Academic literature on the topic 'Cohesive zone law'
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Journal articles on the topic "Cohesive zone law"
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Yuan, Huang, Guoyu Lin, and Alfred Cornec. "Verification of a Cohesive Zone Model for Ductile Fracture." Journal of Engineering Materials and Technology 118, no. 2 (April 1, 1996): 192–200. http://dx.doi.org/10.1115/1.2804886.
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In the present paper, ductile crack growth in an aluminium alloy is numerically simulated using a cohesive zone model under both plane stress and plane strain conditions for two different fracture types, shear and normal modes. The cohesive law for ductile fracture consists of two parts—a specific material’s separation traction and energy. Both are assumed to be constant during ductile fracture (stable crack growth). In order to verify the assumed cohesive law to be suitable for ductile fracture processes, experimental records are used as control curves for the numerical simulations. For a constant separation traction, determined experimentally from tension test data, the corresponding cohesive energy was determined by finite element calculations. It is confirmed that the cohesive zone model can be used to characterize a single ductile fracture mode and is roughly independent of stable crack extention. Both the cohesive traction and the cohesive fracture energy should be material specific parameters. The extension of the cohesive zone is restricted to a very small region near the crack tip and is in the order of the physical fracture process. Based on the present observations, the cohesive zone model is a promising criterion to characterize ductile fracture.
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Kim, Kyungmok. "Creep–rupture model of aluminum alloys: Cohesive zone approach." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, no. 8 (July 10, 2014): 1343–47. http://dx.doi.org/10.1177/0954406214543413.
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In this article, a creep–rupture model of aluminum alloys is developed using a time-dependent cohesive zone law. For long-term creep rupture, a time jump strategy is used in a cohesive zone law. Stress–rupture scatter of aluminum alloy 4032-T6 is fitted with a power law form. Then, change in the slope of a stress-rupture line is identified on a log–log scale. Implicit finite element analysis is employed with a model containing a cohesive zone. Stress–rupture curves at various given temperatures are calculated and compared with experimental ones. Results show that a proposed method allows predicting creep–rupture life of aluminum alloys.
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Cazes, Fabien, Anita Simatos, Michel Coret, Alain Combescure, and Anthony Gravouil. "Cracking Cohesive Law Thermodynamically Equivalent to a Non-Local Damage Model." Key Engineering Materials 385-387 (July 2008): 81–84. http://dx.doi.org/10.4028/www.scientific.net/kem.385-387.81.
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This paper deals with the transition from a localized damage state to crack formation. Several attempts have already been made in this field. Our approach is in the continuity of studies where thermodynamic considerations lead to the definition of an equivalent crack concept. The main idea consists in replacing a damaged localized zone by a crack in order to recover the same amount of dissipated energy. On the one hand, a nonlocal model is used to modelize accurately localized damage. On the other hand, an elastic model which authorizes the formation of a crack described by a cohesive zone model is used. This cohesive zone model is defined thermodynamically in order to be in concordance with the damage model. The method allows obtaining the cohesive zone model traction curve from the knowledge of the nonlocal damage model solution. The numerical implementation is done using a Lagrangian multiplier that ensures the energetic equivalence between both models.
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Shintaku, Yuichi, Kenjiro Terada, and Seiichiro Tsutsumi. "Anisotropic Damage Constitutive Law for Cleavage Failure in Crystalline Grain by Cohesive Zone Model." QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY 35, no. 2 (2017): 165s—168s. http://dx.doi.org/10.2207/qjjws.35.165s.
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Pandya, K. C., and J. G. Williams. "Cohesive zone modelling of crack growth in polymers Part 1 –Experimental measurement of cohesive law." Plastics, Rubber and Composites 29, no. 9 (September 2000): 439–46. http://dx.doi.org/10.1179/146580100101541274.
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Yuan, Huang, and Xiao Li. "Effects of the cohesive law on ductile crack propagation simulation by using cohesive zone models." Engineering Fracture Mechanics 126 (August 2014): 1–11. http://dx.doi.org/10.1016/j.engfracmech.2014.04.019.
