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Artykuły w czasopismach na temat "Essai Double Cantilever Beam (DCB)"
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Alfred Franklin, V., T. Christopher i B. Nageswara Rao. "Influence of Root Rotation on Delamination Fracture Toughness of Composites". International Journal of Aerospace Engineering 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/829698.
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Large deviations have been observed while analysing composite double cantilever beam (DCB) specimens assuming each cracked half as a simple cantilever beam. This paper examines the effect of rotational spring stiffness(K)on the critical fracture energy(GIC)considering nonzero slope at the crack-tip of the DCB specimen by modelling each cracked half as the spring-hinged cantilever beam. The critical load estimates of DCB specimens fromGICare found to be in good agreement with in-house and existing test results of different composite material systems.
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Chen, T., C. M. Harvey, S. Wang i V. V. Silberschmidt. "Analytical corrections for double-cantilever beam tests". International Journal of Fracture 229, nr 2 (czerwiec 2021): 269–76. http://dx.doi.org/10.1007/s10704-021-00556-5.
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AbstractDouble-cantilever beams (DCBs) are widely used to study mode-I fracture behavior and to measure mode-I fracture toughness under quasi-static loads. Recently, the authors have developed analytical solutions for DCBs under dynamic loads with consideration of structural vibration and wave propagation. There are two methods of beam-theory-based data reduction to determine the energy release rate: (i) using an effective built-in boundary condition at the crack tip, and (ii) employing an elastic foundation to model the uncracked interface of the DCB. In this letter, analytical corrections for a crack-tip rotation of DCBs under quasi-static and dynamic loads are presented, afforded by combining both these data-reduction methods and the authors’ recent analytical solutions for each. Convenient and easy-to-use analytical corrections for DCB tests are obtained, which avoid the complexity and difficulty of the elastic foundation approach, and the need for multiple experimental measurements of DCB compliance and crack length. The corrections are, to the best of the authors’ knowledge, completely new. Verification cases based on numerical simulation are presented to demonstrate the utility of the corrections.
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Sponseller, David L., i Thomas E. Sponseller. "The Double Cantilever Beam (DCB) Test at Forty". BHM Berg- und Hüttenmännische Monatshefte 161, nr 1 (styczeń 2016): 19–26. http://dx.doi.org/10.1007/s00501-016-0449-7.
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Colonel, L., A. Calvez, F. Fournel, V. Larrey, S. Moreau, F. Mazen i F. Rieutord. "Double cantilever beam bonding energy measurement using confocal IR microscopy". Journal of Applied Physics 132, nr 21 (7.12.2022): 215106. http://dx.doi.org/10.1063/5.0114668.
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A new technique is assessed in order to measure, at the wafer scale, direct bonding energies. It is derived from the standard Double Cantilever Beam (DCB) method and uses interferometry in confocal IR laser source microscopy to measure crack openings. Such a bonding energy measurement protocol has better accuracy compared to other techniques. This is due to a better confocal microscopy resolution and the high intensity of the laser source. The elastic energy stored in bent wafers is obtained by measuring the beam curvature. DCB deformation models are discussed from the short-range crack opening theory to long distance beam-bending theories. Comparison is made between models, experimental results, and FEM simulations. Finally, the bonding energy error during standard measurements is estimated.
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Budzik, Michal K., i Henrik M. Jensen. "Evaluation of Defects in Adhesive Joint by Double Cantilever Beam Experiment". Key Engineering Materials 665 (wrzesień 2015): 101–4. http://dx.doi.org/10.4028/www.scientific.net/kem.665.101.
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We analyzed effects of interface/adhesive defects during fracture mechanical Mode I Double Cantilever Beam (DCB) tests of an adhesive joint. Two aluminium slabs were bonded using structural epoxy adhesive. A DCB experiment under static loading was conducted to estimate the critical fracture energy. During the ‘steady-state’ fracture we noted oscillating, random fluctuation in the force vs. displacement curve, and thus in the fracture energy. This is associated to the local variation of properties within the bondline and the interfaces. A simple model is derived to quantify the probable density of flaws observed experimentally.
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Wang, K. F., Y. Q. Wang, B. L. Wang i L. Zheng. "A double cantilever beam incorporating cohesive crack modeling for superconductors". Modern Physics Letters B 34, nr 15 (30.03.2020): 2050166. http://dx.doi.org/10.1142/s0217984920501663.
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In this paper, a double cantilever beam (DCB) specimen incorporating cohesive crack is developed for superconductors which have potential applications in high temperature superconducting cables in space solar power station. The cohesive interface is introduced along the crack front of the DCB model under electromagnetic force. The load-separation relation (i.e. the crack opening displacement) is used as the fracture mechanics parameter and the corresponding curves during fracture process are obtained and verified by the finite element numerical method. Results show that the presence of tensile electromagnetic force makes crack propagate easily. Superconductors with small cracks have good adaptability to the oscillation of magnetic fields while that with large cracks are easier to fracture during the descent of the magnetic field. In addition, the ductility ratio of the cohesive interface can significantly increase the fracture strength. The length of fracture zone decreases as the crack length increases.
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Dahlan, Hendery, Meifal Rusli, Mulyadi Bur i Rika Ampuh Hadiguna. "Kaji Teoritis Pengaruh Variasi Letak Retak Terhadap Perambatan Retak Dengan Pendekatan Double Cantilever Beam (DCB)". Jurnal Inovasi Rekayasa Mekanikal dan Termal 1, nr 2 (29.12.2023): 20–26. http://dx.doi.org/10.25077/inomet.1.2.20-26.2023.
