S. Comas-Cardona

• PhD
• Professor at École Centrale de Nantes

The promising outcomes of dynamical system identification techniques, such as SINDy [Brunton et al. 2016], highlight their advantages in providing qualitative interpretability and extrapolation compared to non-interpretable deep neural networks [Rudin 2019]. These techniques suffer from parameter updating in real-time use cases, especially when the...

The promising outcomes of dynamical system identification techniques, such as SINDy (Brunton et al. in Proc Natl Acad Sci 113(15):3932–3937, 2016), highlight their advantages in providing qualitative interpretability and extrapolation compared to non-interpretable deep neural networks (Rudin in Nat Mach Intell 1(5):206–215, 2019). These techniques...

During Liquid Composite Molding, a fibrous reinforcement is impregnated with liquid resin. Process design requires knowledge of the reinforcement permeability for fluid flow, but until recently, there has been no standard available for its measurement. In 2023, following decades of benchmarking activities and a standardization project, an ISO stand...

In liquid composite molding processes, variabilities in material and process conditions can lead to distorted flow patterns during filling. These distortions appear not only within the same part but also from one part to another. Notably, minor deviations in the dry fibrous textiles cause local permeability changes, resulting in flow distortions an...

A numerical model is proposed to simulate significant yarn slippage and unweaving in woven fabrics using the Arbitrary Lagrangian Eulerian (ALE) method. Woven fabrics were modeled at the yarn scale using 1D ALE elements with additional slip displacement degrees of freedom (DOF). The relatively weak bending stiffness of the yarn was included using a...

The consideration and implementation of actions to reduce the environmental footprint of products and sectors are becoming major concerns. Recycling wind turbine blades and induced production wastes are becoming significant challenges due to the nature of the currently used materials, i.e., fiber-reinforced thermoset polymer composites, making it c...

The main idea behind “Quilted Stratum Process” (QSP ® ) is to create a flat blank made of unidirectional/woven thermoplastic prepreg patches instead of using uniformly shaped prepreg stack as is the case with standard thermostamping process. Thus, using QSP ® ; one can manufacture components with complex geometries by using nearly rectangular patch...

The paper's goal is to provide a simple unified approach to perform sensitivity analysis using Physics-informed neural networks (PINN). The main idea lies in adding a new term in the loss function that regularizes the solution in a small neighborhood near the nominal value of the parameter of interest. The added term represents the derivative of th...

The Zero wastE Blade ReseArch project (ZEBRA), led by the French technical research center IRT Jules Verne, is looking to accelerate the industry transition to circular economy by designing and manufacturing the first 100% recyclable wind blades, using the thermoplastic resin ELIUM®, developed by Arkema. To improve the infusion process, the objecti...

In the Resin Transfer Molding (RTM) process, a polymeric resin is injected inside a dry preform to fill the gaps around and inside the fiber tows. Simulating this process at the scale of the tows is challenging because of the computational cost associated to solving a three-dimensional dual-scale flow problem. In this work, a novel Dual-Scale Skele...

This paper aims to provide a machine learning framework to simulate two-phase flow in porous media. The proposed algorithm is based on Physics-informed neural networks (PINN). A novel residual-based adaptive PINN is developed and compared with the residual-based adaptive refinement (RAR) method and with PINN with fixed collocation points. The propo...

Tailored Fibre Placement (TFP) allows manufacturing net shape preforms with continuously varying orientations and thickness. This additive technology, combined with forming, enables the design of fiber reinforced composite parts with optimized fiber orientations. A new modelling strategy to simulate the forming of thin dry TFP preform without backi...

This paper aims to provide a machine learning framework to simulate two-phase flow in porous media. The proposed algorithm is based on Physics-informed neural networks (PINN). A novel residual-based adaptive PINN is developed and compared with traditional PINN having fixed collocation points. The proposed algorithm is expected to have great potenti...

In the frame of LCM processes, the mesoscopic architecture of a preform is defined by the sequential stacking of layers in the mold. Once the compaction is carried out, the precise orientation of layers and spatial distribution of tows is difficult to know with precision. The lack of this information can lead to a wrong prediction of properties. In...

The out-of-plane permeability of two glass fibre fabrics was measured by 26 institutions using silicone oil as a test fluid. Participants in this study were free to select the test procedure, specimen dimensions and data analysis method, provided that testing was carried out at three target fibre volume fractions, 46 %, 50 % and 54 %. While results...

