This diploma thesis deals with the subject of modeling high strength glued joints which are used during barrier crashtest simulations according to EuroNCAP methods. The purpose of the thesis is to design a metodology of modelling glued joints which will give acceptable results of its behavior during experiment.

This diploma thesis deals with the design of door frame curvature, meant for rail vehicle. Flat glass is adhesively bonded onto the curved door frame and due to the elastic deformation the door frame bends backwards. Hence the door frame must be bend with reserve so that the elastic deformation is covered. Finite element analysis of currently manufactured door with constant curvatere has been carried out, with this analysis it has been checked that the chosen problem approach is suitable. Design of door frame curvature is then made for door frame with combined curvature (different for lower and upper part of door frame). The aim of this thesis was to design the curvature so that after glass is bonded onto it, the door frame will have the right dimensions.

Fiber reinforced polymer (FRP) composites are considered very promising for infrastructure applications such as repair, rehabilitation and replacement of deteriorated bridge decks. However, there is lack of proper understanding of the structural behavior of FRP decks. For example, due to the localization of load under a truck tire, the conventionally used uniform patch loading is not suitable for performance evaluation of FRP composite deck systems with cellular geometry and relatively low modulus (compared to concrete decks). In this current study, a simulated tire patch loading profile has been proposed for testing and analysis of FRP deck. The tire patch produced significantly different failure mode (local transverse failure under the tire patch) compared to the punching-shear mode obtained using the conventional rectangular steel plate. The local response of a cellular FRP composite deck has been analyzed using finite element simulation and results are compared with full scale laboratory experiment of bridge deck and structure. Parametric studies show that design criteria based on global deck displacement is inadequate for cellular FRP deck and local deformation behavior must be considered. The adhesive bonding method is implemented for joining of bridge deck panels and response of structural joint analyzed experimentally. Strength, failure mode and fatigue life prediction methodologies for a cellular FRP bridge deck are presented in this dissertation. / Ph. D.

Les joints adhésifs sont de plus en plus utilisés dans des structures industrielles critiques. Ils sont donc susceptibles de subir des chargements dynamiques complexes. Les méthodes de caractérisation dynamiques existantes ne caractérisent pas seulement le joint adhésif, mais l'assemblage collé tout entier. Cette thèse propose une méthode innovante pour caractériser un joint adhésif sous sollicitations dynamiques multiaxiales. La méthode expérimentale repose sur trois éléments principaux: i) un système de barres d'Hopkinson conventionnel (SHPB), ii) une nouvelle géométrie d'éprouvette, nommée DODECA, qui permet d'appliquer trois chargements multiaxiaux différents et iii) des mesures locales de déformation et de contrainte par corrélation d'images. La contrainte et la déformation dans le joint adhésif sont estimées directement à partir des données expérimentales pendant le chargement jusqu'au point de rupture. Une autre approche basée sur la méthode FEMU (Finite Element Model Updating) a été utilisée pour compléter le modèle du joint adhésif. Une méthode inverse numérique a été développée pour obtenir les paramètres élastiques, plastiques et de rupture du joint adhésif. De plus, des outils qualitatifs ont été proposés pour estimer les incertitudes sur les paramètres identifiés. Ce travail a prouvé l'intérêt de l'imagerie rapide locale pour caractériser les joints adhésifs.Cette méthode innovante a été validée sur une autre éprouvette nommée BIADH45. Cette dernière étude a aussi mis l'accent sur de nouveaux domaines de recherche : en particulier, le rôle des interfaces dans la rupture du joint adhésif et l'intérêt des substrats en CMO dans la caractérisation dynamique des joints adhésifs. / Adhesive joints are increasingly employed for bonding critical parts of industrial structures. Therefore, they are subject to complex dynamic loadings. Existing dynamic characterization techniques do not characterize only the adhesive joint, but the complete assembly. This thesis proposes an innovative experimental technique for the characterization of adhesive joints under dynamic multiaxial loadings. The experimental method relies on three main components: i) a conventional split Hopkinson pressure bar (SHPB) apparatus, ii) a novel specimen, denoted as DODECA, which enables testing of three distinct multiaxial loadings using the same method and iii) local strain and stress measurements performed by digital image correlation (DIC). The stress and strain in the adhesive joint are estimated directly from the experimental data both during loading and at the failure point. Another approach based on the Finite Element Model Updating method (FEMU) has been used to complete the adhesive joint model. A numerical inverse method has been developed to obtain elastic, plastic and fracture parameters. Besides, qualitative tools have been proposed to estimate uncertainties on identified parameters. This work has proven the value of local high-speed imaging to characterize adhesive joints.This innovative method has been validated on another specimen denoted as BIADH45. This last study has also emphasized new research interests : in particular, the role of the interfaces in the adhesive joint failure and the benefit of substrates in CMO in dynamic characterization of adhesive joints.