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Roy, Samit, and Yong Wang. "Analytical Solution for Cohesive Layer Model and Model Verification." Polymers and Polymer Composites 13, no. 8 (November 2005): 741–52. http://dx.doi.org/10.1177/096739110501300801.
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The objective of this work was to find an analytical solution to the stresses in the cohesive damage zone and the damage zone length at the interface between a fibre reinforced polymer (FRP) plate and concrete substrate. Analytical solutions have been derived to predict the stress in the cohesive layer when considering the deformation in the stiff substrate. A two-dimensional cohesive layer constitutive model with a prescribed traction-separation (stress-strain) law was constructed using a modified Williams' approach, and analytical solutions derived for the elastic zone as well as the damage zone. Detailed benchmark comparisons of analytical results with finite element predictions for a double cantilever beam specimen were performed for model verification, and issues related to cohesive layer thickness were investigated. It was observed that the assumption of a rigid substrate in analytical modelling can lead to inaccurate analytical prediction of the cohesive damage zone length.
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Fager, Leif-Olof, and J. L. Bassani. "Stable Crack Growth in Rate-Dependent Materials With Damage." Journal of Engineering Materials and Technology 115, no. 3 (July 1, 1993): 252–61. http://dx.doi.org/10.1115/1.2904215.
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A cohesive zone model of the Dugdale-Barenblatt type is used to investigate crack growth under small-scale-creep/damage conditions. The material inside the cohesive zone is described by a power-law viscous overstress relation modified by a one-parameter damage function of the Kachanov type. The stress and displacement profiles in the cohesive zone and the velocity dependence of the fracture toughness are investigated. It is seen that the fracture toughness increases rapidly with the velocity and asymptotically approaches the case that neglects damage.
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Scheel, Johannes, Alexander Schlosser, and Andreas Ricoeur. "The J-integral for mixed-mode loaded cracks with cohesive zones." International Journal of Fracture 227, no. 1 (November 23, 2020): 79–94. http://dx.doi.org/10.1007/s10704-020-00496-6.
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AbstractThe J-integral quantifies the loading of a crack tip, just as the crack tip opening displacement (CTOD) emanating from the cohesive zone model. Both quantities, being based on fundamentally different interpretations of cracks in fracture mechanics of brittle or ductile materials, have been proven to be equivalent in the late 60s of the previous century, however, just for the simple mode-I loading case. The relation of J and CTOD turned out to be uniquely determined by the constitutive law of the cohesive zone in front of the physical crack tip. In this paper, a J-integral vector is derived for a mixed-mode loaded crack based on the cohesive zone approach, accounting for the most general case of a mode-coupled cohesive law. While the$$J_1$$J1-coordinate, as energy release rate of a straight crack extension, is uniquely related to the cohesive potential at the physical crack tip and thus to the CTOD, the$$J_2$$J2-coordinate depends on the solution of the specific boundary value problem in terms of stresses and displacement gradients at the cohesive zone faces. The generalized relation is verified for the Griffith crack, employing solutions of the Dugdale crack based on improved holomorphic functions.
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Huang, Xiao Hui, Wen Guang Liu, Guo Qun Zhao, and Xin Hai Zhao. "An Investigation into the Fracture Mechanical Behavior of Bone Cement: Simulation Using Cohesive Zone Models (CZMs)." Advanced Materials Research 156-157 (October 2010): 1658–64. http://dx.doi.org/10.4028/www.scientific.net/amr.156-157.1658.
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In this investigation, we propose a new concept to embed cohesive zone into the continuum structure of bone cement, an example of brittle material, in investigating the mechanical behavior and fracture mechanism and to predict the fracture which elastic fracture mechanics (EFM) is unable to. Four finite element (FE) models with embedded cohesive zones for the simulations of tensile, compression, double shear and 3-point bending tests have been implemented. Cohesive zones (CZ) are embedded at high risks of fracture with orientations determined by fracture mode. A bilinear cohesive traction-separation law (TSL) is applied. The fracture parameters in traction-separation curve are validated and justified in the simulations to agree well with the force-displacement curves in the four practical tests. Apart from the maximum load, the perpetual safe working load (SWL) in theory also can be predicted by tracing the history of the stiffness degradation of fractured cohesive zone by means of simulation. A distinct advantage of our numerical model is that it is able to extend to investigate the mechanical behavior and fracture mechanism of other brittle materials. The proposed method with embedded cohesive zones in FE models can be introduced to predict the fracture and to forecast the maximum load and safe working load (SWL) of the continuum structure in more complicated loading conditions.