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One of the causes of structural failure is the presence of defects in the form of cracks that appear during the manufacturing or usage process of the structure. The propagation of cracks in the structure greatly depends on the value of the energy released rate possessed by the defective structure. Therefore, it is necessary to calculate the energy released rate of a structure that has a crack. One simple approach is the double cantilever beam (DCB) method. The DCB approach is derived from the change in strain energy with respect to the change in crack length. In this study, variations in crack length and crack location will be analyzed using the DCB approach and compared with the Finite Element Method (FEM) approach. It can be concluded that the calculation of strain energy can be performed using the cantilever beam approach, where the results do not significantly differ from the FEM calculations. Additionally, the strain energy is heavily influenced by the length of the beam, as longer beams result in a significant increase in strain energy (cubic relationship). The value of Energy Released Rate (ERR) is highly influenced by the crack length; a longer initial crack length leads to a quadratic increase in the Energy Released Rate (ERR). Furthermore, the value of Energy Released Rate (ERR) is also affected by the crack location; the closer the crack is to the surface of the beam, the higher the Energy Released Rate (ERR) will be.
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Gourlie, A. D., G. N. Podolski i J. R. Fleet. "A Detailed Statistical Examination of the Double Cantilever Beam (DCB) Test". CORROSION 47, nr 9 (wrzesień 1991): 728–35. http://dx.doi.org/10.5006/1.3585859.
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Li, Rongzhi, Lin Ye i Yiu-Wing Mai. "Interlaminar Fracture of Stitched GFRP Laminates". Advanced Composites Letters 5, nr 1 (styczeń 1996): 096369359600500. http://dx.doi.org/10.1177/096369359600500101.
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The mode I interlaminar fracture of Kevlar thread stitched GFRP laminates has been studied using double-cantilever-beam (DCB) tests. It was found that stitching density and patterns influence interlaminar fracture performance of composites mainly through the different failure mechanisms of stitch threads during crack propagation.
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Balendran, B. "On the Double Cantilever Beam Specimen for Mode-I Interface Delamination". Journal of Applied Mechanics 61, nr 2 (1.06.1994): 471–73. http://dx.doi.org/10.1115/1.2901470.
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A compliance model is presented for a DCB specimen for mode-I interface delamination. The undelaminated part of the specimen is modeled by using Reissner’s mixed variational principle from which the rotation of the cross-section at the tip of the crack and the shear stress at the interface are evaluated. The results for a homogeneous beam with midplane crack are deduced and shown to be in better agreement with the experimental and finite element results than any of the existing models.
Rozprawy doktorskie na temat "Essai Double Cantilever Beam (DCB)"
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Peignon, Axel. "Contribution au développement de méthodes de caractérisation et de modélisation de LVL de peuplier en vue de leur usage dans la mobilité". Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSEI017.
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Cette thèse s’inscrit dans le projet « BOOST » (acronyme de « le BOis pOur les STructures des véhicules ») financé par l’Agence Nationale de la Recherche (ANR). Il s’agit d’un Projet de Recherche Collaboratif entre l’ICA (Institut Clément Ader) à Toulouse et le LaBoMaP (LaBoratoire des Matériaux et Procédés) à Cluny.Le bois est une ressource locale, à très faible empreinte carbone et renouvelable. Largement utilisé dans l’aéronautique, mais aussi dans l’automobile en tant que structure travaillante dans le passé, son réemploi devient aujourd’hui un enjeu de la bioéconomie (Mair-Bauernfeind et al., 2020; Skullestad et al., 2016). Dans ce domaine, des travaux récents montrent que le bois est un matériau « crédible » pour la substitution de matériaux métalliques dans les structures de véhicules (Baumann et al., 2020).Les résultats antérieurs de l’Institut Clément Ader démontrent les très bonnes qualités mécaniques du bois, et notamment du contreplaqué associé à des peaux métalliques ou composites en statique, impact et crash (Guélou, 2021; Susainathan, 2017). Le LaBoMaP a pour sa part développé une méthode d’identification optique de l’orientation des fibres de chaque pli déroulé composant le contreplaqué (Duriot, 2021; Viguier et al., 2018). L’objectif scientifique de cette thèse est donc de :- Caractériser des LVL de peuplier, tout en caractérisant l’effet de la pente de fil, l’influence du nombre de plis et d’autres caractéristiques propres au LVL ;- Caractériser les interfaces collées dans le LVL en étudiant l’influence de l’orientation des plis à cette même interface ;- Étudier l’effet de la présence d’un trou sur le comportement mécanique des LVL, première étape pour définir une méthode de dimensionnement des jonctions dans les LVL.En effet, dans la perspective de démontrer l’intérêt des structures bois pour les moyens de transport, il n’est pas possible de se limiter à la caractérisation de matériaux élémentaires et à une stratégie de modélisation éprouvée au niveau du coupon seul. Comme pour la certification des structures aéronautiques, une démarche multiniveaux de type « pyramide des essais » semble pertinente. Aussi, il est primordial de caractériser au mieux le comportement du LVL. Les essais sur éprouvettes trouées ont été choisis, car ils sont utilisés dans de nombreux domaines et n’ont pratiquement pas été étudiés dans les contreplaqués. De plus, ils sont un premier pas vers la caractérisation de jonctions boulonnées et d’assemblages plus complexes. Au travers de ces essais, de nombreuses similitudes, mais aussi des différences significatives ont été observées entre le LVL et les matériaux composites synthétiques. Des modèles numériques élémentaires, s’inspirant de modèles de matériaux composites, ont aussi été proposés dans ces travaux pour appréhender le comportement mécanique spécifique du LVLThis thesis is part of the "BOOST" project (an acronym for "le BOis pOur les STructures des véhicules") funded by the French National Research Agency (ANR). This is a Collaborative Research Project between ICA (Institut Clément Ader) in Toulouse and LaBoMaP (LaBoratoire des Matériaux et Procédés) in Cluny.Wood is a