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Artigos de revistas sobre o assunto "Embedded fiber model"
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Gu, X., e R. J. Young. "Deformation Micromechanics in Model Carbon Fiber Reinforced Composites Part II: The Microbond Test". Textile Research Journal 67, n.º 2 (fevereiro de 1997): 93–100. http://dx.doi.org/10.1177/004051759706700204.
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Raman spectroscopy is used to study the deformation micromechanics of the microbond test for a carbon fiber epoxy resin system using surface-treated and untreated PAN-based fibers, and the results are compared with those of the conventional microbond test. Fiber strain and interfacial shear stress (ISS) are mapped along the embedded regions of fibers during the test using the Raman technique, and the maximum value of ISS, τmax, is determined. The maximum τmax value can be used to characterize the strength of the fiber matrix interface, and it is higher for specimens with surface-treated fibers. The apparent value of interfacial shear strength, τ a, determined from conventional analysis of the microbond test, is a function of the embedded fiber length. However, the value of τ a extrapolated to zero embedded length, τ i, is comparable to the maximum ISS value, τmax, determined from the Raman analysis. The influence on the results of radial compression and geometric factors, such as droplet shape and size and separation of the knife edges, is also discussed.
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Her, Shiuh Chuan, e Bo Ren Yao. "Stress Analysis of Composite Material Embedded with Optical Fiber Sensor Subjected to In-Plane Shear". Advanced Materials Research 139-141 (outubro de 2010): 137–40. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.137.
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Optical fiber sensor with small size, light weight and immunity to electromagnetic interference can be embedded and integrated into the host material to form an ideally smart structure system. One must recognize that optical fibers are foreign entities to the host structure, therefore will induce high stress state in the vicinity of the embedded sensor irrespective of the small size of the fiber. To address this concern, present paper focuses the attention on constituent interaction between the optical fiber, coating, matrix and host material. An analytical model to predict the stress fields in the vicinity of the embedded optical fiber is presented. The theoretical development is based on the four concentric cylinders model which represents the optical fiber, protective coating, matrix and host material, respectively. The host material is considered to be a composite with reinforced fiber parallel to the optical fiber. In this investigation, the host structure is subjected to in-plane shear loading. The effects of the coating and host material on the stress distribution in the vicinity of the embedded optical fiber are presented through a parametric study.
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Ho, Ha Vinh, Eunsoo Choi e Jun Won Kang. "Analytical bond behavior of cold drawn SMA crimped fibers considering embedded length and fiber wave depth". REVIEWS ON ADVANCED MATERIALS SCIENCE 60, n.º 1 (1 de janeiro de 2021): 862–83. http://dx.doi.org/10.1515/rams-2021-0066.
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Abstract The NiTi SMA fibers were cold drawn to introduce prestrain, and then, they were made to crimped fibers with various wave depths. The recovery stress was measured, which was useful for closing the cracks in fiber-reinforced concrete. The pullout behaviors were also examined considering the existing recovery stress, and it is found that the recovery stress did not influence so much on the pullout behavior. According to the pullout results, a parametric study used a finite element analyzing (FEA) model to quantify the cohesive surface model’s parameters and the value of the friction coefficient. Then, the developed model is used to investigate the crimped fiber’s pullout behavior with various embedded lengths and wave depths. When the fiber in the elastic range, the peak stresses significantly raise due to increasing embedded waves; they show a linear relationship. After the yield of the SMA fiber, the peak stresses are also a function of embedded waves; however, the increasing trend is slow down. Concerning the cost, the even distribution of the fiber, and for guaranteeing the fiber experiences the pulling out, it is recommended that the embedded lengths and corresponding wave depths should be designed to avoid the yield.
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Chung, Ilsup, e Y. Jack Weitsman. "Model for the Micro-Buckling/Micro-Kinking Compressive Response of Fiber-Reinforced Composites". Applied Mechanics Reviews 47, n.º 6S (1 de junho de 1994): S256—S261. http://dx.doi.org/10.1115/1.3124419.
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This article focuses on the effects that non-uniform fiber spacings have on the compressive response of composites. The above type of imperfection is included in a model which incorporates initial fiber misalignments and accounts for non-linear shear response of the matrix and shear-deformable fibers. It is shown that the disparate response of fibers embedded within matrix layers of different thicknesses results in reduced levels of compressive strengths and leads to failure modes which contain discontinuities in the fiber shear strains.
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Liang, Xiaodong, Kai Li e Shengqiang Cai. "Drying-Induced Deformation in Fiber-Embedded Gels to Mimic Plant Nastic Movements". International Journal of Applied Mechanics 07, n.º 02 (abril de 2015): 1550016. http://dx.doi.org/10.1142/s1758825115500167.
