Готові списки джерел за темами / Stratifié composite hybride

Добірка наукової літератури з теми "Stratifié composite hybride"

Автор: Grafiati

Опубліковано: 9 листопада 2023

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Статті в журналах з теми "Stratifié composite hybride"

Bunea, Marina, Radu Bosoanca, Adrian Cojan, and Iulian Gabriel Birsan. "Thermomechanical and Electrical Properties of Fabric Reinforced Laminates with Filled Stratified Epoxy Matrix." Materiale Plastice 55, no. 3 (September 30, 2018): 269–73. http://dx.doi.org/10.37358/mp.18.3.5011.

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The thermal coefficient of linear expansion, the electrical conductivity and dielectric permittivity of fabric reinforced hybrid composites with filled stratified epoxy matrix were investigated. The measurements of electrical conductivity and dielectric permittivity had been performed, using standard method regarding electrical resistance and electrical capacity. In order to point out the effect of filler and of the spatial distribution of reinforcement layers, the medial layer of fabric was especially prepared by introducing copper wires in the woven. So, the medial layer is made of different types of tows (carbon, aramid, glass). This attempt is made in order to design a composite able to provide information about its state during various loading. The results showed that the fillers did not improve the electrical parameters of epoxy matrix, but they led to reduce the thermal coefficient of linear expansion. The thermal and electrical behavior of hybrid composites varied in dependence of number of carbon layers and fiber orientation.

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Stefanescu, Victorita, Ana Boboc, A. Cojan, R. Bosoanca, cristian Muntenita, and Marina Bunea. "The Thermal Behavior of Hybrid Fabric Reinforced Composites with Stratified Filled Epoxy Matrix." Materiale Plastice 55, no. 2 (June 30, 2018): 161–67. http://dx.doi.org/10.37358/mp.18.2.4986.

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In this research, the thermal performance of the hybrid composites with modified epoxy matrix was investigated. The results were compared with those presented by the hybrid composites with homogeneous epoxy matrix. For understand the effects of the replacement of lower specific density glass fabric by higher specific density glass fabric, the thermal properties of the hybrid epoxy composites were determined by comparison to the thermal results of composites reinforced with lower specific density glass fabric with those of the hybrid epoxy materials reinforced with higher specific density glass fabric. Also, the effects on the specific heat and thermal expansion coefficient of the used fabric types in outer sheets of the composites were studied.

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Birsan, Iulian Gabriel, Vasile Bria, Marina Bunea, and Adrian Circiumaru. "An Experimental Investigation of Thermal Properties of Fabric Reinforced Epoxy Composites." Materiale Plastice 57, no. 2 (July 1, 2019): 159–68. http://dx.doi.org/10.37358/mp.20.2.5362.

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Specific heat and thermal linear expansion coefficient of epoxy composites reinforced with carbon, aramid, glass and hybrid fabrics with unfilled and filled stratified matrices were studied. The thermal measurements of specific heat were performed with Differential Scanning Calorimeter (DSC instrument) and those of thermal coefficient of linear expansion were realized with Thermomechanical Analyzer (TMA instrument). It was analyzed the influence of fiber orientation at various angles (�15�, �30� and �45�) and the effects of two types of filler mixtures added into polymeric matrix on the thermal behavior of composite materials. It was found that in case of epoxy matrix the added filler mixtures reduced its thermal coefficient of linear expansion and had an insignificant influence on specific heat. In case of epoxy composites reinforced with fabrics, the fiber orientation and fillers addition showed different effects on the investigated thermal parameters in dependence of the used reinforcement types.

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Bunea, Marina, Iulian Gabriel Birsan, and Adrian Circiumaru. "An Experimental Study on the Low Velocity Impact Behavior of Hybrid Epoxy Composites." Materiale Plastice 57, no. 2 (July 1, 2019): 179–90. http://dx.doi.org/10.37358/mp.20.2.5364.

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The low velocity impact response of hybrid epoxy composites reinforced with plain weave fabrics, ply orientation at various angles and filled stratified matrix was analyzed in this study. The hybrid epoxy composites were subjected to impact tests at 45J and 90J of energy levels with drop weight impact machine. The damaged areas were investigated by visual inspection of impacted and non-impacted surfaces and by tomographic images. It was found that the replacement of certain carbon inner plies with glass ones and the modification of fiber orientation improved the damage resistance of the hybrid composites with aramid outer layers subjected to impact loading at 45J of energy level.

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Szymańska, Jowita, Mohamed Bakar, Anita Białkowska, and Marcin Kostrzewa. "Study on the adhesive properties of reactive liquid rubber toughened epoxy-clay hybrid nanocomposites." Journal of Polymer Engineering 38, no. 3 (March 28, 2018): 231–38. http://dx.doi.org/10.1515/polyeng-2017-0099.

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AbstractThe present work investigates the adhesive properties and morphology of diglycidyl ether of bisphenol A nanocomposites modified with reactive butadiene acrylonitrile copolymers having different amine equivalent weight. Tensile adhesive strength and shear adhesive strength of epoxy resin were significantly increased due to reactive rubbers and nanoparticles (ZW1) incorporation to the epoxy matrix. Hybrid composites based on 1 wt% ZW1 and 10 wt% ATBN-16, 1 wt% ZW1 and 15 wt% ATBN-21 exhibited maximum adhesive strength in comparison with neat epoxy resin as well as epoxy nanocomposite containing 1% ZW1. Tensile adhesive strength of hybrid composites containing 1% ZW1 and 10% ATBN-16 as well as 1% ZW1 and 15% ATBN-21 was maximally enhanced. The fracture surfaces of epoxy hybrid composites showed significant plastic yielding together with delaminated and stratified structures, explaining thus the increase of the adhesive strength of tested composites. This finding was confirmed by FTIR spectra in terms of chemical reactions occurrence between the reactive rubbers and epoxy matrix.