One can compute the final deformation of a known geometry under specific boundary conditions using the constitutive laws of mechanics that describe their stress strain behavior. In such cases the initial geometry is known, and all operators mapping the deformation are defined on the reference domain. However, there are situations in which the final...

This paper reports the results of an international benchmark exercise on the measurement of fibre bed compaction behaviour. The aim was to identify aspects of the test method critical to obtain reliable results and to arrive at a recommended test procedure for fibre bed compaction measurements. A glass fibre 2/2 twill weave and a biaxial (±45°) gla...

Fibrous textiles are subjected to dry through-thickness compaction during most of the composites manufacturing processes. Usual tow models implemented in textile numerical simulations do not reproduce the tow widening occurring during the compaction. Nonetheless, this widening (that can reach 10%) would influence the internal microstructure of the...

“Quilted Stratum Process” (QSP ®) is a new process in the category of thermoplastic composite forming with the objective to locally strengthen the composite parts by strategically stacking discontinuous UD/woven prepregs while maintaining the short cycle time of about 1 min. Interply adhesion arising due to polymer tack plays an important role in Q...

Continuous fiber-reinforced thermoplastic composites can be produced by compression or consolidation processes at a temperature above the thermoplastic melting temperature. High production rates or high fluidity thermoplastic (TP-HF) viscosities can lead to large in-plane displacements of the fibrous network during the process. The same mechanisms...

“Quilted Stratum Process” (QSP®) is a new process developed by CETIM, Ecole Centrale de Nantes and their partners which is in the category of thermoplastic composite forming. Unlike the conventional thermoforming process, a QSP® preform stack consists of several discontinuous plies. Due to the inability of using the blank-holders in this process, t...

The mechanical efficiency of fiber-reinforced composite materials mainly depends on the alignment of fibers along the load paths arising from the boundary conditions applied to the part. On this basis, the Tailored Fiber Placement (TFP) consists in building a fibrous reinforcement by continuously laying down a tow on a plane backing material which...

Quilted Stratum Process" (QSP ®) is a unique thermoplastic composite forming process which locally strengthens the composite parts by strategically stacking discontinuous UD/woven prepregs. Interply adhesion is important in QSP ® because of resin-rich layer at ply-ply interfaces, inability to use blank holders and high temperature where the resin i...

Le procédé QSP ® est un procédé de formage d'une préforme composite thermoplastique optimisée constituée de patchs préimprégnés unidirectionnels et tissés discontinus. Les patchs sont découpés de façon à limiter les chutes, puis sont distribués stratégiquement dans la préforme à plat, chauffés et formés rapidement pour atteindre un temps de cycle c...

During compression of saturated fibrous reinforcement, the flow of the liquid can, under certain conditions, generate fiber-tows washout (in-plane movement of fiber-tows) due to the strong hydrodynamically induced force on the fibrous reinforcement. The objective of the study is first to detect experimentally the onset and measure the full-field ma...

Tows, partially constrained (tows within textile architecture) or free (single tows) exhibit movements and deformations, due to the various mechanical solicitations applied during manufacturing. During weaving or stitching, single dry tows undergo local compaction due to interlacing or stitch, leading to the evolution of the tows cross-section whil...

Composites manufacturing using the infusion process involves an unloading phenomenon due to the vacuum bag flexibility. Additionally, during impregnation, woven or non-crimp fabrics exhibit a dual-scale flow. Usual modeling of both phenomena assumes that the fibrous preform is a continuous medium with a varying permeability. Nonetheless, the permea...

In Liquid Composite Molding (LCM) processes, fabric layers are stacked in a mold which may be a few meters long and wide to build up a thickness of not more than a few millimeters. Resin is introduced to fill all the empty spaces between the fibers. As the in plane dimensions are a few orders of magnitude larger than through the thickness, flow of...

Classical dual-scale reactive simulations of the RTM process assume permanent intra-tow resin storage in the saturated domain. However, recent experimental investigations revealed that permanent storage is occurring only in a limited volume of the tows. In the remaining volume, fluid is released in the channels with a rate that depends on the archi...

Consolidation is a crucial step in manufacturing of composite parts with prepregs because its role is to eliminate inter- and intra-ply gaps and porosity. Some thermoset prepreg systems are toughened with thermoplastic particles. Depending on their size, thermoplastic particles can be either located in between plies or distributed within the inter-...

Fibrous fabrics are used in a variety of applications, among them, for structural composites. Most fabrics are efficiently manufactured from tows or yarns. During textile manufacturing or during fiber reinforced composites manufacturing, the fabrics and tows undergo several movements and deformations. Although there have been several attempts by di...