Dissertations / Theses on the topic "Cohesive zone law"
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Salih, Sarmed. "Rate-dependent cohesive-zone models for fracture and fatigue." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/ratedependent-cohesivezone-models-for-fracture-and-fatigue(d8bfee97-1a75-4418-8916-b5a7cf8cdfd9).html.
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Despite the phenomena of fracture and fatigue having been the focus of academic research for more than 150 years, it remains in effect an empirical science lacking a complete and comprehensive set of predictive solutions. In this regard, the focus of the research in this thesis is on the development of new cohesive-zone models for fracture and fatigue that are afforded an ability to capture strain-rate effects. For the case of monotonic fracture in ductile material, different combinations of material response are examined with rate effects appearing either in the bulk material or localised to the cohesive-zone or in both. The development of a new rate-dependent CZM required first an analysis of two existing methods for incorporating rate dependency, i.e.either via a temporal critical stress or a temporal critical separation. The analysis revealed unrealistic crack behaviour at high loading rates. The new rate-dependent cohesive model introduced in the thesis couples the temporal responses of critical stress and critical separation and is shown to provide a stable and realistic solution to dynamic fracture. For the case of fatigue, a new frequency-dependent cohesive-zone model (FDCZM) has been developed for the simulation of both high and low-cycle fatigue-crack growth in elasto-plastic material. The developed model provides an alternative approach that delivers the accuracy of the loading-unloading hysteresis damage model along with the computational efficiency of the equally well-established envelope load-damage model by incorporating a fast-track feature. With the fast-track procedure, a particular damage state for one loading cycle is 'frozen in' over a predefined number of cycles. Stress and strain states are subsequently updated followed by an update on the damage state in the representative loading cycle which again is 'frozen in' and applied over the same number of cycles. The process is repeated up to failure. The technique is shown to be highly efficient in terms of time and cost and is particularly effective when a large number of frozen cycles can be applied without significant loss of accuracy. To demonstrate the practical worth of the approach, the effect that the frequency has on fatigue crack growth in austenitic stainless-steel 304 is analysed. It is found that the crack growth rate (da/dN) decreases with increasing frequency up to a frequency of 5 Hz after which it levels off. The behaviour, which can be linked to martensitic phase transformation, is shown to be accurately captured by the new FDCZM.
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Sarrado, Molina Carlos. "Experimental characterization and numerical simulation of composite adhesive joints using the cohesive zone model approach." Doctoral thesis, Universitat de Girona, 2015. http://hdl.handle.net/10803/384001.
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The present thesis aims at developing robust numerical and experimental methods for the simulation of composite adhesive joints. Firstly, a new method for the experimental characterization of adhesive joints is presented. The proposed method widens the range of applicability of the existing methods at the same time that lowers the uncertainty of the results. By means of this method, a critical study on the validity of the existing experimental methods is presented, as well as the thorough characterization of an adhesive in terms of the cohesive laws of the material. The experimental evidences are analyzed to obtain a guideline for the simulation of adhesive joints and a formulation of a new cohesive elements is presented. The proposed formulation allows the simulation of the elastic response, damage and failure of adhesive layers by using experimentally measurable material properties, with no further calibrations required.L’objectiu de la present tesi és el desenvolupament de mètodes numèrics i experimentals robustos per a la simulació de la fractura en unions adhesives de material compòsit. En primer lloc es presenta un nou mètode per a la caracterització experimental d’unions adhesives que amplia el rang d’aplicació dels mètodes existents i en disminueix la incertesa. A partir d’aquí, es realitza un estudi crític sobre la idoneïtat dels mètodes de caracterització d’unions adhesives existents i es presenta la caracterització exhaustiva d’un adhesiu en termes de la llei cohesiva del material. Les evidencies experimentals obtingudes s’analitzen per tal de proporcionar les directrius necessàries per a la simulació d’unions adhesives i es presenta la formulació d’un nou element cohesiu per modelar la resposta elàstica, el dany i la fallada d’adhesius. El model proposat permet l’ús de propietats del material mesurables experimentalment, sense la necessitat de dur a terme ajustaments o calibratges addicionals.
