Chady Ghnatios

Chady Ghnatios
Notre Dame University-Louaize · Mechanical engineering department

PhD Mechanical Engineer

About

85
Publications
5,381
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
605
Citations
Introduction
Chady Ghnatios currently is an assistant professor at the Department of Mechanical Engineering, Notre Dame University-Louaize. Chady's main research interests are Materials Engineering, computational mechanics, model reduction and data-driven modelling.
Additional affiliations
June 2013 - February 2014
Ecole Centrale de Nantes
Position
  • Research Associate

Publications

Publications (85)
Article
Full-text available
Soft packaging is crucial in food industries. Packages are essential in products protection and currently polymers films are the most suitable materials in this domain. Thus, multi-layered films are designed to provide all necessary properties. Packages have an increasing marketing role as new designs attract more customers. Being able to modify th...
Article
The 3D printing of continuous fiber-composite materials can widen their industrial applications. This paper presents a modeling effort and an wrapping and deformation estimation during 3D printing. We first perform a thermal simulation; by leveraging the thermal results, we conducted a deformation simulation via proper generalized decomposition. We...
Article
Full-text available
Electromagnetic field propagation inside composite materials represents a challenge where fiber-scale simulation remains intractable using classical simulation methods. The present work proposes an original 3D simulation with a mesh resolution fine enough to resolve the fiber scale, thanks to the use of Proper Generalized Decomposition (PGD)-based...
Article
Full-text available
A nonparametric method assessing the error and variability margins in solutions depicted in a separated form using experimental results is illustrated in this work. The method assess the total variability of the solution including the modeling error and the truncation error when experimental results are available. The illustrated method is based on...
Conference Paper
The study involves applying the inverse dynamics to calculate the 3-dimensional (3D) reaction forces and moments at the lower limbs namely: hip, knee, and ankle joints. The study is specific to performing the Lebanese folkloric dance known as the “Dabke jump”. The aim is to compare the impact forces generated at the three joints. Also envisioned is...
Article
Full-text available
Additive manufacturing is an appealing solution to produce geometrically complex parts, difficult to manufacture using traditional technologies. The extreme process conditions, in particular the high temperature, complex interactions and couplings, and rich metallurgical transformations that this process entails, are at the origin of numerous proce...
Article
Full-text available
A Correction to this paper has been published: https://doi.org/10.1007/s12289-021-01638-4
Chapter
Book Series Editorial Board John Michopoulos, Naval Research Laboratory David Rosen, Georgia Institute of Technology Chris Paredis, Georgia Institute of Technology Judy Vance, Iowa State University This is the second volume in this book series that aims to capture advances in computers and information in engineering research, especially by research...
Article
The need of solving industrial problems using faster and less computationally expensive techniques is becoming a requirement to cope with the present digital transformation of most industries. Recently, data is conquering the domain of engineering with different purposes: (i) defining data-driven models of materials, processes, structures and syste...
Article
Full-text available
A novel Model Order Reduction (MOR) technique is developed to compute high-dimensional parametric solutions for electromagnetic fields in synchronous machines. Specifically, the intrusive version of the Proper Generalized Decomposition (PGD) is employed to simulate a Permanent-Magnet Synchronous Motor (PMSM). The result is a virtual chart allowing...
Article
Full-text available
Non-intrusive approaches for the construction of computational vademecums face different challenges, especially when a parameter variation affects the physics of the problem considerably. In these situations, classical interpolation becomes inaccurate. Therefore, classical approaches for the construction of an offline computational vademecum, typic...
Article
Full-text available
Microwave (MW) technology relies on volumetric heating, where thermal energy is induced from an electromagnetic field. Nowadays, the main drawback of this technology is that the complex physics involved in the conversion of electromagnetic energy into thermal energy is not entirely understood and controlled. The main objective of this work is to mo...
Conference Paper
Full-text available
Composites are the revolutionary materials that were developed for the ease of the technology. Similar to all families of materials, composites are being extensively studied nowadays. One of the composites ‘main studies is the homogenization study to determine composites modulus of elasticity function of multiple variables based on differentiating...
Article
Full-text available
SMC processes involve a highly concentrated dispersion of chopped fibres into a resin, placed into a preheated mould, that closes rapidly (about 40 mm/s) squeezing the reinforced resin, inducing the mould filling accompanied of the fibres induced orientation that influences the mechanical properties of the final part. Several issues compromises its...
