Yves-Henri Grunevald

Composites Expertise & Solutions Sarl · R&D

This study focuses on the use of bio-based materials for structural purposes in the packaging field, which requires the identification of their mechanical properties at a representative scale. The mechanical properties of bio-based materials are more variable than those of traditional composite materials. In a standard characterization approach usi...

The present paper reports an experimental study coupled with a numerical modelling approach to simulate masonry walls strengthened with textile-reinforced mortar (TRM). This innovative reinforcing technique is based on high-strength fibre grids embedded into inorganic matrices, and it has recently been promoted for the seismic retrofitting of histo...

The phenomena occurring during curing process is one of the major issues to deal in order to improve the physical properties of a composite structure. In this work, a multi-instrumentation setup is conceived in order to have a better understanding of composites curing using different devices (tunnelling junction sensors, optical fibres and flexible...

We report on experimental and numerical investigations of textile reinforced mortar (TRM) strengthening systems, an innovative solution for reinforcing historical masonry structures. The experimental campaign presented in this paper is original and concerns two commercial TRM applications to single-leaf clay masonry panels. The proposed FE modellin...

This paper provides an illustration of all stages of primary aeronautical composite structure repair by using industrial tools and scientific methodologies, as well as numerical tools to simplify the cross-over analysis of the mechanical behaviour of the repaired area. Economically and scientifically speaking, one of the main challenges of composit...

A main challenge facing the structural applications of composite materials is related to the uncertainty in the material performance due to their inherent variabilities. Structural properties of composites are not only dependent on the manufacturing steps, but also on the constituent materials, reinforcement architecture and design choices. By intr...

A main challenge facing the structural applications of composite materials is related to the uncertainty in the material performance due their inherent variabilities. Structural properties of composites are not only dependant of the manufacturing steps, but also on the constituent materials, reinforcement architecture and design choices. By introdu...

Reinforcement angle orientation has a significant effect on the mechanical properties of composite materials. This work presents a methodology to introduce variable reinforcement angles into finite element (FE) models of composite structures. The study of reinforcement orientation variations uses meta-models to identify and control a continuous var...

In this paper, the monitoring patch is evaluated as an alternative instrumentation technique for aircraft-type composite structures, by means of the Multi-Instrumented Technological Evaluator. In this case, the goal is to evaluate the strength and failure modes of a carbon-epoxy composite plate with two drop-offs instrumented with a monitoring patc...

Ply thickness is one of the main drivers of the structural performance of a composite part. For stress analysis calculations (e.g., finite element analysis), composite plies are commonly considered to have a constant thickness compared to the reality (coefficients of variation up to 9% of the mean ply thickness). Unless this variability is taken in...

Non Destructive Testing (NDT) by active InfraRed Thermography (IRT) of bonded Carbon Fibers Reinforced Plastic (CFRP) laminates is a very challenging issue. Difficulties come from the weak contrast between the thermal properties of constitutive parts, the small thickness of the epoxy joint and also the depth of the bonded interface. The strategy co...

Ces travaux abordent la question du Contrôle Non Destructif (CND) par Thermographie In-fraRouge (TIR) des réparations par collage structural de stratifiés carbone-époxyde. Les difficultés d'investigation de ce type d'assemblage proviennent du faible contraste de propriétés thermiques entre les différents éléments constitutifs de la réparation. Pour...

An original approach based on active Infrared Thermography (IT) addresses the very challenging issue of the non destructive analysis of bonded repaired CFRP laminates. Difficulties come from the weak property contrast between parts of repaired assemblies and thickness of the joint. Strong attention is given here to the control of experimental tests...

This chapter deals with the issues and main challenges concerning large repair of primary composite structures. Feedback about use of composite parts, during a million cumulated flight hours, demonstrate the higher damage tolerance of composite solution but also the necessity to define optimized repair solutions. A global vision of repair is propos...

Ce travail s’intéresse à l’évaluation de variations spatiales de grandeurs morphologiques au sein de plaques CFRP. Les grandeurs étudiées sont les variations d’orientation des fibres dans le plan, ainsi que les variations d’épaisseur des plis. L’objectif de ce travail est, dans un premier temps, de proposer des lois mathématiques modélisant les var...

In this paper, the classic embedding technique, with bared sensors, and a recent proposal, the monitoring patch, are compared with the aim to improve the composites in-core instrumentation. The monitoring patch emerges with the need to industrialize sensors integration inside composite structures; thus, a complete evaluation of its mechanical perfo...

In this paper, a new technique is proposed to confine concrete columns using GFRP-prefabricated bonded shells and a shrinkage-compensating cement mortar. The confinement is performed with three identical shells, each of which contains two stepped lap joints at their ends. The main advantage of this technique is that the shells can be directly assem...

In this paper, the Multi-Instrumented Technological Evaluator (MITE) is presented as an alternative approach to study the mechanical performance of composite structures. The goal is to have an enrichment of the calculus-testing dialogue by means of the interaction of four complementary divisions: the composite structure, the multi-axial testing mac...