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Pinecone scales and seedpod valves can deform in response to environmental humidity change, which is categorized as nastic movements. In this article, inspired by their tissue structure, we use fiber-embedded gels to model the nastic movements of pinecone scales and seedpod valves. In the model, stiffer and less swellable fibers orient inhomogeneously in the gel matrix. Depending on the arrangement of fibers, the gel matrix may bend or twist when it shrinks, caused by the decrease of environmental humidity. Our simulations demonstrate the possibilities of achieving different deformation modes in fiber-embedded gels through initially specified fiber arrangements. The numerical modeling methods presented in the article may find their applications in biomimetic designs with responsive gels.
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Gao, Jian Hong, e Xiao Xiang Yang. "Evaluation of 3D Embedded Element Technique in the Finite Element Analysis for the Composite". Key Engineering Materials 801 (maio de 2019): 65–70. http://dx.doi.org/10.4028/www.scientific.net/kem.801.65.
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RVE combined with finite element analysis (FEA) is a very popular method to predict the mechanical property of the composite reinforced by short fibers. In the conventional method, generally the “tie” approach is used. By this method, the FE model with high fiber aspect ratio can not be achieved and the non-convergence of the numerical calculation may appear because of the complex mesh. The embedded element techinique is considered to be a replaceable method . Using this method, the mechanical behavior of composite with high fiber aspect ratio would be simulated. Therefore, in this study, the 3D solid element was employed for the FE model with multi cylinder particles. The comparisions of the Mise stress and the displacement between the embedded and conventional method indicate that compared with the stress transfer, the simulated result of composite stiffness is more accurate. In addition, the effects of model size, fiber orientated angle, fiber volume fraction and fiber aspect ratio were investigated. The numerical results were compared with the Mori-Tanaka model and the good agreements verify the applicability of the embedded element technique we studied in this paper.
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Wren, T. A. L., e D. R. Carter. "A Microstructural Model for the Tensile Constitutive and Failure Behavior of Soft Skeletal Connective Tissues". Journal of Biomechanical Engineering 120, n.º 1 (1 de fevereiro de 1998): 55–61. http://dx.doi.org/10.1115/1.2834307.
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We propose a microstructural model for the uniaxial tensile constitutive and failure behavior of soft skeletal connective tissues. The model characterizes the tissues as two-phase composites consisting of collagen fibers embedded in ground substance. Nonlinear toe region behavior in the stress versus strain curve results from the straightening of crimped fibers and from fiber reorientation. Subsequent linear behavior results from fiber stretching affected by fiber volume fraction, collagen type, crosslink density, and fiber orientation. Finally, the tissue fails when fibers successively rupture at their ultimate tensile strain. We apply the model to tendon, meniscus, and articular cartilage. The model provides a consistent approach to modeling the tensile behavior of a wide range of soft skeletal connective tissues.
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Gao, Jian Hong, Xiao Xiang Yang e Li Hong Huang. "Application of Embedded Element in the Short Fiber Reinforced Composite". Key Engineering Materials 774 (agosto de 2018): 241–46. http://dx.doi.org/10.4028/www.scientific.net/kem.774.241.
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The finite element analysis (FEA) is a numerical method for predicting the mechanical property of short fiber reinforced composite usefully. However, as we know, there is always a “jamming” limit when generating fiber architecture expecially in the cases of high volume fraction and high aspect ratio of short fiber. Even if the volume fraction and aspect ratio in finite element model meet the practical requirements, the problem of mesh deformity will always occur which would lead to unconverge of numerical computation. In this work, embedded element technique which will help to reduce the probability of the above two problems is employed to establish the finite element model of short fiber reinforced composite. The effect of edge size, thickness and mesh density of FE models on the elastic modulus were investigated. Numerical results show that the value of elastic modulus mainly depend on the edge size and fiber amount of FE model while the effect of thickness can be neglected. The elastic modulus takes to converge for high element number. An inverse method is proposed to calculate volume fraction of short fibers, by which numerical results agree well with the calculation results of empirical formula based on Halpin-Tsai equation.
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Huang, Yizhe, Zhifu Zhang, Chaopeng Li, Kuanmin Mao e Qibai Huang. "Modal Performance of Two-Fiber Orthogonal Gradient Composite Laminates Embedded with SMA". Materials 13, n.º 5 (2 de março de 2020): 1102. http://dx.doi.org/10.3390/ma13051102.
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A gradient composite laminate that was composed of two-phase fibers, a shape memory alloy (SMA), and graphite was prepared to investigate modal performance and improve vibration behavior. The stress-strain relation of the single-layer composite plates was derived from Kirchhoff thin plate theory and the material constitutive of the SMA. A gradient distribution model and the eigenvalue equations of gradient composite laminates were developed. The influence of the fiber component content gradient distribution, pre-strain, the two-phase fiber volume fraction, and geometric parameters on the modal performance was analyzed. This study provides a method to avoid the structural resonance of composite laminates that are embedded with an SMA through the gradient distribution of two-phase fiber content that leads to the interaction of the material properties.
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Zulkarnain, Muhammad, Zaimi Zainal Mukhtar e Ikhwan Yusof. "Effect of Steel Fiber Reinforced in FRP Confined Concrete by Using Numerical Analysis". Key Engineering Materials 879 (março de 2021): 202–12. http://dx.doi.org/10.4028/www.scientific.net/kem.879.202.