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Bunea, M., A. Cîrciumaru, M. Buciumeanu, I. G. Bîrsan, and F. S. Silva. "Low velocity impact response of fabric reinforced hybrid composites with stratified filled epoxy matrix." Composites Science and Technology 169 (January 2019): 242–48. http://dx.doi.org/10.1016/j.compscitech.2018.11.024.

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Szymańska, Jowita, Mohamed Bakar, Marcin Kostrzewa, and Marino Lavorgna. "Preparation and characterization of reactive liquid rubbers toughened epoxy-clay hybrid nanocomposites." Journal of Polymer Engineering 36, no. 1 (January 1, 2016): 43–52. http://dx.doi.org/10.1515/polyeng-2014-0393.

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Abstract The present work investigates the effect of organomodified nanoclay (ZW1) and butadiene-acrylonitrile copolymer terminated with different amine groups (amine-terminated butadiene-acrylonitrile, ATBN) on the properties and morphology of epoxy resin. The morphologies of the nanocomposites were analyzed by X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The nanocomposites structure was confirmed by Fourier transform infrared (FTIR) spectroscopy, XRD and TEM. The properties evaluation showed that the polymeric modifier and nanoclays strongly influence the fracture toughness and flexural properties of the nanocomposites. Hybrid epoxy composites containing 1% ZW1 and ATBN rubbers showed improved fracture toughness and flexural properties in comparison with unmodified epoxy resin. FTIR spectra showed an increase in the hydroxyl peak height peak height of 3360 cm-1 due to reactive rubber incorporation. SEM micrographs of hybrid epoxy resin nanocomposites showed significant plastic yielding of the polymer matrix with stratified structures and more cavitations, explaining thus the enhancement of fracture toughness and flexural strength of the nanocomposites.

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Jyani, Gaurav, Shankar Prinja, Sitanshu Sekhar Kar, Mayur Trivedi, Binod Patro, Fredrick Purba, Star Pala, et al. "Valuing health-related quality of life among the Indian population: a protocol for the Development of an EQ-5D Value set for India using an Extended design (DEVINE) Study." BMJ Open 10, no. 11 (November 2020): e039517. http://dx.doi.org/10.1136/bmjopen-2020-039517.

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IntroductionQuality-adjusted life year (QALY) has been recommended by the government as preferred outcome measure for Health Technology Assessment (HTA) in India. As country-specific health-related quality of life tariff values are essential for accurate measurement of QALYs, the government of India has commissioned the present study. The aim of this paper is to describe the methods for the Development of an EQ-5D Value set for India using an Extended design (DEVINE) Study. Additionally, this study aspires to establish if the design of 10-time trade-off (TTO) blocks is enough to generate valid value sets.Methods and analysisA cross-sectional survey using the EuroQol Group’s Valuation Technology (EQ-VT) will be undertaken in a sample of 2700 respondents selected from six different states of India using a multistage stratified random sampling technique. The participants will be interviewed using computer-assisted personal interviewing technique. The TTO valuation will be done using 10 composite TTO (c-TTO) tasks and 7 discrete choice experiment (DCE) tasks. Hybrid modelling approach using both c-TTO and DCE data to estimate the potential value set will be applied. Values of all 3125 health states will be predicted using both the conventional EQ-VT design of 10 blocks of 10 TTO tasks, and an extended design of 18 blocks of 10 TTO tasks. The potential added value of the eight additional blocks in overall validity will be tested. The study will deliver value set for India and assess the adequacy of existing 10-blocks design to be able to correctly predict the values of all 3125 health states.Ethics and disseminationThe ethical approval has been obtained from Institutional Ethics Committee of PGIMER, Chandigarh, India. The anonymised EQ-5D-5L value set will be available for general use and in the HTAs commissioned by India’s central HTA Agency.

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Perez Beltran, Saul, and Perla B. Balbuena. "Lithium Dissolution and SEI Formation on Lithium Metal Anodes: Electrolyte and Surface Effects." ECS Meeting Abstracts MA2022-02, no. 2 (October 9, 2022): 145. http://dx.doi.org/10.1149/ma2022-022145mtgabs.