local, renewable resource with a very low carbon footprint. Widely used in aeronautics but also in automobiles as a working structure in the past, its reuse today is becoming a challenge for the bioeconomy (Mair-Bauernfeind et al., 2020; Skullestad et al., 2016). In this field, recent work shows that wood is a "credible" material for the substitution of metallic materials in vehicle structures (Baumann et al., 2020).Previous results from the Institut Clément Ader demonstrate excellent mechanical qualities of wood, and in particular plywood combined with metal or composite skins in static, impact, and crash tests (Guélou, 2021; Susainathan, 2017). For its part, LaBoMaP has developed a method for optically identifying the fiber orientation of each peeled ply making up plywood (Duriot, 2021; Viguier et al., 2018). The scientific objective of this thesis is therefore to:- Characterize poplar LVLs, while characterizing the effect of yarn slopes, the influence of the number of plies, and other LVL-specific characteristics;- Characterize bonded interfaces in LVL, studying the influence of ply orientation at the same interface;- Study the effect of the presence of a hole in the mechanical behavior of LVLs, the first step towards defining a method for dimensioning junctions in LVLs.Indeed, to demonstrate the value of wood structures for the transport industry, it is not possible to limit ourselves to elementary material characterization and elementary modeling strategy. As with the certification of aeronautical structures, a multi-level "test pyramid" approach seems appropriate. It is therefore essential to characterize LVL behavior as accurately as possible. Testing on open-hole specimens was chosen because it is used in many fields and has hardly been studied in plywood or LVL. In addition, they are a first step towards characterizing bolted joints and more complex assemblies. Through these tests, many similarities and significant differences were observed between LVL and synthetic composite materials. Elementary numerical models, inspired by composite material models, were also proposed in this work to apprehend the specific mechanical behavior of LVL
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Verdade, João Filipe Silva. "Comportamento à fadiga em modo I usando o ensaio Double Cantilever Beam modificado". Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/17446.
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Mestrado em Engenharia MecânicaA delaminagem é um dos modos de rutura mais frequentes dos laminados compósitos, e que é geralmente tratado no âmbito da Mecânica da Fratura. Tem havido recentemente interesse crescente na caraterização do comportamento à delaminagem sob fadiga. O primeiro objetivo deste trabalho foi adaptar a máquina de baixo custo desenvolvida no Departamento de Engenharia Mecânica da Universidade de Aveiro à realização de ensaios de delaminagem sob fadiga em modo I. O segundo objetivo foi realizar alguns ensaios de laminado carbono/epóxido iniciando assim um estudo mais alargado de longo prazo. Para isso recorreu-se a ensaios Double Cantilever Beam (DCB) modificados sob deslocamentos cíclicos impostos. Os resultados obtidos foram analisados no quadro da bem conhecida Lei de Paris, que relaciona a taxa de propagação da fenda com a variação da taxa de libertação de energia de deformação. Apesar de serem ainda escassos para tirar conclusões seguras, os resultados indicam um comportamento à fadiga complexo, muito influenciado pelo fenómeno da ponte de fibras.
Delamination is one of the most common damage modes of laminated composites. It is usually analyzed within the scope of Fracture Mechanics. Recently, there has been growing interest in the characterization of fatigue driven delamination. The main objective of the present work was to study the mode I delamination under fatigue of carbon/epoxy laminates through modified Double Cantilever Beam (DBC) tests under imposed cyclic displacements. The tests were conducted on a low cost machine developed at the Department of Mechanical Engineering of the University of Aveiro. The results proved to be consistent with well-known Paris law, which relates the crack propagation rate with the variation of the strain-energy release rate. Though scarce to draw definitive conclusions, the present results indicate a complex fatigue behavior, which is strongly influenced by fiber bridging.
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Majeed, Moiz, i Teja Geesala Rahitya Venkata. "Characterization of thin laminate interface by using Double Cantilever Beam and End Notched Flexure tests". Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-20852.
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This thesis is intended to identify the mode I and mode II fracture toughness to characterize the thin laminate interface by using the Double Cantilever Beam test (DCB) and End Notched Flexure test (ENF). This study’s thin laminate was Polyethylene Terephthalate and Low-Density Polyethylene (PET-LDPE), which is mostly used by packaging industries in the manufacturing of packages to store liquid food. As PET-LDPE film is very flexible and difficult to handle, DCB and ENF tests cannot be performed directly so, sheet metal (Aluminium) was used as carrier material. PET-LDPE film is placed between two aluminum plates to reduce the flexibility and perform the tests. Therefore, the Aluminium plate was also studied to find the constitutive parameters (young’s modulus (E) and mixed hardening parameters (Plastic properties)) under the tensile test and three-point bending test. From the test response, energy release rate calculation has been done for different Pre-crack lengths to validate the DCB and ENF experimental setup, study the different Pre-crack lengths, and characterize the laminate interface. Finite Element simulation (FE simulation) for those tests were carried out in AbaqusTM2020. When needed, the force versus displacement response from FE simulation was optimized against experimental response to find the required constitutive parameters (Young’s modulus, Hardening parameters, and PET-LDPE material properties). Implementing of optimization algorithm and automated simulation has been done with the help of MATLAB code. In contrast, MATLAB works as a server, and Abaqus works as a client and connected two interfaces to run the optimization. The results obtained from experiments and FE simulations were compared to the results found in the literature.
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Liswell, Brian P. "Exploration of Wood DCB Specimens Using Southern Yellow Pine for Monotonic and Cyclic Loading". Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/9955.