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The models are predicting and analyzing on compressive and flexural testing by considering fiber reinforcement embedded in confinement concrete. In this work, steel 4340 fiber with high aspect ratio was developed in unique random spline shape and randomly disperse in confinement concrete. Fibers designed in 15.5mm of average length and amount were varied in range of 50 to 200 and 250 to 1000 for compressive and flexural testing, respectively. Both varied orientation and random dispersion of fiber were developed using MATLAB before embedded and analyzed in Ansys Workbench. The finite element model was validated in initial results on plain concrete prior study in influence of confining and fibers to structure. The model proposed showed that confining reinforcement increasing ductility and large deflections in structure testing. In addition, fibers as reinforcement slightly increases in strength for both compressive and flexural in certain number. These method reinforcement was help warning of failure prior to complete failure that use in construction material.
Teses / dissertações sobre o assunto "Embedded fiber model"
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Rukavina, Tea. "Multi-scale damage model of fiber-reinforced concrete with parameter identification". Thesis, Compiègne, 2018. http://www.theses.fr/2018COMP2460/document.
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Dans cette thèse, plusieurs approches de modélisation de composites renforcés par des fibres sont proposées. Le matériau étudié est le béton fibré, et dans ce modèle, on tient compte de l’influence de trois constituants : le béton, les fibres, et la liaison entre eux. Le comportement du béton est analysé avec un modèle d’endommagement, les fibres d'acier sont considérées comme élastiques linéaires, et le comportement sur l'interface est décrit avec une loi de glissement avec l’extraction complète de la fibre. Une approche multi-échelle pour coupler tous les constituants est proposée, dans laquelle le calcul à l'échelle macro est effectué en utilisant la procédure de solution operator-split. Cette approche partitionnée divise le calcul en deux phases, globale et locale, dans lesquelles différents mécanismes de rupture sont traités séparément, ce qui est conforme au comportement du composite observé expérimentalement. L'identification des paramètres est effectuée en minimisant l'erreur entre les valeurs calculées et mesurées. Les modèles proposés sont validés par des exemples numériquesIn this thesis, several approaches for modeling fiber-reinforced composites are proposed. The material under consideration is fiber-reinforced concrete, which is composed of a few constituents: concrete, short steel fibers, and the interface between them. The behavior of concrete is described by a damage model with localized failure, fibers are taken to be linear elastic, and the behavior of the interface is modeled with a bond-slip pull-out law. A multi-scale approach for coupling all the constituents is proposed, where the macro-scale computation is carried out using the operator-split solution procedure. This partitioned approach divides the computation in two phases, global and local, where different failure mechanisms are treated separately, which is in accordance with the experimentally observed composite behavior. An inverse model for fiber-reinforced concrete is presented, where the stochastic caracterization of the fibers is known from their distribution inside the domain. Parameter identification is performed by minimizing the error between the computed and measured values. The proposed models are validated through numerical examples
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Vassalié, Anthony. "Description et modélisation de l’endommagement d’un composite à matrice céramique sous sollicitations thermomécaniques". Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0259.
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Les composites à matrice céramique (CMC) présentent un fort intérêt dans le domaine aéronautique grâce à leurs excellentes propriétés thermomécaniques. Ils sont donc envisagés pour remplacer les alliages métalliques dans les parties chaudes des moteurs d'avions civils, afin de concevoir des pièces plus légères, ou permettant d'obtenir de meilleurs rendements. Ces matériaux présentent néanmoins un comportement complexe, notamment à cause de leur structure multi-échelle, architecturée et hétérogène. Dans ce contexte, ces travaux s’intéressent à l’amélioration de la compréhension du comportement mécanique en traction de CMC avec des fibres et une matrice en carbure de silicium, complétée d'une étape de Melt Infiltration (dits SiC/SiC MI). L'objectif est de mieux comprendre l'effet des propriétés des constituants microscopiques sur le comportement macroscopique jusqu'à rupture, via deux axes distincts mais complémentaires : la caractérisation mécanique de l'endommagement de ces CMC et leur modélisation par une méthode éléments finis. Dans une première partie, des essais de traction multi-instrumentés sont proposés (émissions acoustiques, corrélation d'images numériques, microscopie, etc.), afin d'obtenir une meilleure description des mécanismes à l'échelle du constituant et de leurs effets sur les échelles supérieures. Des caractérisations post-mortem supplémentaires sont également proposées, dans le but d'acquérir