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The lithium metal battery (LMB) rises as one of the most promising energy storage alternatives primarily due to the lithium metal’s high theoretical specific capacity (3860 mAh/g vs. 372 mAh/g for graphite) and high achievable operation voltage [1, 2]. However, and regardless of the coupling cathode electrode, one of the main challenges before the practical application of LMBs comes down to engineering electrolyte formulations compatible with lithium metal to eliminate dendrite formation and the uncontrolled loss of electrolyte and active lithium by forming a robust, ionic-conductive, and electron insulating, solid electrolyte interphase (SEI). Any improvement of the electrolyte/lithium metal interface passes through a thorough understanding of the reaction mechanisms behind the electrolyte degradation and the subsequence formation of the SEI. Characterizing this interface via experimental techniques is a challenge because of its delicate nature and simultaneous presence of liquid and solid phases. Here, we successfully narrowed this gap via computational modeling by using a recently introduced hybrid ab initio and reactive molecular dynamics (HAIR) scheme that uses in sequence the ab-initio molecular dynamics (AIMD) and the reactive force field (ReaxFF) methods to extend the time window achievable with the AIMD method alone. We performed a series of HAIR calculations with multiple electrolytes formulations on a lithium metal slab (Li(100)) with varying electrolyte/anode (E/A) ratios to evaluate the impact of the lithium salt concentration, type of solvent, presence of a diluent, and lithium thickness on the rate of electrolyte depletion, lithium dissolution, and SEI morphology. It is found that increasing salt concentration in a LiFSI/DMC electrolyte from 1 to 5 and then to 10 M yields significant changes in SEI morphology. The 1 M electrolyte led to DMC degradation into -O-CH3 with no significant LiO formation. In contrast, the 5 and 10 M formulations evolved into an SEI structure dominated by continuous and stratified LiO and LiF phases. Changes in the SEI morphology based on the E/A ratio for the 10 M LiFSI/DMC electrolyte revealed the existence of an intermediate E/A ratio leading to a more compact and more inorganic-rich SEI; the formed LiO phase density was higher than that in other ensembles representative of dry and flooded electrolyte operation conditions. Our third set of calculations focused on the effect of solvent chemistry. The 5 M LiFSI/DME electrolyte led to the formation of a LiO phase surrounded by some residual DME solvent; in this wetted SEI, the residual solvent provides diffusion channels for Li+ ions. Finally, we tested the impact of adding 1,1,2,2-tetrafluoroethylene 2,2,3,3-tetrafluoropropyl ether (TTE) as a diluent into the electrolyte using a 1.3 M LIFSI:DMC:TTE (1:1.2:3 molar ratio) formulation. The TTE diluent showed decomposition and helped grow a LiF-dominated SEI film with a lower LiO/LiF phase ratio than the equivalent 5.0 M LiFSI/DMC formulation with no electrolyte. These results form the basis for a deeper understanding of the SEI formation mechanisms and provide a design guideline for SEI films based on the lithium salt concentration, relative electrolyte/electrode content, and presence of a diluent. References: 1. Asenbauer, J., et al., The Success Story of Graphite as a Lithium-Ion Anode Material – Fundamentals, Remaining Challenges, and Recent Developments Including Silicon (Oxide) Composites. Sustainable Energy & Fuels, 2020. 4(11): p. 5387-5416. 2. Liu, B., J.-G. Zhang, and W. Xu, Advancing Lithium Metal Batteries. Joule, 2018. 2(5): p. 833-845.