Article
Full-text available
In this work we develop a void filling and void motion dynamics model using volatile pressure and squeeze flow during tape placement process. The void motion and filling are simulated using a non-local model where their presence is reflected in the global macroscale behavior. Local pressure gradients during compression do play a critical role in vo...
Article
Full-text available
This paper analyzes the ability of different machine learning techniques, able to operate in the low-data limit, for constructing the model linking material and process parameters with the properties and performances of parts obtained by reactive polymer extrusion. The use of data-driven approaches is justified by the absence of reliable modeling a...
Article
Composite manufacturing processes usually proceed from pre‐impregnated preforms that are consolidated by simultaneously applying heat and pressure, so as to ensure a perfect contact compulsory for making molecular diffusion possible. However, in practice, the contact is rarely perfect. This results in a rough interface where air could remain entrap...
Article
This work focuses on determining the homogenized elastic properties of concrete mixtures containing randomly oriented chopped inclusions using soft computing techniques, to identify optimal inclusion ratios. It also addresses the efficient resolution of the inverse problem, to identify the elastic properties of the constituents from those of the mi...
Article
Full-text available
Biphasic soft materials are challenging to model by nature. Ongoing efforts are targeting their effective modeling and simulation. This work uses experimental atomic force nanoindentation of thick hydrogels to identify the indentation forces are a function of the indentation depth. Later on, the atomic force microscopy results are used in a GENERIC...
Article
This work aims at proposing a new procedure for parametric problems whose separated representation has been considered difficult, or whose SVD compression impacted the results in terms of performance and accuracy. The proposed technique achieves a fully separated representation for layered domains with interfaces exhibiting waviness or – more gener...
Article
In the past decade, data science became trendy and in-demand due to the necessity to capture, process, maintain, analyze and communicate data. Multiple regressions and artificial neural networks are both used for the analysis and handling of data. This work explores the use of meta-heuristic optimization to find optimal regression kernel for data f...
Article
Full-text available
The present work aims at proposing a new methodology for learning reduced models from a small amount of data. It is based on the fact that discrete models, or their transfer function counterparts, have a low rank and then they can be expressed very efficiently using few terms of a tensor decomposition. An efficient procedure is proposed as well as...
Conference Paper
Microwave (MW) heating relies on volumetric heat sources due to induction and dielectric phenomena. The main drawback of this technology today is that the complex physics involved in the conversion of electromagnetic energy to thermal energy is not fully understood or even controlled. To overcome this issue, we propose the following work which cons...
Conference Paper
In this work we make use of the advantage offered by model order-reduction techniques to identify the properties of Non-Newtonian fluids using the vane test. A response surface depending on the parameters of the vane test is constructed to this aim. A power-law fluid is retained to illustrate this process and the vane test is simulated as a functio...
Conference Paper
This work aims at providing a parametric solution of LCM processes, and in particular RTM, when the location of the injection gate is assumed being a model parameter. It is well known that parameters can be easily considered as model extra- coordinates within the Proper Generalized decomposition framework. Then, the use of separated representations...
Article
Monitoring of cutting tool wear is crucial in machining operations where planning for longer tool life would result in economical savings. While deterministic and stochastic methods were sought for identifying optimal cutting conditions, efficiency and/or accuracy of the generated model fits were found to suffer when dealing with large number of va...
Conference Paper
Spirometer testing is considered the most common method used to evaluate the pulmonary system. It diagnoses asthma, chronic obstructive pulmonary disease (COPD) and other conditions that affect breathing. Nowadays many pharmaceutical companies produce spirometer devices for patients with asthma, designed for home use. However, the machines are repl...
Preprint
Industrial production lines often involve multistage manufacturing processes with coupled boundary conditions. The output of a process is the input of another processing stage. The end product of such production line is complicated to optimize since its simulation includes countless number of parameters and degrees of freedom. Therefore, incorporat...
Article
Automation is conquering new fields on a daily basis. Aiming for faster and more reliable products, industrials as well as researchers are oriented into automation. Non-destructive testing as well as defect quantification is not an exception. In fact, decisions with minimum allowable error are sought in real-time when facing any potential defect. I...
Article
Full-text available
Nowadays, human joints specifically movable are active research topics. The lack of effective replacements and the inefficient natural healing of these joints hinders any athlete from pursuing his career if injured in his joints. Therefore, researchers are testing innovative soft materials and biphasic materials as replacements of human joints. How...