des informations sur les propriétés intrinsèques des phases directement à l'échelle microscopique, qui présentent un intérêt majeur pour la mise en place d'un modèle numérique. Ces différentes observations permettent de dresser un scénario d'endommagement jusqu'à rupture pour les matériaux SiC/SiC MI. Dans une seconde partie, une approche de modélisation éléments finis originale, par fibres intégrées, est proposée pour simuler le comportement jusqu'à rupture de ces derniers. En s'appuyant sur les observations expérimentales, les mécanismes d'intérêt sont sélectionnés et représentés dans le modèle, qui intégre le comportement des phases microscopiques directement aux échelles supérieures. Le modèle permet ainsi d'obtenir les mécanismes d'endommagement principaux à ces échelles, validés par les comparaisons essai/calcul, en ne s'appuyant que sur les propriétés des phases microscopiques. Les simulations permettent de mettre en évidence le rôle des différents constituants sur le comportement jusqu'à rupture des SiC/SiC MI, et ouvrent là voie à des travaux futurs sur cette famille de CMCCeramic matrix composites (CMCs) are materials of interest in the field of aeronautic because of their exceptional mechanical properties at elevated temperatures, making them promising candidates to replace metal alloys in high-temperature components of aircraft engines. Nevertheless, these materials also exhibit a complex behavior, especially because they are multi-scale, architectured and heterogeneous. In this context, this work tends to improve the understanding of the mechanical behavior under tension of CMCs composed of fibers and matrix made of silicon carbide, with a Melt Infiltration process (named SiC/SiC MI). To better understand the effects of microscopic phases on the macroscopic behavior until the final failure of the material, two distinct but complementary axis are explored : the mechanical characterizing of the damage of these CMCs and their modelling with a finite element method. Firstly, multi-instrumented tensile tests are carried out (acoustic emissions, digital image correlation, microscope, etc.), to obtain a better description of the phenomenon at micro-scale and their effects on upper scales. Post-mortem characterization are also performed in order to quantify the properties of the microscopic phases, which are of great interest to develop the numerical model. Thus, a damage scenario until the final failure is proposed for SiC/SiC MI materials. In a second part, a genuine finite element model approach, with embedded fiber, is proposed to simulate the mechanical behavior of these materials. Based on experimental observations, mechanisms of interest at micro-scale are selected and implemented in the model directly at upper scales. The developed approach demonstrates the ability to capture both the main damage phenomenon at micro-scale and the meso-scale behavior of CMCs, in good agreement with experimental results, offering a valuable tool for understanding and predicting their mechanical behavior until the final failure, and paving the way for further developments
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Kiesling, Thomas C. "Impact failure modes of graphite epoxy composites with embedded superelastic nitinol". Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-09162005-115046/.
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Piccioni, Flavio. "Numerical Evaluation of Mode II Disbonding on Fiberglass CCPs-Specimens and Material Characterization Utilizing a Distributed Sensing Rayleigh Backscattering System". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/19848/.
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Nowadays, composite materials have become the main construction materials for aeronautical structures, replacing traditional materials commonly used in this industry. However, composite structures are still characterized by conservative designs due to the lack of understanding from a physics-based approach their damage propagation and failure mechanisms. Since repairs of composite structures are a crucial part of the long-term use of composites in aerospace, the stakeholders require an in depth understanding of the physics of disbonding in composites. The aim of this research is a numerical evaluation of mode II disbonding on Center Cut Plies (CCPs) specimens with a preliminary study on material characterization performed through a Distributed Sensing System (DSS). In order to fulfill the objectives of this research, CCPs specimens manufactured from unidirectional fiber prepregs will be considered. The specimens will be produced from unidirectional prepregs in order to minimize the effects of residual stress fields introduced into the specimen during the curing process. That residual stress field will be evaluated and monitored making use of a Distributed Sensing System (DSS) optical fiber mounted and embedded within the laminas of the specimen. In addition, an analytical and numerical approach through FEM analysis will be adopted and validated to verify the experimental results obtained from the DSS.
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Kergosien, Nina. "Etude de l'intégration de transducteurs piézoélectriques à coeur de matériaux composite de type aéronautique pour le contrôle santé intégré par ondes de Lamb". Electronic Thesis or Diss., Ecully, Ecole centrale de Lyon, 2024. http://www.theses.fr/2024ECDL0008.