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Birk, Manjot, Vivien Chan, Nicholas J. Yee, Evan Dimentberg, Jessica Wenghofer, Matias Pereira Duarte, Tara Gholamian, et al. "Canadian Spine SocietyCPSS-1. Abstract ID 108. Radiographic reporting in adolescent idiopathic scoliosis: Is there a discrepancy between radiologists’ reports and surgeons’ assessments?CPSS-2. Abstract ID 21. Pediatric posterior spinal deformity correction: 30-day postoperative infection rate and risk factorsCPSS-3. Abstract ID 17. “Ultra-low dose” computed tomography without sedation is feasible and should be considered as part of the preoperative optimization pathway in paediatric patients with neuromuscular scoliosisCPSS-4. Abstract ID 20. SeeSpine: a novel surface topography smartphone application for monitoring curve progression in adolescent idiopathic scoliosisCPSS-5. Abstract ID 78. Pilot study: a machine learning algorithm for the detection of adolescent idiopathic scoliosis from images taken with modern smartphone technologyCPSS-6. Abstract ID 101. 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Automatic extraction of spinopelvic parameters using artificial intelligence methods and a review on the effects of spine stiffness, spinal fusion and spinopelvic parameters on lower limb motion and total hip arthroplasty outcomesA-19. Abstract ID 38. Gender differences in fusion rates in the treatment of degenerative lumbar spondylolisthesis: analysis from the CSORN prospective degenerative lumbar spondylolisthesis studyA-20. Abstract ID 29. L3–4 hyperlordosis after a reduction in lower lumbar lordosis with L4–L5 fusion surgery is common in patients requiring L3–4 revision surgery for adjacent segment diseaseB-21. Abstract ID 40. Predictors of dynamic instability in the decision to fuse in degenerative lumbar spondylolisthesis: results from the Canadian Spine Outcomes and Research Network prospective degenerative lumbar spondylolisthesisstudyB-22. Abstract ID 49. Impact of preoperative insomnia on poor postoperative pain control after elective spine surgery and the Modified Calgary Postoperative Pain After Spine Surgery scoreB-23. Abstract ID 115. Influence of high pelvic incidence on operative difficulty in patients treated surgically for degenerative lumbar spondylolisthesisB-24. Abstract ID 45. Reoperation rates for adjacent segment disease in degenerative lumbar fusion surgery: a comparison between minimally invasive versus open surgical approachesB-25. Abstract ID 118. Assessment of changes in opioid utilization 1 year after elective spine surgery: a Canadian Spine Outcomes and Research Network studyB-26. Abstract ID 93. Preoperative neuroleptic and opioid use effects on postoperative pain and disability after spinal surgery for lumbar radiculopathyB-27. Abstract ID 52. The importance of lower extremity compensation mechanisms in lumbar degenerative pathology: a retrospective analysisB-28. Abstract ID 107. 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Earlier tracheostomy reduces complications in complete cervical spinal cord injury in real-world practice: analysis of a multicentre cohort of 2001 patientsD-42. Abstract ID 87. Neuroprotection after traumatic spinal cord injury through mitochondrial calcium uniporter inhibitionD-43. Abstract ID 16. The impact of specialized versus nonspecialized acute hospital care on survival among patients with acute incomplete traumatic spinal cord injuries: a population-based observational study from British Columbia, CanadaD-44. Abstract ID 59. Stem cells from human spinal cord exhibit reduced oligodendrogenesis compared with rodent stem cellsD-45. Abstract ID 122. Harnessing the endogenous stem cell response after spinal cord injuryD-46. Abstract ID 62. Comparison of age and 5-Item Modified Frailty Index as predictors of in-hospital mortality for patients with complete traumatic cervical spinal cord injuryD-47. Abstract ID 109. Unplanned readmissions after traumatic spinal cord injury: perspective from the British Columbian populationD-48. Abstract ID 9. The radiographic characteristics that lead surgeons to agree and disagree on making treatment recommendations in thoracolumbar burst fractures without neurologic deficitsD-49. Abstract ID 19. The effect of Enhanced Recovery After Surgery protocols for elective cervical and lumbar spine procedures on hospital length of stay: a systematic review and meta-analysisD-50. Abstract ID 23. Exploring end-of-life decision-making and perspectives on medical assistance in dying through the eyes of individuals living with cervical spinal cord injuries in Nova ScotiaE-51. Abstract ID 88. Neurologically intact thoracolumbar burst fractures (AO Spine A3, A4) improve on Oswestry Disability Index equally when treated surgically versus nonoperativelyE-52. Abstract ID 28. Predictive algorithm for surgery recommendation in thoracolumbar burst fractures without neurological deficitsE-53. Abstract ID 36. A randomized trial of cervical orthosis versus no orthosis after multilevel posterior cervical fusionE-54. Abstract ID 11. Deterioration after surgery for degenerative cervical myelopathy: an observational study from the Canadian Spine Outcomes and Research NetworkE-55. Abstract ID 66. Canadian cohort of older patients with cervical spinal cord injury: Do radiologic parameters correlate with initial neurological impairment?E-56. Abstract ID 6. Surgical complications or neurologic decline? A patient discrete-choice experiment for cervical myelopathyE-57. Abstract ID 82. Laminectomy alone for cervical spondylotic myelopathy: a Canadian Spine Outcomes and Research Network StudyE-58. Abstract ID 95. The effect of surgical approach on patient outcomes of degenerative cervical myelopathy: a pooled analysis of individual patient data from 1031 casesE-59. 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Variability in treatment of adult spinal deformity, a Canadian surveyP-105. Abstract ID 83. Anterior cervical hybrid constructs reduce upper adjacent segment hypermobility compared with anterior cervical discectomy and fusionP-106. Abstract ID 48. A preliminary report of robotic screw insertion in cadaveric vertebrae using the Mazor X systemP-107. Abstract ID 54. Invasive brain–computer interface for motor restoration in spinal cord injury: a systematic reviewP-108. Abstract ID 27. A new cost-effective technique to mimic pedicle screw trajectory in cadavers: a robotic validation studyP-109. Abstract ID 14. Developments and applications of augmented and virtual reality technology in spine surgery training: a systematic reviewP-110. Abstract ID 80. Comprehensive accuracy analysis of robotic models in spine surgery: a pooled analysis of 14 462 screwsP-111. Abstract ID 99. Familial chiari malformation: a systematic reviewP-112. Abstract ID 31. Ninety-day complication and revision surgery rates using navigated robotics in thoracolumbar spine surgeryP-113. Abstract ID 111. Which baseline clinical factors and clinical indications are most correlated with outcome after lumbar fusion surgery?P-114. Abstract ID 92. Characterization of the mechanical state of human mesenchymal stem cells on micro- or nano-textured Ti6Al4V surfacesP-115. Abstract ID 72. Short-term outcomes associated with the use of macro–micro–nano rough Ti6Al4V (nanoLOCK) interbody cages in patients with lumbar spine degenerative conditionsP-116. Abstract ID 127. Introduction of a novel concept to decompress foramen magnum in chiari-1 malformation without affecting stabilityP-117. Abstract ID 57. Minimally invasive tubular lumbar decompression without fusion in lumbar stenosis with underlying deformity: Friend or foe?P-118. Abstract ID 64. The role of intraoperative ultrasound in nononcological intradural lumbar spine conditions: intradural lumbar disc herniation and subdural spinal abscessP-119. Abstract ID 120. Prospective Prophylactic Antibiotics Regimen in Spine Surgery: the PPARiSS cohortP-121. Abstract ID 70. Decompression versus decompression and fusion in cauda equina syndrome secondary to massive lumbar disc herniationP-122. Abstract ID 105. Implementation of robot-assisted surgery for elective spine surgeryP-123. Abstract ID 37. Spine surgery in patients with morbid obesity: tips and tricksP98: Abstract ID 71. Pelvic incidence is associated with reoperation for adjacent segment disease in degenerative lumbar spinal fusion surgery." Canadian Journal of Surgery 66, no. 4 Suppl 1 (August 11, 2023): S1—S53. http://dx.doi.org/10.1503/cjs.006523.

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Дисертації з теми "Stratifié composite hybride"

Dubary, Nicolas. "Optimisation numérique et expérimentale de la tolérance aux dommages d’impact d’un stratifié composite aéronautique." Electronic Thesis or Diss., Toulouse, ISAE, 2017. http://www.theses.fr/2017ESAE0038.