Thermoplastic matrix composites reinforced with glass fiber reinforcements are viewed as an alternative to thermoset matrix composites for structural components in the automotive field, as they allow for lower costs and higher production rates. However, the forming of thermoplastic composites from a preform made of discontinuous plies is more sensi...

Characterizing the response of compressed dry fibrous reinforcements is a key feature to control liquid composite molding processes. Considering preforms manufactured by automated dry fiber placement, supplementary information are needed, since cyclic loading occurs, during which the mechanical properties of tows evolve. In this way, an extensive c...

Fiber reinforcements used for structural RTM applications feature dual-scale porous microstructures. During injections, these microstructures induce intra-tow resin storage that affects, significantly in fast curing cases, the distribution of temperature, viscosity and degree of cure. Storage is considered permanent in the literature; however, to o...

The freedom of composite design can be improved by combining continuous and discontinuous prepregs. The forming of a pre-heated blank made of optimally oriented and distributed discontinuous prepreg plies may lead to unacceptable defects such as in-plane and out-of-plane wrinkles, sliding of plies over long distance, rotation of adjacent plies, ben...

Simulation tools are required to ease the determination of the optimal process parameters and injection strategy of short cycle resin transfer molding (RTM). The developed finite element method/volume of fluid numerical tool aims to simulate accurately and efficiently the flow of a reactive resin mixed on-line in a dual-scale porous reinforcement d...

The fundamental macroscopic material property needed to quantify the flow in a fibrous medium viewed as a porous medium is the permeability. Composite processing models require the permeability as input data to predict flow patterns and pressure fields. As permeability reflects both the magnitude and anisotropy of the fluid/fiber resistance, effici...

Fibrous composite reinforcements with enhanced permeability are of a particular interest for liquid composite molding processes requiring the fibrous preforms to be well impregnated by a viscous polymer. The aim of this work is to study the link between the reinforcement permeability and the geometrical parameters of its architecture, taking into a...

Thermoplastic matrix composites reinforced with glass fiber reinforcements are viewed as an alternative to thermoset matrix composites for structural components in the automotive field, as they allow for lower costs and higher production rates. However, the forming of thermoplastic composites from a preform made of discontinuous plies is more sensi...

This work addresses the numerical simulation of compression moulding of Sheet Moulding Compound (SMC) where the behaviour of the polymer is supposed Newtonian and thermal effects are neglected. The proposed model relies on the Stokes formulation combined with Lubrication Theory, following the approach developed in [2]. It is solved using a Finite E...

This research addresses the effects of quasi-UD non-crimp fabric (NCF) design parameters on the fabric architecture and on the permeability tensor. These fabrics are designed for the Liquid Resin Infusion (LRI) of large and thick composite parts. Three fabrics’ parameters intended to bring a flow enhancement to the NCF are investigated: the stitch...

Two experimental set-ups used to characterise the in-plane and through-thickness permeabilities of reinforcing textiles have been developed and are presented. Both the experimental testing and data processing techniques used have been selected to ensure that the characterisation is completed in an efficient and robust method, increasing the repeata...

Most Out-of-Autoclave prepregs (OoA) are only partially impregnated with resin. Their impregnation completes during the cure cycle, solely driven by the difference between atmospheric and vacuum pressure. Increased part length leads to an impregnation time gradient caused by the transient air flow inside the fibrous medium. In this work, a novel nu...

The construction of mesoscopic models of fiber washing effects during the high pressure resin transfer molding (RTM) process with thermoplastic polymers requires the knowledge of the limit of adhesion coefficients between dry and impregnated fabric reinforcement plies and the mold. To measure these coefficients, a new method is described. During RT...

Three different types of a quasi-unidirectional fabric have been produced and studied in order to reach the objective of the enhanced longitudinal permeability. The overall goal of the project TAPAS is to use the optimised fabric in a RTM process adapted to high fluidity polyamide 6,6. Microstructure study is undertaken with Scanning Electron Micro...

This paper provides a methodology for the modeling of heat transfer and polymer flow during direct thermoplastic injection pultrusion process. Pultrusion was initially developed with thermosets which have low viscosity. But the impregnation becomes a critical point with thermoplastics which exhibit higher viscosity. There are very few reported work...

The necessity to realize a mechanical study of tows at the fiber-scale comes from the fact that the quality of composite parts depends on spatial distribution of fibers and fiber-fiber interactions during automated placement. This paper presents the 3-D dynamic modeling of one fiber motion with an articulated bodies system. Complex shape composite...