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The primary direction of this thesis was towards exploring qualitative and quantitative characteristics necessary for refining and understanding the flat wood double cantilever beam (DCB) as a valid means for testing Mode I fracture energy in wood adhesive bonds. Southern yellow pine (SYP) adherends were used with epoxy and phenol formaldehyde (PF) impregnated films, providing two systems with different characteristics for investigation.
An adhesive penetration analysis was performed for both the epoxy and PF bonds. The PF penetration into the SYP was shown to be relatively shallow. The epoxy penetration was shown to be deeper. Epoxy-SYP DCBs were quasi-statically tested with varying widths (10 mm, 15 mm, and 20 mm), showing decreases in scatter of critical and arrest strain energy release rates, GIc and GIa, with increases in specimen width. Quasi-static fracture testing was also performed on PF SYP-DCBs, showing much higher critical and arrest fracture energy values than the epoxy-SYP DCBs, indicating that deep adhesive penetration is not necessarily a requisite for higher Mode I fracture energy values.
Grain distribution influences were computationally investigated because of the stiffness difference between latewood and earlywood growth and the grain angle along the length of the beams. The grain angle and the stiffness difference between latewood and earlywood growth caused the effective stiffness, (ExxI)eff, to vary along the length of the beam. The effective stiffness variation caused variations in the beam's ability to receive and store strain energy, complicating and confounding determination of experimental results.
Cyclic loading tests were performed on PF-SYP DCB's. The cycle frequency was 3Hz, with a valley to peak load ratio of R = 0.5. Specimen softening was observed with cycling, with re-stiffening occurring with crack growth. Contrary to expectations, specimen compliance occasionally decreased with small crack extensions. A toughening mechanism was frequently observed, whereby subsequent crack lengths required more cycles to failure than the previous crack length. Monotonically extending the crack length far from the fatigued region created a fresh crack that did not show the toughened behavior. But toughening did resume with subsequent crack lengths.Master of Science
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Guan, Youliang. "Crack path selection and shear toughening effects due to mixed mode loading and varied surface properties in beam-like adhesively bonded joints". Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/24905.
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Structural adhesives are widely used with great success, and yet occasional failures can occur, often resulting from improper bonding procedures or joint design, overload or other detrimental service situations, or in response to a variety of environmental challenges. In these situations, cracks can start within the adhesive layer or debonds can initiate near an interface. The paths taken by propagating cracks can affect the resistance to failure and the subsequent service lives of the bonded structures. The behavior of propagating cracks in adhesive joints remains of interest, including when some critical environments, complicated loading modes, or uncertainties in material/interfacial properties are involved. From a mechanics perspective, areas of current interest include understanding the growth of damage and cracks, loading rate dependency of crack propagation, and the effect of mixed mode fracture loading scenarios on crack path selection. This dissertation involves analytical, numerical, and experimental evaluations of crack propagation in several adhesive joint configurations. The main objective is an investigation of crack path selection in adhesively bonded joints, focusing on in-plane fracture behavior (mode I, mode II, and their combination) of bonded joints with uniform bonding, and those with locally weakened interfaces.
When removing cured components from molds, interfacial debonds can sometimes initiate and propagate along both mold surfaces, resulting in the molded product partially bridging between the two molds and potentially being damaged or torn. Debonds from both adherends can sometimes occur in weak adhesive bonds as well, potentially altering the apparent fracture behavior. To avoid or control these multiple interfacial debonding, more understanding of these processes is required. An analytical model of 2D parallel bridging was developed and the interactions of interfacial debonds were investigated using Euler-Bernoulli beam theory. The numerical solutions to the analytical results described the propagation processes with multiple debonds, and demonstrated some common phenomena in several different joints corresponding to double cantilever beam configurations. The analytical approach and results obtained could prove useful in extensions to understanding and controlling debonding in such situations and optimization of loading scenarios.
Numerical capabilities for predicting crack propagation, confirmed by experimental results, were initially evaluated for crack behavior in monolithic materials, which is also of interest in engineering design. Several test cases were devised for modified forms of monolithic compact tension specimens (CT) were developed. An asymmetric variant of the CT configuration, in which the initial crack was shifted to two thirds of the total height, was tested experimentally and numerically simulated in ABAQUS®, with good agreement. Similar studies of elongated CT specimens with different specimen lengths also revealed good agreement, using the same material properties and cohesive zone model (CZM) parameters. The critical specimen length when the crack propagation pattern abruptly switches was experimentally measured and accurately predicted, building confidence in the subsequent studies where the numerical method was applied to bonded joints.
In adhesively bonded joints, crack propagation and joint failure can potentially result from or involve interactions of a growing crack with a partially weakened interface, so numerical simulations were initiated to investigate such scenarios using ABAQUS®. Two different cohesive zone models (CZMs) are applied in these simulations: cohesive elements for strong and weak interfaces, and the extended finite element method (XFEM) for cracks propagating within the adhesive layer. When the main crack approaches a locally weakened interface, interfacial damage can occur, allowing for additional interfacial compliance and inducing shear stresses within the adhesive layer that direct the growing crack toward the weak interface. The maximum traction of the interfacial CZM appears to be the controlling parameter. Fracture energy of the weakened interface is shown to be of secondary importance, though can affect the results when particularly small (e.g. 1% that of the bulk adhesive). The length of the weakened interface also has some influence on the crack path. Under globally mixed mode loadings, the competition between the loading and the weakened interface affects the shear stress distribution and thus changes the crack path. Mixed mode loading in the opposite direction of the weakened interface is able to drive the crack away from the weakened interface, suggesting potential means to avoid failure within these regions or to design joints that fail in a particular manner.