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Dans un souci majoritaire de gain en masse et pour l’intégration de solutions innovantes et de structures hautes performances dans les applications actuelles, les matériaux composites occupent une place grandissante au sein des structures aéronefs. Cependant, ils restent vulnérables aux sollicitations hors-plan tel que l’impact, dues par exemple à une chute d’objet pendant une opération de maintenance. Cet événement peut drastiquement réduire leur tenue résiduelle sans pour autant laisser de marque visible en surface. Pour répondre aux exigences réglementaires et permettre une utilisation saine en service, les structures composites sont donc souvent surdimensionnées.Ces travaux de thèse portent sur l’étude expérimentale et numérique de la tolérance aux dommages d’impact (TDI) d’un stratifié composite aéronautique. Entre méthodologie et technique, le thème de recherche propose une étude complète de l’intégrité d’une structure composite, permettant l’apport de connaissances ainsi qu’une compréhension approfondie de la TDI.Le dimensionnement des structures composites s’appuie sur les méthodes aéronautiques d’inspection visuelle des endommagements définissant les charges acceptables et requises par la structure. En effet, la détectabilité de l’endommagement permet une intervention de réparation sur la structure : tant que l’endommagement n’est pas détecté (BVID : Barely Visible Impact Damage), les performances de la structure doivent rester élevées. De nouveaux concepts de stratifiés composites hybrides sont proposés puis testés expérimentalement dans le but d’améliorer la TDI et d’approfondir également la connaissance du comportement des stratifiés composites. Ces concepts sont établis à partir d’un cas de référence, ensuite décliné sous différentes configurations de stratifiés composites hybrides. La démarche expérimentale de la TDI est alors menée depuis l’impact jusqu’à la compression après impact pour définir les deux indicateurs principaux de cette étude : l’indentation permanente et la tenue résiduelle.En parallèle, le modèle développé à l’ICA, le Discret Ply Model (DPM), est utilisé pour proposer une démarche de dimensionnement de stratifié intégrant la philosophie de la TDI. Des améliorations de modélisation et son extension aux stratifiés composites hybrides sont ensuite proposées. Elles ouvrent sur l’utilisation du DPM comme un outil d’aide au dimensionnement des structures composites. Cette démarche est en parfaite cohérence avec l’intégration des approches numériques pour assister les études expérimentales, s’intégrant dans le cadre du « Virtual Testing »
Coupling with will of mass gain, use of innovative solutions and high performance structures in today’s industrial applications, composites are more and more present in aeronautical structures. However, they are still vulnerable to out-of-plane loading such as impact, due to falling objects during a maintenance operation for instance. This event can drastically reduce their residual strength without let a visible mark onto the surface. Therefore in order to meet requirements and drive to healthy use in service, composites structures are often oversized.This work deals with the experimental and numerical study of the Impact Damage Tolerance (IDT) of an aeronautical composite laminate. An overall study of composite structures integrity leads to a deeper knowledge of the IDT.The approach is based on aeronautical methods for the damages visual inspection: the damage detectability defines the required load that the structure has to sustain. Indeed, the detectability of the damage allows a repair intervention on the structure: as long as the damage is not detectable (BVID), the performance of the structure must remain high. Proposed concepts are experimentally tested to improve the TDI and to bring to more understanding in the behavior of composite laminates. These concepts are based on a reference case, and then declined under different configurations of hybrid composite laminates. The experimental approach of TDI is carried out from impact to compression after impact to define the two main indicators: permanent indentation and residual strength.The model developed at ICA, the Discrete Ply Model (DPM), is used to propose a numerical designing approach according to the TDI philosophy. Modeling improvements are implemented to extend to hybrid composite laminates. This step opens up on the use of DPM as a tool to assist the composite structures sizing. This advanced is in respect with the integration of numerical approaches to support experimental studies, integrating within the framework of "Virtual Testing"

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Mahmoud, Bassam. "Modélisation d'impacts sur des stratifiés composites unidirectionnels et hybrides." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30212.

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Les structures aéronautiques sont aujourd’hui largement réalisées à partir de matériaux composites, permettant ainsi d’en diminuer la masse. L’impact sur structure composite est une des sources de dommage la plus courante et la plus pénalisante. L’objectif de cette thèse est de développer un modèle prédictif d’impact sur stratifiés unidirectionnels de faible épaisseur afin, dans un premier temps, de mieux comprendre les mécanismes d’endommagement mis en jeu et, dans un deuxième temps, de pouvoir proposer des pistes d’amélioration de la tenue de ces structures. La première étape de ces travaux a consisté à développer un modèle éléments finis explicite de stratifiés composite unidirectionnel, en s’appuyant sur les travaux d’impact sur pale d’hélicoptère réalisés par F. Pascal. Ainsi, un nouvel élément capable de représenter le comportement à l’impact des plis unidirectionnels a été formulé. Le comportement des paquets de fibres est représenté par des éléments barres stabilisés grâce à des éléments 2D spécifiques. La dégradation de ces éléments est pilotée par des lois d’endommagement déduites d’observations expérimentales. La stratégie de modélisation proposée a été identifiée sur la base d’essais expérimentaux pour deux matériaux : T700/M21 et HTA7/913. Les résultats donnés par le modèle ont ensuite été validés par une comparaison avec des essais d’impact à basse vitesse. Enfin, dans le but d’optimiser la tenue des stratifiés, des impacts à basse et moyenne vitesse sur des stratifiés hybrides unidirectionnels/tissus composites ont été étudiés expérimentalement et numériquement grâce à la stratégie de modélisation proposée
Today, composite materials are largely used in the manufacturing of aeronautical structures, in order to lighten their weight. Impact on composite structures is one of the most detrimental loading. The present study aims to develop a predictive modelling of impacts on thin unidirectional laminates in order to, firstly, better understand the damage mechanisms involved, and, secondly, be able to provide guidance for a strength improvement of these structures. First, an explicit finite element modelling of unidirectional laminates is developed based on the work of F Pascal dealing with impact modeling on helicopter blades. Thus, a new element that can represent the impact response of unidirectional plies is formulated. The behavior of the bundle of fibers is modeled with rod elements stabilized with specific 2D elements. The degradation is managed using damage based on experimental observations. The parameters of the proposed modelling strategy are identified on the basis of experimental tests carried out on T700/M21 and HTA7/913 composites. The results provided by the modeling are then validated by a comparison with experimental low velocity impact results. Finally, in order to improve the laminate strength, low velocity and medium velocity impacts on hybrid unidirectional/woven composite laminates are studied experimentally and with the developed modelling strategy