Conference Paper
Cross-linked polyethylene (XLPE) is a thermoset polymeric material extensively used in the industry, including in firefighting systems, hot water and sanitary piping, and for the insulation of electric cables. The cross-linking of polyethylene increases its performance while reducing its recyclability. A recent approach considers processing XLPE wa...
Conference Paper
In machining, tool life is the measure that gives manufacturers fundamental indications on useful tool utilization. In this work, investigated is the influence of turning parameters such as spindle speed, depth of cut, and tool feed on tool life. Literature-reported studies typically utilize Taguchi orthogonal array method for experimental design w...
Article
Full-text available
Nowadays, the production of large pieces made of thermoplastic composites is an industrial challenging issue as there are yet several difficulties associated to their processing. The laserassisted tape placement (LATP) process is an automated manufacturing technique to produce long-fiber reinforced thermoplastic matrix composites. In this process,...
Article
The aim of this work is to derive a stabilized mixed formulation for flow problems while using a domain decomposition technique. Therefore, we are generalizing the stabilized finite elements method using Galerkin Least Squares (GLS), into a stabilized mixed formulation valid for the separated representation, as used in the Proper Generalized Decomp...
Article
Full-text available
Many electrical and structural components are constituted of a stacking of multiple thin layers with different electromagnetic, mechanical and thermal properties. When 3D descriptions become compulsory the approximation of the fields along the thickness direction could involve thousands of nodes. To circumvent the numerical difficulties that such a...
Conference Paper
Microwave (MW) technology relies on volumetric heating. Thermal energy is transferred to the material that can absorb it at specific frequencies. In this paper, a coupled thermic and electromagnetic model is proposed in order to simulate the emerging process of microwave heating for composite materials. Solving the problem in a laminated composite...
Conference Paper
Full-text available
Composites manufacturing processes usually involve multi-scale models in both space and time, highly non-linear and anisotropic behaviors, strongly coupled multi-physics and complex geometries [1]. In this framework, the use of simulation for real-time decision making directly in the manufacturing facility is still precluded nowadays [2]. In this w...
Article
Understanding sliding and load-bearing mechanisms of biphasic soft matter is crucial for designing synthetic replacements of cartilage, contact-lens materials or for coating medical instruments. Interstitial fluid pressurization is believed to be the intrinsic load-carrying phenomenon governing the frictional properties. In this study, we have char...
Article
Full-text available
Composites manufacturing processes usually involve multiscale models in both space and time, highly non-linear and anisotropic behaviors, strongly coupled multiphysics and complex geometries. In this framework, the use of simulation for real-time decision making directly in the manufacturing facility is still precluded nowadays, in spite of the imp...
Conference Paper
The effective modeling of the flow of fresh concrete materials in settings such as that of the vane test is a challenging process that is the object of ongoing research. Previous works modeled concrete and cement pastes as solids subjected to yielding or as Bingham or power-law fluids, both in two or three dimensions. Of the existing models, those...
Article
Full-text available
Automated fibre placement (AFP) is an incipient manufacturing process for composite structures. Despite its conceptual simplicity it involves many complexities related to the necessity of melting the thermoplastic at the interface tape-substrate, ensuring the consolidation that needs the diffusion of molecules and control the residual stresses inst...
Conference Paper
Microwave (MW) technology relies on volumetric heating. Thermal energy is transferred through electromagnetic fields to materials that can absorb it at specific frequencies. The principal objective of this work is to model and simulate the interactions of the MW field with a composite laminated part, consisting of a stack of layers of different ori...
Conference Paper
The enhanced design flexibility provided to the thermo-forming of thermoplastic materials arises from the use of both continuous and discontinuous thermoplastic prepregs. Discontinuous prepregs are patches used to locally strengthen the part. In this paper, we propose a new modelling approach for suspensions involving composite patches that uses th...
Conference Paper
Thermoplastic composites are attractive because they can be recycled and exhibit superior mechanical properties. The ability of thermoplastic resin to melt and solidify allows for fast and cost-effective manufacturing processes, which is a crucial property for high volume production. Thermoplastic composite parts are usually obtained by stacking se...
Article
Thermoplastic composites are attractive because they can be recycled and exhibit superior mechanical properties. As part of a more general research effort, in this paper attention is paid to squeeze flow of continuous fiber laminates. In the case of unidirectional prepregs, the ply constitutive equation, when elastic effects are neglected, can be m...