An experimental technique for conducting low speed impact of adhesively bonded automotive composite joints is presented. Based on the use of a modified drop tower, mode I, II, and mixed mode values for critical energy release rate were determined for a composite/epoxy system and used to create a fracture failure envelope. Because load measurements become erratic and unreliable at higher test rates, displacement-based relationships were used to quantify these energy release rates. Displacement data was collected with an imaging system that utilized edge detection to determine displacement profiles, end displacements, and opening displacements where applicable. Because of the resolution of the image-based approach used, determining crack length experimentally was extremely difficult. As a result, numerical methods were developed to objectively determine the crack length based on the available experimental data in mode I, II, and mixed mode I/II configurations. This numerical method uses a nonlinear fit to determine mode I crack lengths and a theoretical model based on cubic equations for mode II and mixed-mode I/II, where the coefficients of the equations are determined by using both boundary and transition conditions that are a result of the test setup. A double cantilever beam (DCB) geometry was chosen to collect mode I data, an end-loaded split (ELS) geometry was used for mode II, and a single leg bend (SLB) geometry was used for mixed-mode I/II. These geometries were used to determine the fracture characteristics of adhesively bonded automotive composites to create fracture failure envelopes as well as provide mode I, II, and mixed-mode I/II data to be used in finite element models. The chosen adhesive exhibited unstable, stick-slip crack growth, which resulted in very few data points being collected from each static DCB specimen as well as drastic drops in energy release rate between initiation and arrest points. Unstable growth also created issues in dynamic testing, as data points surrounding these "stick-slip" events were lost due to the insufficient sampling rate of the available imaging system. Issues also arose with differences between thick and thin composite adherend specimens. These differences could result from additional curing in thick adherend composite specimens due to the adherends retaining heat. DSC testing was conducted on uncured adhesive using a 2, 5, and 10 minute hold at the cure temperature, and significant additional curing was observed between the two and five minute cures. Due to the difference in relative stiffness between the 12 and 36 ply composite, the local loading rate at the crack tip was lower in the 12 ply adherends, possibly allowing for a larger plastic zone and thus a higher energy release rate. As a result, tests were conducted on 36 ply composite specimens at rates of 1 mm/min and 0.1 mm/min to determine if there were loading rate effects. This testing showed that higher initiation energy relase rates were found at the lower test rate, thus reinforcing the local loading rate theory. Due to issues with plastic deformation in aluminum adherends, mode II and mixed-mode I/II data were collected using only composite adherends. Only one data point was collected per specimen as the crack propagated directly into the composite after initiating from the precrack, thus multiple tests were conducted to collect sufficient data for constructing a failure envelope. Once mode I, II and mixed-mode I/II fracture data was collected, a fracture failure envelope was created. This failure envelope, combined with a predetermined factor of safety, could provide some of the necessary tools for design with this adhesive/composite system. / Master of Science