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Miot, Stéphanie. "Rupture de structures composites stratifiées sous chargements statique et de fatigue." Aix-Marseille 1, 2009. http://www.theses.fr/2009AIX11016.

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L’utilisation des matériaux composites est en plein essor depuis quelques années, notamment dans le secteur aéronautique. C’est dans le cadre d’un partenariat avec Eurocopter que s’inscrivent ces travaux de thèse visant à analyser expérimentalement et à modéliser le comportement jusqu’à rupture de structures composites stratifiées sous chargements statique et de fatigue. Pour décrire le comportement mécanique des matériaux composites, plusieurs mécanismes de dégradation sont à considérer. Un modèle, basé sur la Mécanique de l’Endommagement, a récemment été développé au LMA. Il traduit les effets des endommagements transverse et de cisaillement, se caractérisant par la formation de petites fissures évoluant le long des fibres. Ce modèle a été intégré dans le code de calcul Abaqus/Standard afin d’étudier le comportement de structures stratifiées soumises à un chargement statique ou de fatigue. Les comparaisons essais / simulation ayant mis en évidence le fait que les critères de rupture classiques ne fonctionnent pas si le champ de déformation n’est pas homogène, une approche non locale a été développé. Basée sur un Volume Caractéristique de Rupture, elle permet de prendre en compte l’effet des concentrations de contraintes pour décrire la rupture de structures stratifiées. Une confrontation expérimentale a permis de valider le modèle de comportement associé à l’approche non locale pour divers matériaux, stratifiés et géométries pour des cas de chargements statiques. L’application aux cas de chargements de fatigue est encore à l’étude. Toutefois, les premières comparaisons entre les résultats de simulations et les essais sont encourageants
Recent developments in the aeronautics industry have accelerated interest in the use of composites as primary structural materials. This project is based on a collaboration with Eurocopter. The objectives are to experimentally analyse and model the behaviour until failure of laminated composite structures under static and fatigue loadings. To describe the mechanical behaviour of composite materials, several damage mechanisms have to be considered. A model, based on the Continuum Damage Mechanics and recently developed at the LMA, takes into account the effects of transverse and shear damages characterized by the creation of small cracks which run along the fibres. This model was integrated into Abaqus/Standard in order to study the behaviour of laminated structures under static and fatigue loadings. The comparisons between experimental data and numerical simulations have proved that conventional failure criteria do not work if the strain field is inhomogeneous. A non local approach, based on the definition of a Fracture Characteristic Volume, has been developed. This method takes into account the effects of stress concentrations on the failure of laminated structures. Comparisons with experimental data allows to valid thebehaviour model associated to the non local approach for various materials, laminates and geometries in the case of static loading conditions. The application in the case of fatigue loading is in progress and first results are promising

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Manseri, Ldjoudi. "Développement d'une stratégie d'endommagement intra/interlaminaire pour une approche semi-continue : application aux stratifiés unidirectionnels et hybrides." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30259.

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Les structures composites constituées de nappes d'unidirectionnels sont très répandues en aéronautique pour leur très grand rapport résistance/masse. Cependant, elles sont susceptibles d'être soumises à une multitude d'impacts qui génèrent des fissurations matricielles, des délaminages et des ruptures de fibres. Cela est très préjudiciable lors d'impacts à basse vitesse notamment sur des structures épaisses où les délaminages sont localisés à l'intérieur donc difficilement de´tectables à l'œil nu. L'objectif est donc de proposer un modèle capable de capter très précisément l'initiation et la propagation des délaminages en se fondant sur la stratégie Semi-Continue. Ces travaux débutent par le développement d'un nouvel élément d'interface intralaminaire pour capter le comportement des fissurations matricielles, précurseuses des délaminages. Cet élément vient s'intercaler entre les éléments UD (barres + plaque) de la stratégie Semi-Continue développés lors de précédents travaux. Afin de représenter le lien entre fissurations matricielles et délaminage, un couplage intra/interlaminaire est introduit. L'ajout de cet élément spécifique a nécessité d'adapter le comportement des autres éléments du modèle afin que la cinématique globale soit conforme aux résultats expérimentaux. Cette stratégie a ensuite été valideé à travers une campagne d'essais d'indentations quasi-statiques et d'impacts à différentes énergies. Les résultats numériques obtenus corrèlent de manière très satisfaisante ceux des essais. Enfin, une campagne d'essais sur stratifiés hybrides (UD/Tissu) a été effectuée d'une part pour optimiser la réponse des structures épaisses et d'autre part pour évaluer la réponse du modèle dans des situations hors de sa zone de validation
Composite structures composed by unidirectional layers are widespread in the aeronautical field for their very high strength to mass ratio. However, they may undergo impacts that can generate matrix cracking, delamination and fiber breakage. This has an adverse effect during low velocity impacts, especially on thick structures where delaminations, are located inside the structure and are difficult to detect with the naked eye. The objective is then to propose a model able to catch very precisely the initiation and the propagation of delamination based on the Semi-Continuous strategy. This work begins with the development of a new intralaminar interface element able to get the behavior of matrix cracking, precursor of delamination. This element is inserted between UD elements (rods + shell) of the Semi-Continuous strategy developed in previous works. In order to represent the link between matrix cracking and delamination, a intra/interlaminar coupling is introduced. The addition of this specific element required to adapt the behavior of other elements of the model so that the overall kinematics would be consistent with experimental results. This strategy was validated through quasi-static indentation and impact tests at different energies. The numerical results obtained correlate very satisfactorily with those of the tests. Finally, tests on hybrid laminates (UD/Woven) were carried out on the one hand to optimize the response of thick structures and on the other hand to evaluate the response of the model in situations outside its validation area

