux qui combinent un renfort en fibres naturelles avec une matrice en polymère synthétique. Ils offrent un certain nombre d'avantages par rapport aux composites synthétiques traditionnels, tels que la légèreté, la solidité et la durabilité. Cependant, les biocomposites sont également plus sensibles aux dommages caus...

Cracks are described as sharp and diffusive surfaces in failure mechanical models. In this paper, a finite element model is developed by using a diffusive description of crack discontinuities. The main objective of this study is to prove the accuracy of the phase-field model in which the alternate minimization iteration and the spectral decompositi...

The main interest of this study is to analyze the effect of Poisson’s ratio (negative for auxetic materials) on the dynamic behavior of anti-trichiral structures: an experimental and numerical study is proposed. Using three-dimensional printing technology, anti-trichiral structures (cores and sandwiches) with different geometric parameters were pro...

Gears are one of the essential transmission systems in various industry sectors. The gear faults are widespread due to the severe conditions of their work. Therefore, gear failure diagnosis has become an important topic. This paper proposes a method for fault diagnosis in the dynamic model of a spur gear system using one of the statistical control...

During the machining process, the instantaneous cutting forces generate vibrations which reduce the effects of the machine’s performances. In general, the majorities of cutting force models assume that the cutting tool is geometrically perfect and focus only on the impact of different cutting parameters. Thus, several sources of errors in machining...

The primary aim of this study is to create a prototype that incorporates a coagulation, flocculation, and settling station. The prototype is intended to optimize the water recovery rate within storage basins and reduce the surface area required for sludge storage. To achieve this, the study will involve the design of treatment and de-watering syste...

Active Magnetic bearings (AMB) are widely used in the rotating machine. Its dynamic behavior is impacted by the AMB parameters. That’s why, a good selection of the bearing parameters is important to achieve an accurate performance of the rotating machine. This work attempts application of Particle Swarm Optimization (PSO) is applied to select the o...

Reducing energy consumption during the cutting processes is the key to an efficient manufacturing process. The best way to achieve that aim is to select correctly the cutting parameters, which can enhance the quality and efficiency of production. This study proposes an optimization for four functions such as energy consumption, surface roughness, c...

For any mechanism, and in the case of planetary gear (PG), the vibration response always has a good concept that can give information about the system in any case. It allows to clarify properly the crack defect characteristics of PG train.In fact, a lumped-parameter-model of PG system is used to study the impact of the internal excitations due to t...

In the industrial sector today, uncertainties pose a significant problem that impacts the performance of any material. Many studies are carried out to reduce the error’s effects. Uncertainty analysis is an important and necessary stage for conception under uncertainty conditions. The assessment of uncertainties must be taken into account in these s...

The widespread usage of electronic equipments in all vital existing sectors requires that these equipments are functional as long as necessary. In order to improve their lifetime, a reliability study should be carried out. Among the most decisive factors for the lifespan of electronic devices are the applied loads which are basically power, thermal...

Biocomposite materials have the potential to address some of the health and environmental issues we face today. These materials are made from renewable resources. In addition to their environmental benefits, biocomposites also offer advantages over traditional synthetic composites in terms of their mechanical properties and durability. For example,...

This article is dedicated to the development of a passive damping system for the reduction of vibrations of the Nacelle/Rotor of offshore wind turbines in the case of aerodynamic and hydrodynamic charges. The presence of vibration causes deflection at the top of the wind turbine structure, degradation of the blades and reduction of producing energy...

The interaction of a moving fluid with a structure present nowadays a particular interest in academic and industrial projects. This interaction gives rise to several physical phenomena such as the reaction of tall structures to winds and the vibration of turbine blades. Modeling both the structure and the fluid helps to understand these physical ph...

This present study proposed a heat sink filled with NANO-enhanced Phase Change Materials (NANOPCM). The Computational Fluid Dynamics software (CFD) ANSYS Fluent 2021R1 is adopted to resolve the governing equations. The equations model the heat transfer and the fluid flow inside the PCM cavity. The used PCM is the n-eicosane with a melting temperatu...

The knowledge of an atmosphere chemical composition is very important for environment protection purposes, risk analysis or new areas discovery. In this context different technologies, including optical and spectroscopic sensors, are employed to identify accurately the air molecules. However, the use of such technologies is limited due to complexit...

In a highly competitive industrial context, the maintenance field has relied in recent years on various tools such as artificial intelligence algorithms (AI algorithms), in order to achieve its main objective, which is the continuous availability of machines. Previous applications of these algorithms in machine monitoring were mainly relying on his...

PurposeThe applications of flax fibre-reinforced polymers are becoming widely prevalent, particularly in the industrial sector. Generally, damage in composite material represents one of the predominant behavioural phases. The present paper aims to characterize this phenomenon and its related mechanisms in flax/Elium laminate composite using both li...