In this paper, the Multi-Instrumented Technological Evaluator (MITE) is presented as an alternative approach to study the mechanical performance of composite structures. The goal is to have an enrichment of the calculus-testing dialogue by means of the interaction of four complementary divisions: the composite structure, the multi-axial testing mac...

An innovative bonded repair evaluation, through the design of a detail-sized evaluator and representative from the industrial application, is proposed thanks to the study of the interface behaviour. This paper deals with a primary major phase which follows three stages: First, non-standard shear tests have been conducted, Secondly, with the geometr...

Experimental protocol of Abrasive Water Jet (AWJ) milling is presented for composite material machining. It deals with a model concerning on one side, the optimal abrasive flow versus pressure, the diameter of tube and machined depth, and on the other, the feed rate versus the pressure, the tube diameter, the ratio of abrasive optimum flow and the...

In this work, a multi-instrumentation setup is conceived in order to have a better understanding of composites curing by using different devices: tunnelling junction sensor (TJS), flexible ultrasonic transducers (FUT) and thermocouples. The sensors are simultaneously embedded or placed on the surface of a thick carbon-epoxy plate for monitoring its...

Regardless of the high ‘strength to mass’ ratio, specially for parts made of carbon fiber reinforcements, the reduction in terms of mass as well as in terms of cost of a composite aircraft structure are below than those expected. One of the challenges that restrain the optimal use of composites in an aircraft structures is the difficulty to deal wi...

This paper introduces part of the results of the project called “Instrumentation with Multi-sensor for Composite Materials and structures (I2MC)” supported by RTRA STAE foundation. The main goal of the paper is to show the complementarities of different monitoring devices such as flexible ultrasonic transducers (FUT), micro-structured (MOF), and DT...

In this work, we propose to use a highly birefringent microstructured optical fiber (MOF) in which a fiber Bragg grating (FBG) sensor is written to measure the transversal strain built up in a CFRP part during its manufacturing. It will be combined with FBGs in single mode fibers (SMF) protected from the transverse effects to identify the longitudi...

This study deals with the qualification and quantification of several sources of variability in composite structures which appear at each stage of manufacturing. In order to proceed with our study, 12 CFRP plates are manufactured from an UD prepreg M10.1/38%/UD300/CHS. The plates are cured in autoclave and have a quasi-isotropic lay-up. The first s...

An innovative method to evaluate composite repairs is proposed. This method is based on the study of representative structures under complex loading cases. The feasibility of the method is demonstrated through the repair of a double-step lap test coupon as example. The specimen, which is 600 mm long and 130 mm wide, is made of M10.1/38%/UD300 CHS 4...

This paper introduces a part of the results spinning off the project called “Instrumentation with Multi-sensor for Composite Materials and structures (I2MC)” supported by RTRA STAE foundation. The main goal of the paper is to show the complementarity of different devices such as flexible ultrasonic transducers (FUT) and micro-structured (MOF) and D...

The design flexibility of photonic crystal optical fibres (PCFs) offers new possibility in the field of optical fibre sensing. One of those is the possibility to integrate fibre Bragg grating fabricated in PCFs into composite material without disturbing the structural integrity. FBG-based sensors have already proven their ability to measure strain...

Two scales for the study of a step-lap repair are presented. To perform the repair machining, an Abrasive Water Jet process (AWJ) is used in order to obtain a step-lap shape. A single step-lap machining is performed to create some tensile coupons in order to identify the shear behavior of the adhesive. Tensile tests emphasize difficulties in obtain...

This paper introduces a methodology to solve open issues associated to "on field" repair of primary principal structures for composites. If a repair is mandatory, it leads to a costly immobilization. Structural damage needs a case by case solution including design, stress analysis, damaged zone removal, patch construction, set-up and finishing. Fur...

This paper introduces a methodology to solve opened issues associated to "on field" large repair of primary principal structures for composites. If a repair is mandatory, it leads to a costly immobilization. Structural damage needs a "case by case" solution including design, calculation phases, damaged zone removal, patch construction, set-up and f...

An innovative repair process and evaluation are proposed. Firstly, the originality of this work consists on the process used for the repair milling: an Abrasive Water-Jet milling. A double-step lap coupon is chosen to demonstrate the feasibility of the milling process. This specimen is made of M10.1/38%/UD300 CHS 460 from Hexcel Composites. After m...

Sensor embedding is one of the main operations in dealing with composites incore instrumentation. In this work, an alternative encapsulation technique called “monitoring patch” is proposed to achieve correct sensor embedding, to facilitate the industrialised instrumentation procedure and to adapt the sensors according to the geometry and material h...

In the framework of the research program called Multisensor Instrumentation for Composite Materials (I2MC), the monitoring patch is proposed as alternative sensor embedding technique. In order to know the influence of the variability in the patch fabrication procedure, a numerical study is carried out. A gap comparison between the different geometr...

Composite in-core instrumentation with silica sensors (Sich), piezoelectric (PZT) and mechanic-electrical (MEMS) is being multiplied but its applications stay limited. This technique can be treated by two ways. The first one deals by placing the sensor directly in the structure plies. The second is through a sensor encapsulation inside a known envi...