Article
This paper presents some insights into the determination, using the Proper Generalized Decomposition, of multiple solutions of nonlinear parametric partial differential equations. Although the Proper Generalized Decomposition (PGD) is well suited for computing the solution of, possibly nonlinear, parametric problems that vary smoothly with a physic...
Article
Frame structures have been traditionally represented as an assembling of components, these last described within the beam theory framework. In the case of frames involving complex components in which classical beam theory could fail, 3D descriptions seem the only valid route for performing accurate enough analyses. In this work we propose a framewo...
Article
The ultrasonic compaction might be a suitable technique to obtain well compacted composite laminates in order to implement them in out-of-autoclave automated curing processes. This procedure generates an ultrasonic vibration over the laminate that makes the resin heat and allows the composite plies to be compacted. The numerical study of this heat...
Article
Friction Stir Welding (FSW) is a welding technique which since its invention in 1991 is of great interest to the industry for its many advantages. Despite being widely used, its physical foundations and its relation to the technological parameters of the process are not known in detail. Numerical simulations are a powerful tool to achieve a greater...
Article
LCM simulation is computationally expensive because it needs an accurate solution of flowequations during the mold filling process. When simulating large computing times are not compatiblewith standard optimization techniques (for example for locating optimally the injection nozzles)or with process control that in general requires fast decision-mak...
Article
In the numerical modeling of composite materials and structures, microscopic heterogeneities introduce the need for defining homogenized properties depending on microscopic details. Real time image-based calculations in the framework of the on-line control of manufacturing processes demands the prediction of the local homogenized properties of a he...
Article
In the numerical modeling of composite materials and structures, microscopic heterogeneities introduce the need for defining homogenized thermal conductivities that depend on microscopic details. There are many techniques for performing computational homogenization. However image-based simulation introduces a new constraint, that of real time image...
Article
New out-of-autoclave layer-by-layer curing techniques require the use of an in-situ compaction device. Ultrasonic compaction can be a suitable system to achieve this goal. In the ultrasonic compaction, a pressure cylinder is excited over the composite laminate at a certain frequency. The vibration produces the heating of the resin of the plies, due...
Article
Full-text available
The solution of 3D models in degenerated geometries in which some characteristic dimensions are much lower than the other ones - e.g. beams, plates or shells - is a tricky issue when using standard mesh-based discretization techniques. Separated representations allow decoupling the meshes used for approximating the solution along each coordinate. T...
Article
Nowadays thermoplastic composite materials are more and more used due to their specific excellent mechanical properties and a good recyclability. However, many difficulties are encountered during their forming processes, specially in the case of thermoplastic composites –TPC–. Therefore, consolidation of thermoplastic composites is becoming one of...
Article
Separated representations allow substituting the resolution of 3D models by a sequence of three one-dimensional problems [1]. This route is especially suitable when models are defined in hexahedral domains. When it is not the case, different possibilities exist. In a former work [2], we explored the route of immersing the domain into a hexahedral d...
Article
Automated tape placement (ATP) is a process recently developed for the production of large parts (plates, shells) made of thermoplastic composites. In ATP a tape is placed on the previous ply and welded by a local heating and pressure to build up a laminated structure. The numerical modeling of such a process is a challenging issue since the therma...
Article
Full-text available
The modeling of composites manufacturing processes remains today a scientific challenging issue despite the impressive progress reached in mechanical modeling, numerical analysis, discretization techniques and computer science during the last decade. Indeed, composite manufacturing involves highly non-linear anisotropic behaviors and strongly coupl...
Article
Composite materials and their related manufacturing processes involve many modeling and simulation issues, mainly related to their multi-physics and multi-scale nature, to the strong couplings and the complex geometries. In our former works we developed a new paradigm for addressing the solution of such complex models, the so-called Proper Generali...
Article
Dynamic Data-Driven Application Systems-DDDAS-appear as a new paradigm in the field of applied sciences and engineering, and in particular in Simulation-based Engineering Sciences. By DDDAS we mean a set of techniques that allow to link simulation tools with measurement devices for real-time control of systems and processes. In this paper a novel s...
Article
This paper concerns the real time control of the boundary layer on an aircraft wing. This new approach consists in heating the surface in an unsteady regime using electrically resistant strips embedded in the wing skin. The control of the boundary layer's separation and transition point will provide a reduction in friction drag, and hence a reducti...