Thermoplastic composites have an increasing demand in the automotive industry. However, their relatively high viscosity poses manufacturing challenges. Especially in the RTM process lower viscosities or process changes are required to overcome bundle deformation or preform washing. To improve the cycle time and the part quality CETIM is developing...

Partially impregnated prepregs allow the vacuum to be distributed throughout the laminate and can transport air and volatiles outside the part. Air flow through the laminate and the latency of the matrix during the curing cycle strongly influence the resin-fibre wetting process. Non-optimized curing cycle can cause incomplete wetting of the initial...

In order to model the resin flow through the complex double-scale porosity architecture of textile reinforcements, requiring rich numerical discretization, the Proper Generalized Decomposition (PGD) technique applied to the Stokes and Brinkman equations is employed in this study. The performed parametric study allows to identify the ratios of param...

Structural composite manufacturing relying on Liquid Composite Molding technologies is strongly affected by local variability of the fibrous reinforcement. Optical techniques using light transmission are used and allow field measurements of areal weight (and fibre volume fraction) of glass fibre reinforcement. The coupling of obtained areal weight...

In this study the multi-objective optimization of a fiber reinforced composite part will be presented. Additionally to the weight and the mechanical properties, its manufacturability with the Resin Transfer Molding process is considered during the optimization. For the last mentioned, a new CPU-time efficient method, called Process Estimator, was d...

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...

In this study the multi-objective optimization of a fiber reinforced composite part as a function of its mass, mechanical properties and manufacturability with the Resin Transfer Moulding process is presented. To verify the manufacturability a method for a fast, semi-analytical filling time calculation was developed, which takes into account the lo...

Due to the partial impregnation and limited pressure available for curing Out-of-Autoclave (OoA) prepreg, modeling the air transport through the tows becomes applicable. Focus is given on predicting the tow fill time for through thickness resin flow taking into account the air evacuation state. This work presents models that can be applied at diffe...

This article introduces a methodology to measure in-plane permeability of fibrous media using a transient one-dimensional air flow with absolute pressures ranging from 10³ to 10⁵ Pa. The method, based on the measurement of gas pressure at the boundaries throughout the transient flow, is convenient, clean and fast, avoids usage of a gas flow meter a...

The exact solutions of problems about bending of the corrugated beam are found and illustrated as an application to undulated yarns. The analysis of the solutions reveals the peculiarities of the projections of forces, moment and displacements on the axis equidistant to the tops of the crimp. These peculiarities permit to apply the asymptotic homog...

During forming operations of dry fibrous materials in order to get the composite preforms, the deformation mode is substantially determined by the occurring shear strains. Consideration of the material shear response namely from the theoretical point of view has gained high importance because multi-scale nature and anisotropy of fibrous materials c...

Three-dimensional reinforced sandwich structures are generally designed in order to provide optimal out-of-plane mechanical properties, beside traditional sandwiches which generally display satisfactory specific flexural properties but fatally insubstantial stiffnesses in the through-thickness direction. This paper deals with sandwich structures ma...

The theoretical prediction of mechanical characteristics of multi-scale fibrous materials gains more and more importance because it helps to omit expensive experimental procedures, to study the effects of different parameters on the global response of the material, and to “virtually” define the most important ones for the material design. This pape...

A methodology has been proposed for statistical characterization of transport behavior of a typical random fibrous medium, i.e. the Chopped Strand Mat (CSM). For any given digital images of fabric sample, statistical description of the random microstructure is employed to evaluate the permeability field, in the framework of the statistical continuu...

Variability in fiber architecture and content introduces randomness in transport and mechanical properties of textile reinforcements and composites. Assessment of robustness of both manufacturing processes and composite parts require to link fabric variability to dominant properties. Irregular injection flow patterns or defects in the final product...

The properties of final composite parts depend on properties of dry preforms often being formed over doubly-curved shapes. In this case the fibrous preforms exhibit intricate large deformations, including shear, tension, and bending modes. Although the bending stiffness of fibrous materials is small, in shaping of preforms, when wrinkling occurs, i...

Structural composite manufacturing in automotive industry requires short cycle times to be competitive against other material systems. Resin transfer molding (RTM) process is a viable process to manufacture composite parts when highly reactive resin with short curing cycle is used. Mixing of the components of the resin system is carried out at the...

In this international permeability benchmark exercise, in-plane permeability data for two reinforcement fabrics, obtained using a total of 16 different experimental procedures, were compared. Although, for each procedure, the results appear consistent, different procedures result in a scatter of up to one order of magnitude in principal permeabilit...