La maintenance, la réparation et le renforcement de murs en maçonnerie par matériaux composites collés nécessitent le développement de méthodes et techniques d'évaluation de l'aptitude au service et de requalification tant pour leur restauration fonctionnelle que pour leur adaptation à de nouvelles contraintes (évolution du zonage sismique par exemple). Le présent travail de thèse a pour objectif de proposer un outil d'évaluation par calcul de l'état limite ultime de murs en maçonnerie, renforcés par composites collés, chargés dans leur plan.Les travaux effectués concernent la modélisation par homogénéisation de murs en maçonnerie et une campagne expérimentale de caractérisation du transfert de charge entre un renfort en tissu de fibres de carbone et un support en blocs creux de béton par le biais d'un joint de colle. Pour modéliser la résistance des murs maçonnés, nous proposons une loi élastique parfaitement plastique pour le comportement dans le plan d'une maçonnerie constituée de blocs liés par des joints de mortier. Le convexe de plasticité est obtenu par une technique d'homogénéisation périodique qui prend en compte la nature tridimensionnelle de la cellule de base. On obtient alors un convexe limité par plusieurs surfaces de charge. Un algorithme numérique original est ensuite proposé et programmé dans le logiciel aux Eléments Finis ABAQUS. Des simulations numériques utilisant le module développé sont présentées / Maintenance, repair and reinforcing of masonry walls with composite materials glued require the development of methods and techniques for evaluating the suitability for service and retraining for both their functional restoration for their adaptation to new constraints (changes seismic zoning for example). This thesis aims to propose an evaluation tool by calculating the limit state of masonry walls,reinforced bonded composite, loaded in their plane.The work done on modeling by homogenization of masonry walls and acampaign experimental characterization of charge transfer between a reinforcement of carbon fiber fabric and a backing of hollow blocks concrete by means of an adhesive joint. To model the resistance of masonry walls, we propose a law for elastic perfectly plastic behavior in the plane formed of masonry blocks connected by mortar joints. The convex plasticity is obtained byperiodic homogenization technique which takes into account the three dimensional nature of the basic cell. This gives a convex bounded by several surfaces of charge. An algorithm digital original is then proposed and programmed in the finite element software ABAQUS. Numerical simulations using the developed module are presented

The first part of the diploma thesis with name „Hybrid adhesive bonded joints of metals and composite materials“ comprise surface pretreatment review. There is also mentioned current review of adhesives for composite and aluminium adherends. The second part of the thesis is dedicated to lap hybrid joint shear strength tests. The effects of adherend thickness, overlap lenght and surface pretreatment on shear strength were investigated. Measured parameters of hybrid joints are proved with a FE analysis with enough accuracy. Conclusions could be used for optimum design of hybrid joint with aluminium and composite adherends.