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Hussain, Muzzamal. "Couplage procédé / propriétés mécaniques des matériaux sandwiches Métal / Composite hybride à base de tissus en jute." Thesis, Lille, 2021. http://www.theses.fr/2021LILUI006.

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Dans cette étude, les propriétés mécaniques des FML renforcés de jute tissé 3D et hybrides de jute tissé 3D renforcé ont été étudiées. Le renfort tissé 3D à quatre couches a été fabriqué avec du fil de jute en utilisant quatre types de motifs imbriqués, par ex. Orthogonal Through Thickness OTT et Orthogonal Layer to Layer OLL imbriqué. La technique d'infusion sous vide a été utilisée pour la fabrication de FML avec renfort en jute tissé 3D. Après l'optimisation du renforcement tissé 3D, les FML renforcés hybrides ont été développés dans lesquels le tissu tissé OTT 3D a été pris en sandwich entre une peau tissée 2D. Quatre types de fibres différents ont été utilisés pour fabriquer une peau tissée 2D, par ex. jute, aramide, carbone et verre tandis que trois types différents de matrice ont été utilisés, par ex. époxy, PVB et PP. La presse à chaud par compression a été utilisée pour développer des FML hybrides renforcés. L'aluminium utilisé pour fabriquer tous les FML a été anodisé avant d'être utilisé pour la fabrication. Les propriétés adhésives ont été étudiées pour vérifier la qualité du traitement de surface, la liaison métal-composites et l'effet des fibres et de la matrice. Les propriétés monotones et dynamiques ont également été étudiées. Les propriétés adhésives ont été caractérisées à l'aide de tests de pelage en T et de pelage au rouleau flottant. Les propriétés monotones ont été analysées à l'aide d'essais de traction et de flexion. Les performances d'impact à faible vitesse ont été déterminées en utilisant un test d'impact à faible vitesse. Les résultats ont montré que la surface en aluminium anodisé avait une énergie libre de surface élevée, de sorte que le meilleur mouillage de l'aluminium peut être obtenu par anodisation par rapport à d'autres types de préparations de surface. Les résultats de l'analyse du collage ont montré que les propriétés de délaminage étaient principalement influencées par la nature du matériau adhésif plutôt que par le type de structures de renforcement. La nature de la matrice influence également le type de défaillance car avec l'époxy, la défaillance dominante était cohésive tandis qu'avec la matrice thermoplastique, elle s'est transformée en défaillance adhésive et intra-laminaire. La plasticité et la ductilité de la matrice ont plus influencé les propriétés finales que le type de rupture, malgré la rupture cohésive de l'époxy, la matrice thermoplastique avait plus de force de délamination. Les propriétés de traction et de flexion des FML renforcées de jute tissé OTT 3D étaient supérieures à celles des FML renforcées tissées OLL 3D en raison de la fraction de volume de métal plus élevée, ce qui était possible grâce à une construction plus serrée du tissu OTT. Les propriétés de traction et de flexion des composites hybrides renforcés et des FML ont été influencées par le type de matrice et le matériau de la peau 2D. Les propriétés globales plus élevées ont été obtenues avec une matrice époxy suivie d'une matrice PVB. Les FML à base de PVB ont montré que leurs propriétés étaient comparables à celles de l'époxy. Le test de flexion a montré que les FML hybrides à base de PP échouaient prématurément en raison d'une délamination entre la peau synthétique et l'âme tissée 3D. L'époxy et le PVB ont montré une meilleure imprégnation du renfort contrairement au PP dans lequel seul un verrouillage mécanique a été observé. Les propriétés d'impact dynamique des composites hybrides et des FML ont montré que les caractéristiques de dissipation d'énergie étaient influencées par la matrice et l'hybridation du renforcement
In current study the mechanical properties of 3D woven jute reinforced and hybrid 3D woven jute reinforced FMLs were investigated. The four-layered 3D woven reinforcement was made with jute yarn using four types of interlocking patterns e.g. Orthogonal Through Thickness OTT and Orthogonal Layer to Layer OLL interlocking. The vacuum infusion technique was used for the fabrication of FMLs made with 3D woven jute reinforcement. After the optimization of 3D woven reinforcement the hybrid reinforced FMLs were developed in which OTT 3D woven fabric was sandwiched between 2D woven skin. Four different kinds of fibres were used to make 2D woven skin e.g. jute, aramid, carbon, and glass while three different kinds of matrix were employed, e.g. epoxy, PVB and PP. The compression hot press was used to develop hybrid reinforced FMLs. Aluminium used to make all FMLs was anodized before using for fabrication. The adhesive properties were investigated to check the quality of surface treatment, metal-composites bonding and effect of fibres and matrix. Both monotonic and dynamic properties were also investigated. The adhesive properties were characterized using t-peel and floating roller peel tests. The monotonic properties were analyzed using tensile and flexural tests. The low velocity impact performance was determined using drop weight low velocity impact test. The results showed that the anodized aluminium surface had high surface free energy so the better wetting of aluminium can be achieved by anodizing as compared to other type of surface preparations. The adhesive bonding analysis results showed that the delamination properties were mainly influenced by the nature of adhesive material rather than the type of structures of reinforcement. The nature of the matrix also influences the type of failure as with the epoxy the dominant failure was cohesive while with thermoplastic matrix it changed to adhesive and intra-laminar failure. The plasticity and ductility of matrix influenced the final properties more than the type of failure, in spite of cohesive failure of epoxy the thermoplastic matrix had more delamination force. The tensile and flexural properties of OTT 3D woven jute reinforced FMLs were higher than the OLL 3D woven reinforced FMLs due to the higher metal volume fraction, this was possible due to tighter construction of OTT fabric. The tensile and flexural properties of hybrid reinforced composites and FMLs were influenced by the type of matrix and material of 2D skin. The overall higher properties were achieved with an epoxy matrix followed by PVB matrix. The PVB-based FMLs showed that their properties were comparable with the epoxy. The flexural test showed that hybrid FMLs based on PP were failed prematurely due to delamination between synthetic skin and 3D woven core. Both epoxy and PVB showed better impregnation of the reinforcement unlike PP in which only mechanical interlocking was seen. The dynamic impact properties of hybrid composites and FMLs showed that the energy dissipation characteristics were influenced by matrix and hybridization of reinforcement