In addition to the analytical and numerical studies of crack path selection in adhesively bonded joints, experimental investigations are also performed. A dual actuator load frame (DALF) is used to test beam-like bonded joints in various mode mixity angles. Constant mode mixity angle tracking, as well as other versatile loading functions, are developed in LabVIEW® for use with a new controller system. The DALF is calibrated to minimize errors when calculating the compliance of beam-like bonded joints. After the corrections, the resulting fracture energies ( ) values are considered to be more accurate in representing the energy released in the crack propagation processes. Double cantilever beam (DCB) bonded joints consisting of 6061-T6 aluminum adherends bonded with commercial epoxy adhesives (J-B Weld, or LORD 320/322) are tested on the DALF. Profiles of the values for different constant mode mixity angles, as well as for continuously increasing mode mixity angle, are plotted to illustrate the behavior of the crack in these bonded joints.
Finally, crack path selection in DCB specimens with one of the bonding surfaces weakened was studied experimentally, and rate-dependency of the crack path selection was found. Several contamination schemes are attempted, involving of graphite flakes, silicone tapes, or silane treatments on the aluminum oxide interfaces. In all these cases, tests involving more rapid crack propagation resulted in interfacial failures at the weakened areas, while slower tests showed cohesive failure throughout. One possible explanation of this phenomenon is presented using the rate-dependency of the yield stress (commonly considered to be corresponding to the maximum traction) of the epoxy adhesives. These experimental observations may have some potential applications tailoring adhesive joint configurations and interface variability to achieve or avoid particular failure modes.Ph. D.
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Fontes, Joel da Silva. "Aplicação da correlação digital de imagem ao estudo da fratura em modo I de ligações coladas". Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22495.
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Mestrado em Engenharia MecânicaAs ligações coladas estão a ter utilização crescente em aplicações estruturais devido às vantagens que têm relativamente a formas tradicionais de ligação, como as ligações aparafusadas e rebitadas. Todavia, subsistem incertezas acerca do comportamento das ligações coladas, que por isso continuam a ser objeto de vários trabalhos de investigação. Esta dissertação incidiu sobre o comportamento à fratura em modo I de ligações de substratos de aço colados com adesivo epóxido. O objetivo principal foi desenvolver e avaliar uma nova forma de aplicação da correlação digital de imagem à monitorização da propagação da fenda no ensaio Double Cantilever Beam (DCB). A técnica proposta baseia-se na medição das extensões nos substratos e, potencialmente, permite a caraterização mais completa e rigorosa do comportamento à fratura. Apesar de coerentes, os resultados obtidos foram afetados pelo ruído nas medições da correlação digital de imagem. São, portanto, necessários melhoramentos na técnica proposta, alguns dos quais foram já identificados e deverão reduzir significativamente os referidos níveis de ruído.
Adhesive joints are finding increasing structural applications, because of their advantages over traditional joining methods e.g. bolted and riveted joints. However, uncertainties remain about the behavior of adhesive joints, which thus continue to be the subject of considerable research. This dissertation studied the mode I fracture behavior of steel substrates bonded by an epoxy adhesive. The main objective was to develop and assess a new form of applying the digital image correlation to crack propagation monitoring in Double Cantilever Beam (DCB) tests. The technique proposed is based on substrate strain measurements and has the potential of enabling a more complete and accurate characterization of the fracture behavior. Despite being coherent, the results obtained were affected by noise levels in digital image correlation measurements. Improvements are therefore needed to the technique proposed, some of which were already identified and should reduce significantly the aforementioned noise.
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Budhe, Sandip Rudha. "Effect of pre-bond moisture on the static and fatigue behaviour of bonded joints between CFRP laminates for structural repairs". Doctoral thesis, Universitat de Girona, 2014. http://hdl.handle.net/10803/283567.
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In recent years, the use of composite materials in the aeronautic, automotive, marine construction, etc. has increased significantly. Hence, there is an increasing need for repair technologies on primary structural components, as replacing a damaged component by a new one is not cost effective in many cases. The composite structures experience damage in service that comes from accidental impacts, mechanical stresses, environmental factors (moisture and temperature), etc. Thus, maintenance and repair is the concern of the end users as well as of the manufacturers. Suitable material systems and controlled curing conditions are essential to fabricate reliable repairs. In this work, the effect of pre-bond moisture is analyzed for co-bonded adhesive joints subjected to static and fatigue loads. Specimens with three levels of pre-bond moisture (0%, 0.33% and 1.25%) and two different adhesive films (F1, F2) have been used in the analysisDurant els últims anys, la utilització de materials compòsits en la indústria aeronàutica, automoció, construcció marina, etc. ha tingut un gran creixement. Es per aquesta raó, que cada vegada té més importància el desenvolupament de mètodes per a la seva reparació, i especialment la definició mètodes de reparació en components que realitzen una funció estructural, doncs la substitució del component no és econòmicament viable en molts dels casos. És un fet conegut, que les estructures de material compòsit en condicions de servei pateixen danys provocats per impactes accidentals, tensions mecàniques, efectes ambientals (humitat i temperatura), etc. Per tant, el manteniment i la reparació d’aquestes estructures són considerats processos de vital importància per a l’usuari final i també per als fabricants. Una bona tria dels materials, així com un bon control dels processos de curat, tenen un gran efecte en l’obtenció de reparacions fiables. En aquest treball s’ha analitzat l’efecte la l’absorció de la humitat en el substrat abans del procés de curat en unions co-encolades sotmeses a càrregues estàtiques i de fatiga. L’anàlisi s’ha dut a terme amb provetes amb 3 nivells d’absorció d’humitat (0%, 0.33% y 1.25%) i dos tipus d’adhesius laminats (F1 i F2)
Książki na temat "Essai Double Cantilever Beam (DCB)"
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Pavlovskis, Pēteris. Analysis of Two Actual Problems of Interlaminar Fracture Assessment of Layered Composite. RTU Press, 2022. http://dx.doi.org/10.7250/9789934228148.