Des éprouvettes carbone/époxy pour évaluer la qualité d’une réparation en escalier sont usinées, réparées puis testées mécaniquement. L’usinage préalable à la phase de réparation est effectué par Jet d’Eau abrasif, sous forme de marches régulières de ratio 1/30, et dont la profondeur correspond à l’épaisseur d’un pli. Le relâchement des contraintes...

The study of sensor – structure duality is one of the main facts to analyze in composites incore instrumentation. In this work, the concept of “monitoring patch” is proposed in order to reduce the variability effects produced by placing the sensor alone. The monitoring patch will be developed in order to facilitate the instrumentation process and t...

This study concerns the central reinforced zone of a composite structural specimen. In order to estimate the strain distribution during a series of three and four-point bending tests, several optical fiber Bragg grating sensors have been embedded in various levels of the ply stack. Simultaneously, surface strain field measurements by 3-D digital im...

The present paper deals with the use of optical fibers with Bragg gratings for the identification of process-properties relations for composite structures. This study relates a 7 year-experience in the field of process and mechanical characterization of composite parts. It highlights some major topics in terms of technological issues such as sensor...

Advanced optical measurement techniques are used to analyze the mechanical behavior of a composite structure submitted to bending tests. This is carried out by considering a beam type specimen which presents design singularities such as important thicknesses, ply drop off zones and a reinforced zone. This study concerns the central reinforced zone...

This paper is a continuation of our previous study [Mulle M, Collombet F, Olivier P, Grunevald Y-H. Assessment of cure residual strains through the thickness of carbon–epoxy laminates using FBGs, part I: elementary specimen. Compos Part A 2008. doi:10.1016/j.compositesa. 2008.10.008] pertaining to the assessment of autoclave cure-induced strains th...

The HexFIT™ is a semi-product used for large structures manufactured by the RFI process. In this work, large plate made of a quasi-isotropic lay-up is considered. The presented study aims at mechanically characterizing and identifying the process impact for such a structure. NDT (US & IR) are first used to highlight material heterogeneities and thi...

Résumé La proportion de matériaux composites dans le domaine des transports en général et l'aviation en particulier est en pleine croissance. Les dimensions maximales des structures unitaires sont elles aussi en croissance. La maitrise des outillages nécessaires à la production de telles pièces composites devient un enjeu stratégique car jouant un...

Today aeronautical programs show the difficulty to satisfy at the same time technical, economical and schedule requirements when they are associated to the development and industrialization of full composite commercial airplane. These reveal numerous issues such as the upstream understanding of new architecture, their industrialization, maintenance...

Résumé Le perçage par enlèvement de matière des matériaux composites est souvent accompagné de dommages de natures différentes. Pour contourner cette opération d'usinage par enlèvement de matière, l'obtention de trous par moulage est la solution préconisée dans le cadre de cette étude. Pour valider ce procédé, des essais de comportement mécanique o...

Variability of thermo-mechanical properties within a composite part is a well known issue. It is problematic at the early stage of structural design. This variability being generated during the processing phases, the characterisation of the initial state of a structure becomes a crucial operation. A first step to this objective is presented in this...

The present paper deals with the use of optical fibers with Bragg gratings for the identification of process-properties relations for composite structures. This study relates a 7 yearexperience in the field of process and mechanical characterization of composite parts. It highlights some major topics in terms of technological issues such as sensor...

The present paper deals about the use of optical fibers with Bragg gratings for the identification of process-properties relations for composite structures. This study relates a 6 year-experience in the field of process and mechanical characterization of composite parts. It highlights some major topics in terms of technological issues such as senso...

Optical fibre with Bragg gratings sensors (FORB) are used to undertake measurements during the life cycle of composite structures (from manufacture to ruin). In this aim, the advantage of composite materials to be in situ instrumented is considered. We present how the many technological difficulties specific to the manufacturing process units are r...

This paper deals with a mixed experimental–theoretical approach aiming to evaluate information given by optical fiber Bragg gratings embedded in carbon–epoxy laminates submitted to thermal expansion. FBG instrumented elementary and structural specimens are considered. The study is undertaken through a comparison of values obtained on the one hand e...

Multi-disciplinary optimization (MDO) of composite structures shall help tomorrow’s product managers to make crucial trade-off decisions and reduce the time-to-market of innovative concepts. In this contribution, the authors present a computational chain developed for the purpose of the optimization, both technical and economical, of advanced compo...

The main topic of this paper deals with the stress analyses—tests dialogue in composite structures considering the influence of the manufacturing conditions of composite material within the structure. The scientific interest of embedded instrumentation exploited through a multiscale approach featuring optical fibers with Bragg gratings is discussed...

This paper deals with the challenge related to the improvement of the dialogue “calculation - test” in the design of composite structures by taking into account the influence of the manufacturing conditions of the composite material within the structure in the frame of a multiscale method. The incidence of discrepancies on the meso and the macro sc...