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Des systèmes CSI sont actuellement à l'étude pour vérifier l'intégrité des matériaux composites des aéronefs. Ils permettent d’optimiser la maintenance, en donnant la possibilité de suivre l’état des structures en temps réel ou de contrôler ponctuellement des pièces difficiles d’accès par les méthodes de CND courantes. Les matériaux composites offrent la possibilité d’intégrer un système CSI directement à cœur du matériau. De cette façon, l’instrumentation est protégée de l’environnement et les problématiques de collage en surface sont résolues. L'objectif de cette thèse est de déterminer les effets de l'intégration de transducteurs ultrasonores piézoélectriques à cœur d'un composite PRFC stratifié de type aéronautique sur leur comportement en émission et en réception afin de montrer les avantages et inconvénients d'une telle intégration à cœur pour le monitoring de ces structures par ondes de Lamb. Les transducteurs PZT minces se sont révélés être les transducteurs les plus adaptés à l'intégration, car ils supportent les conditions d'élaboration d'un composite de structures aéronautiques élaboré en autoclave (7 bar et 180°C) et sont capables d'émettre et de recevoir des ondes guidées se propageant dans les plaques. La méthode d'intégration a été adaptée pour préserver l'intégrité des PZT et optimiser leur capacité d'émission d'ondes dans un composite. A cette occasion, la capacité des mesures d'impédance électromécanique à vérifier rapidement l'efficacité de la mise en œuvre de l'intégration a été validée. La caractérisation du champ d'onde qA0 a été réalisée expérimentalement, grâce aux déplacements hors plan mesurées avec un vibromètre laser suite à l'excitation de disques PZT intégrés à des fréquences comprises entre 30 et 200 kHzLa capacité du PZT intégré à détecter un défaut simulé de type aimant est aussi étudiée en essai d'émission-réception et est comparé avec le comportement de PZT couplés en surface de composite. Une étude par modélisation fréquentielle multiphysique a ensuite été réalisée afin de mettre en évidence les phénomènes physiques mis en jeu par l'intégration d'un PZT à cœur de composite. Ainsi, la direction des plis en contact du PZT intégré, la profondeur d'intégration et le couplage du PZT au composite influent sur le mécanisme de transduction ultrasonore. De plus, les contraintes induites par l'actionneur PZT ne permettent pas d'être simplifiées sous forme d'un modèle de type pin-force habituellement utilisé comme chargement d'un PZT en surface de matériau isotrope. En effet, les contraintes induites localement par l'excitation du PZT intégré ne sont pas radiales et dépendent de l'électrode du PZT considérée ainsi que des fréquences de génération d'ondesSHM systems are currently being developed to check the integrity of aircraft composite materials. These systems will help optimize maintenance by enabling real-time monitoring of structural condition, or spot-checking of parts that are difficult to access using conventional NDT methods. Composite materials offer the possibility of integrating a SHM system directly into the material. In this way, the instrumentation is protected from the environment and surface bonding issues are resolved. The aim of this thesis is to determine the effects of integrating piezoelectric transducers into the core of an aeronautical laminated CFRP composite on their Lamb-wave emission and reception abilities, in order to demonstrate the advantages and disadvantages for the design of a defect detection SHM system. Thin PZT transducers proved to be the most suitable ones for integration, as they can withstand the processing conditions of an autoclave-processed composite (7 bar and 180°C). They are also capable of transmitting and receiving guided waves, which are propagating in the plates. Moreover, the integration method was adapted to preserve the integrity of the PZTs and to optimize their ability to transmit waves in a composite. In order to assess the effectiveness of the integration, electromechanical impedance measurements were made a fast checking process. Characterization of qA0 mode wavefield transmitted by embedded PZT was carried out experimentally. Surface-bonded and embedded PZT were excited at frequencies between 30 and 200 kHz, while out-of-plane displacements were measured with a laser vibrometer. The ability of the embedded PZT to detect a simulated magnet-type defect are also studied in pitch-catch tests, and compared with the behavior of surface-bonded PZT to the composite surface. A dynamic finite element modelling study was then conducted to highlight the physical phenomena induced by the integration of a PZT in the composite core. The direction of the plies in contact with the embedded PZT, the depth of integration and the coupling of the PZT with the composite are influencing the ultrasonic transduction mechanism. Furthermore, it appears that the stresses induced by the PZT actuator cannot be simplified by the pin-force model usually used to load a PZT on an isotropic material surface in flaw detection models. These stresses are not radially oriented and depend on the PZT electrode considered, as well as on the wave generation frequencies
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Kim, Jeongjoo. "A Time-Variant Probabilistic Model for Predicting the Longer-Term Performance of GFRP Reinforcing Bars Embedded in Concrete". Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-05-7943.
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Although Glass Fiber Reinforced Polymer (GFRP) has many potential advantages as reinforcement in concrete structures, the loss in tensile strength of the GFRP reinforcing bar can be significant when exposed to the high alkali environments. Much effort was made to estimate the durability performance of GFRP in concrete; however, it is widely believed the data from accelerated aging tests is not appropriate to predict the longer-term performance of GFRP reinforcing bars. The lack of validated long-term data is the major obstacle for broad application of GFRP reinforcement in civil engineering practices. The main purpose of this study is to evaluate the longer-term deterioration rate of GFRP bars embedded in concrete, and to develop an accurate model that can provide better information to predict the longer-term performance of GFRP bars. In previous studies performed by Trejo, three GFRP bar types (V1, V2, and P type) with two different diameters (16 and 19 mm [0.625, and 0.7 in. referred as #5 and #6, respectively]) provided by different manufacturers were embedded in concrete beams. After pre-cracking by bending tests, specimens were stored outdoors at the Riverside Campus of Texas A&M University in College Station, Texas. After 7 years of outdoor exposure, the GFRP bars were extracted from the concrete beams and tension tests were performed to estimate the residual tensile strength. Several physical tests were also performed to assess the potential changes in the material. It was found that the tensile capacity of the GFRP bars embedded in concrete decreased; however, no significant changes in modulus of elasticity (MOE) were observed. Using this data and limited data from the literature, a probabilistic capacity model was developed using Bayesian updating. The developed probabilistic capacity model appropriately accounts for statistical uncertainties, considering the influence of the missing variables and remaining error due to the inexact model form. In this study, the reduction in tensile strength of GFRP reinforcement embedded in concrete is a function of the diffusion rate of the resin matrix, bar diameter, and time. The probabilistic model predicts that smaller GFRP bars exhibit faster degradation in the tensile capacity than the larger GFRP bars. For the GFRP bars, the model indicates that the probability that the environmental reduction factor required by The American Concrete Institute (ACI) and the American Association of State Highway Transportation Officials (AASHTO) for the design of concrete structures containing GFRP reinforcement is below the required value is 0.4, 0.25, and 0.2 after 100 years for #3, #5, and #6, respectively. The ACI 440 and AASHTO design strength for smaller bars is likely not safe.