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Two types of specimens were studied based on applying the nonlinear theory of flexible plates to obtain the interlaminar fracture toughness of layered composites. For a specimen of the thin sub-layer type, a theoretical solution was obtained in relation to the determination of the interlaminar fracture toughness for a mixed II/I mode. The fundamental possibility of using this solution in test practice was confirmed. The application of the nonlinear theory of flexible plates to the well-known standard specimen of the double-cantilever beam (DCB) was studied in more detail. A theoretical solution was obtained, an iterative algorithm for processing test results based on MATLAB code was developed, highly flexible glass fiber reinforced polymer (GFRP) specimens were tested and their comparison with the results of processing according to the ASTM D 5528-01 standard with correction of the linear solution was given.
Części książek na temat "Essai Double Cantilever Beam (DCB)"
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Sun, Chen, Minghua Dai, Liang Ying, Kai Du, Zhigang Chen i Ping Hu. "Experimental and Numerical Simulation on Formability and Failure Behavior of Thermoplastic Carbon Fiber/AL Composite Laminates". W Lecture Notes in Mechanical Engineering, 383–93. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-58006-2_30.
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AbstractCarbon fiber reinforced thermoplastic/aluminum alloy (CFRTP/AL) composite laminates have the advantages of low density, high specific strength, and good fatigue resistance, which is a new type of engineering composite material to realize lightweight vehicle body. Heterogeneous interface delamination failure occurs in the forming process of the fiber metal laminates (FMLs). It is necessary to establish an effective finite element simulation strategy to accurately predict the delamination failure behavior of FMLs. In this work, thermoplastic PA6 continuous carbon fiber/AL FMLs were taken as the research object, and the double cantilever beam (DCB) and the end-notched flexure (ENF) experiments were carried out to determine the basic mechanical parameters between the interlayer interfaces of CFRTP/AL. Furthermore, a numerical simulation model based on ABAQUS software was developed to describe the progressive damage failure behavior of the CRFTP/AL in the forming process by using the equivalent modeling strategy of discontinuous micro-shear, which realized the effective prediction of ply directional damage failure of FMLs on the basis of the S-beam model. The results show that the established damage constitutive model and numerical method coupled with cohesive zone model (CZM) can effectively predict the ply directional damage failure behavior of CFRTP/AL composites during the large deformation forming.
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Meltem Toygar, Evren, i Ahmet Gulakman. "Failure Modes in Fiber Reinforced Composites and Fracture Toughness Testing of FRP". W Advances in Fatigue and Fracture Testing and Modelling. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.99268.
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In this paper, interlaminar fracture behavior of woven-fabric-reinforced glass/epoxy composites has been investigated experimentally and numerically. The mechanical properties of this composite were studied and Mode I (Tensile Opening) DCB (Double Cantilever Beam) tests were performed on Fiber Reinforced Composite (FRP) specimens to determine the delaminating resistance of composite laminates used for structural applications. Techniques for measuring the interlaminar fracture toughness, KIC data of woven-fabric-reinforced glass/epoxy composite materials, are highlighted under the consideration of ASTM Standard D5528–01 and test methods ISO 15024, DIN EN ISO 75-1 and DIN EN ISO 75-3. The obtained test results were apparently consistent with the assumptions of the CCM (Compliance Calibration Method) that was used to obtain the interlaminar critical SERR (strain energy release rate), GIC. Finite element analysis was conducted to validate the closed form solution. The use of obtained mechanical properties data in finite element analyses utilizing fracture mechanics are examined. Results show a good agreement between experimental and numerical solutions.
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Gaona-Tiburcio, Citlalli, Alejandro Lira-Martínez, Marianggy Gomez-Avila, Jesús M. Jaquez-Muñoz, Miguel Angel Baltazar-Zamora, Laura Landa-Ruiz, Demetrio Nieves-Mendoza, Francisco Estupiñan-López i Facundo Almeraya-Calderón. "Delamination and Tensile Effect of Fine z-Binder Reinforced on Fiberglass/Polyester Composite for Aerospace Applications". W Next Generation Fiber-Reinforced Composites - New Insights [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.106927.
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Delamination propagation in laminated composite materials is a common issue that always concerns us when we consider composites for structural purpose. Many possible solutions have been studied; the most famous is the three-dimensional (3D) woven composites materials, which have promising interlaminar fracture resistance but at the cost of increasing density, which for aerospace industry is very important. In this chapter, mode 1 double cantilever beam (DCB) interlaminar fracture toughness tests according to the American Society for Testing and Materials (ASTM) D5528 standard were performed on composite specimens made of E-Glass Saertex 830 g/m2 Biaxial (+/−45°) with Sypol 8086 CCP polyester resin with orthogonal z-axis oriented yarn woven of 0.22 mm diameter nylon monofilament. Four specimens were made with a longitudinal distance between the warp binders of 0.5, 1, 1.5, and 2 cm, respectively. A tensile test according to the ASTM D3039 standard was performed to study how z-binder may affect tensile resistance. The results show a considerable increase in interlaminar fracture toughness, several stress concentrators have been created because of the new yarn and premature failure in the matrix.
Streszczenia konferencji na temat "Essai Double Cantilever Beam (DCB)"
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Sankarasubramanian, Santosh, Jaime Cruz, Kyle Yazzie, Vaasavi Sundar, Vijay Subramanian, Edvin Cetegen, David McCoy i Pramod Malatkar. "High Temperature Interfacial Adhesion Strength Measurement in Electronic Packaging Using the Double Cantilever Beam Method". W ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-67007.