An efficient numerical approach is presented for the simulation of mold filling process with random fibrous permeability as input. Suitable dimension-reduction techniques are employed to represent all the random fields in the physical system. The required accuracy in tracking the moving resin flow front is guaranteed by the Level Set Method (LSM)....

The microporomechanical approach (via homogenization schemes) has been used and combined with triaxial tests to verify the Biot theory for the perfectly straight unidirectional fiber assembly in a previous paper [Tran T, Binetruy C, Comas-Cardona S, Abriak NE. Microporomechanical behaviour of perfectly straight unidirectional fiber material: theore...

Molding composites constituted of fiber reinforcements, resin and fillers is of prime interest for many transportation applications. Dealing with the flow of particle-filled resin in a fibrous network raises the issue of particle retention and viscosity increase. The present study aims at simulating such molding through an efficient coupling betwee...

The theory of poromechanics, most often used for macroscopically isotropic granular material, is applied to unidirectional fiber assemblies. When the deformation of the constituting fibers of those assemblies is taken into account during undrained forced compression, the Biot coefficients are expected to be lower than one. In the case of transverse...

The present paper aims at predicting the Biot coefficients for perfectly straight unidirectional (UD) fibre assemblies using micromechanical methods: Mori–Tanaka and Ponte Castañeda–Willis estimates. An experimental procedure, based on both uniaxial and triaxial material testing machines, is also detailed and applied to rubber fibre assemblies. The...

A key objective dealing with 3D sandwich structures is to maximize the through-thickness stiffness, the strength of the core and the core to faces adhesion. The Napco® technology was especially designed for improving such material properties and is under investigation in this paper. In particular, the potential of the process is characterized using...

When employing Liquid Composite Moulding (LCM) to mould composite parts, using particle-filled resins, certain problems may arise, such as the increased viscosity of the resin or the filtration of the particles. When the particle-filled resin is flowing, the fibrous reinforcement may act as a filter and so give rise to manufacturing defects. Inject...

During the manufacturing of particle-filled resin composite parts with a liquid composite molding (LCM) process, undesirable issues arise like resin viscosity increase or particles filtration. As the filled resin flow is taking place, the fibrous preform may act as a filter and hinder the even repartition of the fillers throughout the part or even...

The use of particle-filled resin to produce composite parts with a Liquid Composite Molding (LCM) process such as Resin Transfer Molding (RTM) raises the issue of the possible filtration of the particles by the fibrous preform during the impregnation stage. This may results in an uneven distribution of the particles throughout the part or even in d...

Depending on the target properties of a composite part, it may be necessary to add particulate fillers to the liquid resin before manufacturing. Cost reduction or flame resistance are examples of motivations for doing so. During the manufacturing of particle-filled resin composite parts with a LCM (Liquid Composite Molding) process, undesirable iss...

Liquid Composite Molding (LCM) processes are increasingly used to produce composite parts. Most of those processes involve compression of the fiber reinforcement and resin flow. In order to accurately model LCM processes, a good knowledge of fiber reinforcement behavior in compression is required. Several models have already been published, but non...

Liquid composite moulding processes are increasingly used to manufacture composite structures. Such processes combine compression of the fibre reinforcements (in dry and/or lubricated states) and resin flow. A better modelling of the compression of fibre reinforcements would improve the accuracy of hydro-mechanical coupling modelling involved in th...

Modelling LCM processes, where resin flow and compression of the fibre reinforcements are involved, requires a proper modelling of the fibre reinforcements behaviour in compression and to define how the permeability tensor evolves. The permeability measurement techniques based on fluid injection lead to data scattering. Using a material testing mac...

Composite manufacturing processes involve multi-scale phenomena. Equations governing mechanics, heat transfer and fluid flow dynamics can be derived in the scale of the problem to solve. This article focuses on addressing fluid flow simulation needs for Liquid Composite Molding processes using a generic mixed FE-SPH method. The SPH method is Lagran...

Several simulation programmes have been developed for the resin transfer molding (RTM) process, which is adapted for the manufacturing of cost-effective composite parts with high volume content. The Polymer and Composites Technology Department of the Ecole des Mines de Douai is working on the simulation of RTM-derived processes as a function of ind...

Resin Transfer Moulding (RTM) can be a very attractive single-step process for sandwich structure manufacturing. During an RTM injection, large deformation of the foam core material is present due to the pressure field developing while saturating the fibre-reinforced skins. Such effects induce poor dimensional accuracy of skins and core thickness....