Livros sobre o assunto "Embedded fiber model"
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Cheng, Russell. Embedded Distributions: Two Numerical Examples. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198505044.003.0007.
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This chapter illustrates use of (i) the score statistic and (ii) a goodness-of-fit statistic to test if an embedded model provides an adequate fit, in the latter case with critical values calculated by bootstrapping. Also illustrated is (iii) calculation of parameter confidence intervals and CDF confidence bands using both asymptotic theory and bootstrapping, and (iv) use of profile log-likelihood plots to display the form of the maximized log-likelihood and scatterplots for checking convergence to normality of estimated parameter distributions. Two different data sets are analysed. In the first, the generalized extreme value (GEVMin) distribution and its embedded model the simple extreme value (EVMin) are fitted to Kevlar-fibre breaking strength data. In the second sample, the four-parameter Burr XII distribution, its three-parameter embedded models, the GEVMin, Type II generalized logistic and Pareto and two-parameter embedded models, the EVMin and shifted exponential, are fitted to carbon-fibre strength data and compared.
Capítulos de livros sobre o assunto "Embedded fiber model"
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Wei, Liang, John D. Marshall e J. Renée Brooks. "Process-Based Ecophysiological Models of Tree-Ring Stable Isotopes". In Stable Isotopes in Tree Rings, 737–56. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92698-4_26.
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AbstractTree-ring stable isotopes can be used to parameterizeprocess-based models by providing long-term data on tree physiological processes on annual or finer time steps. They can also be used to test process-based ecophysiological models for the assumptions, hypotheses, and simplifications embedded within them. However, numerous physiological and biophysical processes influence the stable carbon (δ13C) and oxygen (δ18O) isotopes in tree rings, so the models must simplify how they represent some of these processes to be useful. Which simplifications are appropriate depends on the application to which the model is applied. Fortunately, water and carbon fluxes represented in process-based models often have strong isotopic effects that are recorded in tree-ring signals. In this chapter, we review the status of several tree-ring δ13C and δ18O models simulating processes for trees, stands, catchments, and ecosystems. This review is intended to highlight the structural differences among models with varied objectives and to provide examples of the valuable insights that can come from combining process modeling with tree-ring stable isotope data. We urge that simple stable isotope algorithms be added to any forest model with a process representation of photosynthesis and transpiration as a strict test of model structure and an effective means to constrain the models.
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Gehrke, Mai, Tomáš Jakl e Luca Reggio. "A Duality Theoretic View on Limits of Finite Structures". In Lecture Notes in Computer Science, 299–318. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-45231-5_16.
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AbstractA systematic theory of structural limits for finite models has been developed by Nešetřil and Ossona de Mendez. It is based on the insight that the collection of finite structures can be embedded, via a map they call the Stone pairing, in a space of measures, where the desired limits can be computed. We show that a closely related but finer grained space of measures arises — via Stone-Priestley duality and the notion of types from model theory — by enriching the expressive power of first-order logic with certain “probabilistic operators”. We provide a sound and complete calculus for this extended logic and expose the functorial nature of this construction.The consequences are two-fold. On the one hand, we identify the logical gist of the theory of structural limits. On the other hand, our construction shows that the duality-theoretic variant of the Stone pairing captures the adding of a layer of quantifiers, thus making a strong link to recent work on semiring quantifiers in logic on words. In the process, we identify the model theoretic notion of types as the unifying concept behind this link. These results contribute to bridging the strands of logic in computer science which focus on semantics and on more algorithmic and complexity related areas, respectively.
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Tran, Quoc Khanh, e Ngoc Thanh Tran. "Investigation and Prediction of Pullout Behavior of Twisted Fibers from Ultra High Strength Concrete". In Advances in Transdisciplinary Engineering. IOS Press, 2024. https://doi.org/10.3233/atde241013.