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Advanced microelectronic packages utilize a multitude of materials with dramatically different mechanical properties. Delamination occurring at the interfaces between these materials, due to poor adhesion and/or moisture exposure, is an important failure mode affecting the thermomechanical reliability of the package. The adhesion strength of these interfaces is a critical mechanical property that plays a role in the reliability performance of these packages. A good adhesion strength metrology is required to perform material selection and enable assembly process optimization in order to avoid the need for expensive assembly builds, followed by reliability testing which leads to long development times. This paper discusses the use of the Double Cantilever Beam (DCB) method for characterizing the adhesion strength of interfaces in advanced microelectronic packages at both room and high temperatures. Previous work in this area was focused only on room temperature testing. However, in order to characterize the adhesion strength of these interfaces at elevated temperatures seen during package assembly and reliability testing, an environmental chamber was designed and fabricated to rapidly and uniformly heat the DCB samples for testing at high temperatures. Depending on the interface tested and the testing temperature, DCB samples failed in one of three fail modes: (1) adhesive (at the interface), (2) cohesive (within the adhesive layer), and (3) brittle cracking of the substrate. Two case studies describing high temperature DCB testing on silicon-capillary underfill samples are presented. With adhesive failure being the desired fail mode in order to rank order materials and processes, it was found that for the underfills tested in this study, the DCB samples failed cohesively within the underfill at room temperature but started failing adhesively at temperatures near 150°C. Adhesion strength also showed a clear degradation with temperature. It is suspected that the change in failure mode from cohesive to adhesive with increasing temperature is due to competing trends of degradation in cohesive strength of the underfill versus degradation in adhesive strength of the interface with temperature.
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XU, WU, i JIANCAN DING. "CLOSED-FORM J-INTEGRAL AND ITS APPLICATIONS FOR MEASUREMENT OF MODE I INTERLAMINAR FRACTURE TOUGHNESS OF COMPOSITES". W Thirty-sixth Technical Conference. Destech Publications, Inc., 2021. http://dx.doi.org/10.12783/asc36/35925.
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Due to the interlaminar properties of composites are low, delamination is one of the major failure modes. It threatens the safety of composite structure subjected to out-of-plane static and especially impact loadings. High interlaminar fracture toughness is demanded in the society where composite structures are widely used. However, for tough material, large deformation may occur in the determination of the interlaminar fracture toughness when using the double cantilever beam (DCB) test. Therefore, accurate determination of the fracture toughness of tough material and dynamic loading is very challenging under large deformation. J-integral is an important parameter in fracture mechanics. It’s equivalent to energy release rate under monotonic loading and widely used in the determination of interlaminar fracture toughness of composites. In this paper, it is used to determine the fracture toughness for composite DCB under large deformation and wedge-insert double cantilever beam (WDCB) test, which is widely used to determine the dynamic interlaminar fracture toughness. Exact and closed form nonlinear J-integrals are derived for the largely deformed DCB and WDCB. Compared with the alternative data reduction methods for determining interlaminar fracture toughness, the J- integral method is more accurate. In addition, the J-integral method is simple and promising, since it is unnecessary to measure the crack length in the tests.
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LI, GANG, i GUILLAUME RENAUD. "EVALUATION OF COMPOSITE DCB DELAMINATION GROWTH BY COMBINING EXPERIMENTAL DATA AND NUMERICAL ANALYSIS". W Proceedings for the American Society for Composites-Thirty Seventh Technical Conference. Destech Publications, Inc., 2022. http://dx.doi.org/10.12783/asc37/36369.
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A study of quasi-static mode I delamination in a laminated unidirectional composite double cantilever beam (DCB) configuration was conducted experimentally and numerically. A two-dimensional (2D) finite element (FE) correction method that consisted of a series of analyses of the DCB compliances at different delamination lengths was conducted to establish an analytical correlation between the delamination length and the DCB opening compliance. This analytical correlation was then used to determine the delamination length provided the experimentally measured compliance. Consequently, the problematic delamination lengths generated from in-situ optical measurement were evaluated and corrected. Also, the fracture resistance curve was updated using the corrected delamination lengths. Good agreement in the loaddisplacement variation was then obtained between the experimental results and the subsequent 2D DCB FE modelling results using cohesive elements. Commentaries on the DCB quasi-static failure analysis and modelling using the cohesive zone modelling technique and the virtual crack closure technique were also provided.
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Ngabonziza, Yves, Claudia Boldrini, Benjamin Liaw, Jackie Li i Feridun Delale. "Damage Self-Diagnosis in Carbon Fiber-Reinforced Composites Under Fatigue Loading". W ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2010. http://dx.doi.org/10.1115/smasis2010-3870.
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An experimental study was conducted to sense interlaminar delamination in carbon-fiber composites utilizing inherent material piezoresistivity. Damage detection was carried out using discrete electrodes mounted on a Double Cantilever Beam (DCB) specimen. The DCB composite specimens were tested for fatigue interlaminar fracture. The traditional two-point probe and four-point probe technique were employed to measure the through-thickness electrical resistance change. Optical marker method was also used to detect interlaminar crack growth. The results show that the two-point probe measurements did not capture effectively the delamination propagation while the four-point probe measurement showed a promising sensing capability in terms of delamination propagation.
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WEEKS, SHAWN, i MICHAEL CZABAJ. "STATIC AND FATIGUE CHARACTERIZATION OF MODE I FRACTURE IN ADHESIVELY BONDED COMPOSITES BASED ON THE J-INTEGRAL APPROACH". W Proceedings for the American Society for Composites-Thirty Eighth Technical Conference. Destech Publications, Inc., 2023. http://dx.doi.org/10.12783/asc38/36708.