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Violeau, David. "Une stratégie de calcul pour l'analyse à l'échelle "micro" des endommagements jusqu'à rupture des composites stratifiés." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2007. http://tel.archives-ouvertes.fr/tel-00254379.

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Les mécanismes de dégradation des composites stratifiés sont aujourd'hui très bien connus mais la simulation jusqu'à rupture reste un challenge majeur. Un nouveau modèle de calcul microscopique hybride a récemment été proposé et permet de prendre en compte tous les modes de dégradations des stratifiés. Le modèle microscopique est hybride et couple à la fois des mécanismes discrets et continus. Celui-ci s'appuie sur l'introduction de surfaces de rupture minimales conférant ainsi au modèle un aspect discret. Un milieu continu endommageable est introduit pour modéliser les dégradations continues à l'échelle du pli. Très simple d'interprétation et reposant sur peu de quantités matériaux à identifier, le modèle n'est viable que s'il est associé à des moyens de calcul performants. Une stratégie multiéchelle avec homogénéisation en espace développée depuis plusieurs années est ici étendue pour traiter des problèmes complexes tridimensionnels et incluant de nombreuses surfaces de contact. Des développements spécifiques associés à la réduction du coût de calcul (taille du problème à résoudre et temps de résolution) ont été menés sur des exemples simples bidimensionnels. Le calcul du critère permettant la propagation des fissures a nécessité également des simplifications importantes. Ces différents points ont été mis en œuvre dans un code de calcul complet écrit en langage C++ dans la plateforme du LMT permettant de traiter des problèmes complexes non-linéaires bidimensionnels ou tridimensionnels et pouvant inclure les effets de l'environnement. Des exemples simples sont réalisés et permettent de simuler des scénarios de dégradation complexes.

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Тези доповідей конференцій з теми "Stratifié composite hybride"

Circiumaru, Adrian, Vasile Bria, Iulian-Gabriel Birsan, Gabriel Andrei, and Dumitru Dima. "Some Properties of Stratified Composites." In ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2010. http://dx.doi.org/10.1115/esda2010-25303.

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The multi-component composites could represent the cheapest solution when controllable properties are required. In order to establish the right amount of filler it is necessary to analyze not only the electro-magnetic and mechanical properties but also, the thermal ones. The filler presence in the matrix produces discontinuities at the fibre-matrix interface with consequences regarding mechanical properties. Using a single filler it is possible to improve one or two properties electrical and thermal conductivity for instance and mean time to induce a decrease of other properties as bending strength, shock resistance etc. Using polymer layers with relatively high electrical conductivity as external layers of laminate and magnetic particles filled polymer as core layers. An electric circuit might be, at the same time, the reinforcement of a composite leading to lighter structures and, based on carbon fiber’s properties might transmit information about the material’s loading, temperature or integrity. Fabric reinforced or textile composites are used in aerospace, automotive, naval and other applications. They are convenient material forms providing adequate stiffness and strength in many structures. The microstructure of composite reinforced with woven, braided, or stitched networks is significantly different from that of tape based laminates. The properties of the composite depend not only on the properties of the components but on quality and nature of the interface between the components and its properties. Reinforced composites with filled epoxy matrix were formed using a hybrid technique consisting in layer-by-layer adding of reinforcement sheets into a glass mould. Various distributions of reinforcement sheets and filled polymer layers were realized in order to point out the ways in which the final properties might be controlled. Mechanical properties were analyzed.

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