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This research demonstrates the pullout response of twisted steel fibers from various matrices. The high strength twisted steel fibers, characterized by three twists along their length and a high aspect ratio of 100, were embedded in two types of matrix: high strength concrete (HSC) matrix with a compressive strength of 81 MPa and ultra high strength concrete (UHSC) matrix with a compressive strength of 152 MPa. Moreover, a theoretical model was established to estimate the pullout response of twisted fibers. The experiment results revealed that twisted fibers embedded in the HSC matrix exhibited slip-hardening behavior by maintaining pullout mode during the fiber pullout from matrix, whereas those in the UHSC matrix exhibited brittle failure due to fiber rupture. The HSC matrix produced a 41% lower maximum pullout load but a 1217% higher pullout energy than the UHSC matrix. The theoretical model was able to accurately capture the pullout behavior of twisted fibers from different matrices.
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Lamberti, A., G. Chiesura, B. DePauw e S. Van landuit. "Combining embedded Fibre Bragg Grating sensors and modal analysis techniques to monitor fatigue induced propagating delaminations in composite laminates". In Emerging Technologies in Non-Destructive Testing VI, 537–42. CRC Press, 2015. http://dx.doi.org/10.1201/b19381-88.
Texto completo da fonteTrabalhos de conferências sobre o assunto "Embedded fiber model"
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Rickert, Lucas, Daniel Vajner, Martin v. Helversen, Johannes Schall, Sven Rodt, Stephan Reitzenstein, Kinga Zolnac et al. "Fiber-pigtailed Quantum Dot Hybrid Circular Bragg Gratings". In Quantum 2.0, QM5B.3. Washington, D.C.: Optica Publishing Group, 2024. http://dx.doi.org/10.1364/quantum.2024.qm5b.3.
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We report on the deterministic fabrication of high-performance hybrid circular Bragg gratings (hCBGs) with embedded InAs/GaAs quantum dots and their direct and permanent fiber-pigtailing to single mode fibers. The devices exhibit spontaneous emission lifetimes <50ps resulting in experimental Purcell factor well beyond 15. The fiber-pigtailed devices show excellent temperature stability and unprecedented performance in terms of the single photon purity.
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Wang, Xiaochun. "A New Embedded-Zone Method on Computation of the Transverse Elastic Properties of Fiber-Reinforced Composites". In ASME 2005 Pressure Vessels and Piping Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/pvp2005-71713.
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There are many methods on computation of transverse elastic properties of unidirectional fiber-reinforced composites when using the finite element method, such as three-dimension model, two-dimension plane strain model, unit cell model, etc[1]. But unit cell models could be used only when the fibers are arrayed regularly. The computations of three- and two-dimension plane strain models are tremendous when many fine fibers are spread randomly in the matrix so that the properties of block of composite must be computed. The paper proposes a new embedded-zone method to compute the transverse elastic properties for a block of fiber-reinforced composites containing a great amount of fibers embedded in the matrix stochastically while using very little computational work compared with three- and two-dimension plane strain model. The transverse elastic modulus and shear modulus of unidirectional fiber-reinforced composites are computed.
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Dong, Yongtao, Qingbin Li e Farhad Ansari. "Shear Lag Model for Embedded Interferometric Optical Fiber Sensors". In Engineering Mechanics Conference 2000. Reston, VA: American Society of Civil Engineers, 2000. http://dx.doi.org/10.1061/40495(302)5.
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Sirkis, James S. "Phase-strain-temperature model for structurally embedded interferometric optical fiber strain sensors with applications". In OE Fiber - DL tentative, editado por Richard O. Claus e Eric Udd. SPIE, 1991. http://dx.doi.org/10.1117/12.50162.
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Krueper, Gregory, Lior Cohen, Robert Mellors, Stephen B. Libby, Michael Messerly, Joshua Combes e Juliet T. Gopinath. "Quantum Multiparameter Estimation Model of Cascaded Phases in Optical Fiber". In CLEO: Applications and Technology. Washington, D.C.: Optica Publishing Group, 2023. http://dx.doi.org/10.1364/cleo_at.2023.jth2a.17.
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We present a new architecture for quantum-enhanced multiparameter estimation, where measured phases are cascaded along a single optical fiber. Embedded reflectors separate these phases, enabling novel fiber-based quantum distributed sensing of temperature and strain.
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Sirkis, James S., e Henry W. Haslach, Jr. "Complete phase-strain model for structurally embedded interferometric optical fiber sensors". In San Jose - DL tentative, editado por Richard O. Claus e Eric Udd. SPIE, 1990. http://dx.doi.org/10.1117/12.24846.
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Aimmanee, Sontipee, Supharoek Trakarnkulchai e Pakinee Aimmanee. "Micromechanics of a Smart Composite Actuator Embedded With Hollow Piezoelectric Fibers". In ASME 2011 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2011. http://dx.doi.org/10.1115/smasis2011-5126.