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In this work, efforts are made to further develop tests for characterization of mode I quasi-static and fatigue fracture of adhesively bonded composites based on the J-integral approach using the double cantilever beam (DCB) test. This work will address the few remaining challenges that must be resolved before standardization of these test methods. Specifically presented are the attempts to: 1) establish a robust procedure for measuring JI using specimen arm rotation and the applied load, 2) determine specimen geometry that would enable accurate characterization of the traction separation law (TSL) during DCB testing, and 3) develop a protocol for J-controlled fatigue testing without explicit knowledge of crack extension.
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Shahani, Amir Reza, i Mohammad Reza Amini Fasakhodi. "Analytical Modeling of Dynamic Crack Propagation in DCB Specimens". W ASME 2009 Pressure Vessels and Piping Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/pvp2009-78055.
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An analytical solution via the beam theory considering shear deformation effects is developed to solve the static and dynamic fracture problem in a bounded medium such as DCB (Double Cantilever Beam) specimen. In the static case, the stress intensity factor (SIF) is derived at the crack tip through the compliance approach for fixed displacement conditions. In the dynamic case, the energy balance criterion is employed to obtain the equation of motion for a running crack and the problem is solved supposing quasi-static crack propagation. Finally, a closed form relation for the crack propagation velocity versus specimen parameters and crack growth resistance of the material is found. Therefore, the effects of various parameters are investigated on the crack growth velocity. It is shown that the reacceleration of crack growth appears when the crack tip approaches the end of specimen under fixed displacement loading. The predicted results are compared with those cited in the literature and a good agreement is observed. It is seen that shear deformation effects are more significant when the small values of a0/h is considered in the analysis.
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Vishe, Nilesh J., Sameer B. Mulani i Samit Roy. "Self-Healing of Fatigue Delamination in Thermoset Composites Using Thermoplastic Healants". W ASME 2023 Aerospace Structures, Structural Dynamics, and Materials Conference. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/ssdm2023-108435.
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Abstract In this study, fatigue testing under mode-I loading was carried out on double cantilever beam (DCB) specimens, and subsequent healing of the delamination was investigated. Due to the susceptibility of laminated composites to delamination, fatigue delamination is one of the crucial damage modes in laminated composites that may result in catastrophic structural failure. Hence, it is necessary to investigate and quantify the delamination crack growth behavior due to fatigue loading and explore methods to heal the delamination. Therefore, DCB specimens of a carbon fiber-reinforced thermoset polymer (CFRP) composite containing thermoplastic healants were manufactured. The main objective of using thermoplastic healants, i.e., polycaprolactone and shape memory polymer, was to close and then heal the fatigue cracks. In-situ self-healing was achieved by activating macro fiber composite (MFC) actuators bonded to the DCB specimen, where the high-frequency vibration of the actuator provides the heat necessary to close the cracks using thermoplastic healants.
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Pal, Joydeep, Chandan Mukhopadhyay i Ajit K. Roy. "Cracking of Alloy C-276 in an Acidic Environment". W ASME 2007 Pressure Vessels and Piping Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/pvp2007-26429.
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Austenitic Alloy C-276 has been identified as a structural material for application in hydrogen generation using nuclear heat. Fracture-mechanics-based pre-cracked and wedge-loaded double-cantilever-beam (DCB) specimens have been tested in an acidic solution at ambient temperature for 15 and 30 days. Three levels of initial stress intensity factors (K1) were used to determine crack propagation following exposure of the DCB specimens to the test environment. The results indicate that the magnitude of K1 was substantially reduced after testing, the extent of reduction being more pronounced with specimens tested for a longer duration. Three different types of failures namely, striations, cleavage and ductile, respectively were noted in the tested specimens, as determined by scanning electron microscopy.
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SHAH, ADITYA, i RANI W. SULLIVAN. "OUT-OF-PLANE DISPLACEMENTS OF COMPOSITE DCB SPECIMENS USING EMBEDDED OPTICAL FIBER STRAINS". W Proceedings for the American Society for Composites-Thirty Seventh Technical Conference. Destech Publications, Inc., 2022. http://dx.doi.org/10.12783/asc37/36397.
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The use of polymer matrix composite materials in primary load-bearing structures has increased in the aerospace industry primarily due to their high strength-to-weight ratios and stiffnesses. However, composites are susceptible to delamination due to their low interlaminar fracture resistance, which can result in stiffness degradation, thereby decreasing the structural integrity of the part. Strains obtained from embedded optical fibers can be used to detect and monitor damages. Optical fiber strain sensors are lightweight, easy to embed, and offer higher resolution and data acquisition rates. In this study, double cantilever beam (DCB) specimens fabricated from Hexcel IM7/8552 carbon/epoxy prepreg are embedded with optical fibers. Outof- plane displacements of the DCB specimens were calculated using optical fiber strains and show excellent agreement with deflections measured using the DIC system.
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Ngabonziza, Yves, Hale Ergun, Regina Kuznetsova, Jackie Li, Benjamin Liaw i Feridun Delale. "Structural Self-Diagnosis for Damage in Carbon-Fiber Reinforced Composites". W ASME 2008 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2008. http://dx.doi.org/10.1115/smasis2008-365.
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Composite structural self-diagnostic (CSSD) technology has been tested to detect the mechanical damages in carbon-fiber reinforced polymer-matrix composites. In order to characterize the self-sensing technique for damage detection, discrete electrodes were mounted on Double-Cantilever-Beam (DCB). Results on mechanical properties with corresponding electrical resistance changes of the CFRC specimens are presented in this paper. The lay-up configuration of the composite specimens is [06/Teflon/06]T. In addition, acoustic emission was also used to corroborate the CSSD results.