L’industrie pétrolière s’intéresse aujourd’hui à la possibilité de remplacer certaines brasures par des joints adhésifs rendus conducteurs par leur fort taux de charges conductrices dans les outils électroniques. Ces outils évoluent aujourd’hui à des hauts niveaux de température et de pression pendant leur vie en service. L’utilisation de joints adhésifs pose donc automatiquement la question de leur fiabilité à long terme. L’étude de leur tenue en fatigue, et de l’influence du vieillissement sur cette tenue en fatigue devient nécessaire pour le déploiement final de ces joints. Cette thèse se propose de répondre à une double question : la prédiction de la durée de vie de deux colles commerciales dans les outils électroniques et l’influence du vieillissement de ces colles sur cette prédiction. Deux vieillissements différents ont été mis en œuvre : un vieillissement à l’air libre et un vieillissement inerte (sous argon) confiné.Dans un premier temps, une caractérisation expérimentale du comportement viscoélastique des colles a été menée. Elle met en particulier l’accent sur les non-linéarités induites par les deux paramètres de chargements retenus que sont le cisaillement et la pression hydrostatique.Dans un deuxième temps, une étude plus fine de la microstructure a été effectuée numériquement. Une série d’hypothèses de modélisation a été faite. Les résultats de ces calculs - plutôt qualitatifs - permettent de dégager les tendances sur l’influence de la présence des charges conductrices sur la réponse macroscopique du joint adhésif.Enfin, la tenue en fatigue des joints et sa dépendance à leur vieillissement a été abordée expérimentalement. L’influence de l’atmosphère et du confinement pendant le vieillissement sur l’évolution de la tenue en fatigue a été mise en évidence pour les deux colles étudiées dans cette thèse. Les résultats obtenus ont permis de proposer des lois de fatigue dont certains paramètres dépendent du vieillissement. / The substitution of soldering by electrically conductive adhesive bonding in electronic assemblies is of growing interest in the oil-and-gas industry. These electronic assemblies should nowadays work at high temperature and pressure levels during their service lives. The question of the long-term reliability of adhesive bonding becomes in this context a critical issue. The study of the fatigue strength of adhesive joints as well as the influence of ageing on this strength is therefore crucial for the final deployment of adhesive bonding. This work aims at addressing this fatigue lifetime prediction for two different commercial adhesives in electronic tools, and studying the influence of ageing on the lifetime prediction. Two types of ageing were implemented: an open-air ageing and a confined inert ageing (under Argon).An experimental characterization of the viscoelastic behavior of the two adhesive joints was first carried out. In particular, the non-linearities due to each of the loading parameter (simple shear and hydrostatic pressure) were highlighted and modeled.The microstructural heterogeneity brought by the metallic conductive fillers was then numerically studied. The numerical model introduces several approximations that make the results qualitative, but they highlight the influence of the fillers on the global macroscopic behavior of the adhesive joint.The question of the fatigue strength of adhesive joints and its evolution with ageing is finally experimentally addressed. The influence of the atmosphere and confinement of ageing on the lifetime prediction is clearly noticed for the two joints studied in this work. Fatigue criteria with some of the parameters evolving this ageing are proposed to fit the results experimentally obtained.

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Pour alléger les véhicules, des structures multi-matériaux utilisant des matériaux composites sont envisagées par les industriels automobiles. Les liaisons sont les points faibles de ces structures. Dans ce travail de thèse, le boulonnage, la fixation par insert et le collage utilisés dans l’assise d’un siège automobile en métal/composite ont été étudiés. Les pièces envisagées de l’assise ont été réalisées en composite tissé (verre/ PA6) et en composite injecté (verre/PA66). Y compris pour les films adhésifs, les lois de comportement ont été établies à partir d’essais expérimentaux. Pour les pièces munies d’un trou et pour la liaison boulonnée, le volume critique déterminant la rupture du composite tissé a été utilisé dans les calculs numériques. Dans le cas du collage, la distance critique déterminant la rupture de l’adhésif a aussi été considérée. Des éprouvettes de simple recouvrement et des triangles collés soumis à la torsion ont été testés et simulés. Pour la rupture d’une pièce en composite injecté à fibres courtes, la résistance mécanique du matériau a été évaluée en fonction de l’orientation locale des fibres. Une bielle en composite injecté a été testée et calculée. Les lois de comportement et les méthodes de prédiction de rupture établies ont été utilisées dans le calcul numérique du siège soumis à l’essai de choc. / To reduce the weight of vehicles, the multi-material structures with composite materials have been used in the automotive industries. However, the joints are considered as the weakest parts of the structure. In this work, the joining methods used for metal/ composite automotive seat, including a mechanical joint, a threaded insert and an adhesive joint, have been studied. The components of the seat under consideration were made of woven composite (glass/PA6) and short fiber composite (glass/PA66). The mechanical behaviors of the studied materials, including adhesives, have been modeled based on the experimental results. For parts containing an open-hole and for mechanical joints, the characteristic volume has been used to determine the failure of woven composite. In the case of adhesive joints, the characteristic length has been used to determine the failure. Single lap shear tests and the torsion tests on a bonded structure were conducted and simulated. For the failure of short fiber composite structure, the material strength has been evaluated as a function of local fiber orientation. The tensile tests on the short fiber composite connecting rod were conducted and simulated. Finally, the proposed constitutive laws and failure prediction methods were applied for the simulation of the automotive seat under crash test condition.