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This paper presents a development of mathematical models for predicting the effective elastic and piezoelectric properties of a Smart Composite Actuator (SCA) reinforced with transversely isotropic piezoelectric hollow fibers. The models are established based on micromechanics of representative volume element of concentric cylinders or so-called concentric cylinder model (CCM). Five elastic constants and two piezoelectric coefficients are predicted as a function of fiber volume fraction, matrix volume fraction, and their constituents’ properties in the SCA. Numerical results of a chosen material system are obtained and discussed. The models can be found useful for developing a SCA or a novel hollow fiber-reinforced composite with the desired properties.
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Ghonem, Hamouda. "A Model for Fracture of Bridging Fibers in Titanium Metal Matrix Composites". In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0507.
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Abstract This paper investigates the fatigue failure of SiC fibers bridging a fatigue crack in unidirectional reinforced titanium matrix composites. For this purpose, an experimental/computational fiber fracture model is developed on the basis of the occurrence of two damage events taking place along a bridging fiber. These events are the time-dependent evolution of axial stresses and the simultaneous strength degradation of the fiber due to cyclic-related damage processes. The stress evolution in a fiber is calculated using the finite element method employing a cylinder model of a fiber embedded in a cracked matrix phase. The model considers the visco-plastic behavior of the matrix phase at elevated temperature loadings. The failure strength of the as-received SiC fiber are determined through a series of monotonic tension, residual fatigue strength and fatigue-life tests performed on SiC fibers at different temperatures. In order to take into account the notch-like effects resulting from the presence of fiber coating cracks and possible deflection of fiber/matrix interfacial cracks, the fatigue strength of the as-received SiC fiber was modified using an elastic stress localization. The resulting fatigue strength of bridging fibers was found to be about 56% less than the corresponding strength of as-received fibers. The fiber stress evolution curve and the modified fatigue strength curve were then combined to predict the life of bridging fibers. Results of the model are compared with those obtained experimentally for bridging fibers in SiC/Timetal-21S composite subjected to load conditions including low and high loading frequency at room temperature, 500 and 650 °C.
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Ghasemi Nejhad, Mehrdad N., e Davood Askari. "Micromechanics of Longitudinal Mechanical Properties for Active Fiber Composites With Embedded Metal-Core Piezoelectric Fibers". In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-82721.
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An analytical micromechanics approach is presented to model the effective longitudinal mechanical properties of Metal-Core Piezoelectric Fibers (MPF). The model assumes general orthotropic material properties for the piezoelectric as well as the core material. Next, the general orthotropic solution is reduced to transversely isotropic for the piezoelectric fiber and isotropic for the metal-core. This MPF system is also modeled using finite element analysis (FEA) and the results from the analytical solution and FEA are compared for verification purpose. Next, the Metal-Core Piezoelectric Fiber (MPF) is embedded inside a metal or a polymer and the resulting longitudinal mechanical properties of these Active Fiber Composite (AFC) systems are given analytically.
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Parnas, Richard S., e Dara L. Woerdeman. "Mode Coupling Theory for Evanescent Wave Optical Fiber Sensors". In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0628.
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Abstract Optical fiber based sensors have potential in the composites processing industry as well as many other industries, but cost and robustness often mitigate the advantages of optical fiber sensors. The least expensive type of optical fiber sensor is a length of fiber either embedded in the part or in distal contact with the part surface. In the case of embedded evanescent mode sensors, important issues hinge on interpreting the evanescent signal obtained during processing or in service inspection. An optical model based on mode coupling theory is presented below to provide a description of the sensing volume around the fiber from which signal is collected during evanescent measurements. The model is developed for a fluorescence sensor but the optical theory could be equally applied for infrared or other types of optical fiber sensors.
Relatórios de organizações sobre o assunto "Embedded fiber model"
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Slaughter, William S., J. L. Sanders e Jr. A Model for Load-Transfer from an Embedded Fiber to an Elastic Matrix. Fort Belvoir, VA: Defense Technical Information Center, agosto de 1990. http://dx.doi.org/10.21236/ada228466.
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STUDY ON MECHANICAL PROPERTIES OF STAINLESS STEEL PLATE SHEAR WALL STRENGTHENED BY CORRUGATED FRP. The Hong Kong Institute of Steel Construction, agosto de 2022. http://dx.doi.org/10.18057/icass2020.p.305.
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In this paper, the mechanical properties of stainless steel plate shear walls reinforced with fiber reinforced polymer (FRP) of corrugated sections were studied. Two scaled FRP-stainless steel plate shear wall specimens were designed and subjected to the monotonic horizontal load. FRPs in the form of corrugated and flat sections were respectively used to reinforce the embedded steel plates of the steel plate shear wall. The test results show that the failure mode of flat FRP reinforced steel plate shear wall is mainly the peeling of the FRP, while the failure mode of corrugated FRP reinforced steel plate shear wall is mainly the tensile fracture of the FRP. The out-of-plane deformation of steel plate reinforced with corrugated FRP can be effectively restrained. The maximum bearing capacity of the two specimens is 97.96 kN and 106.32 kN respectively. The yield load of the specimen with corrugated FRP is increased by 16.5%, the ultimate bearing capacity is increased by 9.3% and the stiffness is increased by 68%.