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Bahadursha, Venkata Rama Lakshmi Preeethi. "Tearing of Styrene Butadiene Rubber using Finite Element Analysis." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1431029910.
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Shanmugam, Venkateswaran. "Efficient Risk Assessment Using Probability of Fracture Nomographs." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1322059829.
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Taleb, Ali Mahfoudh. "Effet des défauts d'adhésion sur la résistance mécanique des assemblages collés." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0061/document.
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Le collage structural est une technique d’assemblage de plus en plus demandée aujourd’hui dans beaucoup de domaines comme l’automobile, l’aéronautique, l’aérospatial et dans d’autres domaines comme la construction, le sport et les loisirs. Cette technique très avantageuse, permet l’assemblage de matériaux semblables ou différents à l’aide d’un adhésif, la réduction importante du poids et la répartition uniforme des charges sur l’assemblage. Malgré ses avantages, le collage souffre encore de quelques inconvénients liés à l’existence de défauts dans les joints de colle. Parmi eux, il existe des défauts qui sont situés à l’interface colle/substrat comme un « kissing bond » ou un mauvais état de surface, qui restent indétectables ou difficilement détectables utilisant les techniques de contrôle non destructives. Donc, afin de prendre en compte l’existence des défauts d’adhésion dans les assemblages collés lors de la phase de conception, il est nécessaire de fournir un modèle analytique capable de prédire la propagation de fissure. Dans cette thèse, un modèle analytique qui prédit la propagation de fissure et qui évalue la résistance effective d’un assemblage collé contenant des défauts d’adhésion a été développé. Un défaut a généralement une géométrie complexe, et une étude générique est difficilement réalisable ce qui nous amène à considérer des géométries de défauts idéales. Le modèle a été vérifié par des expériences réalisées sur des éprouvettes DCB. Des simulations numériques utilisant la méthode de zone cohésive ont été réalisées également pour décrire plus complètement le processus de décohésion et simuler les essais expérimentaux. La dernière partie de ce travail a été dédiée à l’étude de la fissuration des éprouvettes en alliage de titane. Profitant de la collaboration avec Safran et Alphanov, les substrats ont subi un traitement de surface laser en laissant des zones non traitées. Le but de cette partie était de vérifier le modèle analytique proposé avec des configurations plus complexesStructural adhesive bonding has known an increasing use in many fields like aeronautics, aerospace and automotive and other fields like construction and sports. This very advantageous technique allows the assembly of similar or different materials using an adhesive, the significant reduction in weight and a uniform distribution of loads on the assembly. Despite its advantages, the bonding still suffers from some disadvantages related to the existence of defects in the bonded joints. Among them, there are defects that are located at the interface glue / substrate as "kissing bond" or poor surface due to bad surface treatment, which remain undetectable or hardly detectable using non-destructive control techniques. Therefore, in order to take into account the existence of adhesion defects in bonded assemblies during the design phase, it is necessary to provide an analytical model capable of predicting crack propagation and estimate the criticality of a defect. In this thesis, an analytical model that predicts crack propagation and evaluates the effective strength of a bonded assembly containing adhesion defects has been developed. A defect usually has a complex geometry, and a generic study is difficult to achieve, which leads us to consider ideal defect geometries. The model was verified by experiments performed on DCB specimens. Numerical simulations using the cohesive zone method were also performed to more fully describe the decohesion process and to simulate the experimental tests. The last part of this work was devoted to the study of titanium alloy assembly containing patterns. Taking advantage of the collaboration with Safran and Alphanov, the substrates underwent a laser surface treatment leaving untreated areas. The purpose of this part was to check the proposed analytical model with more complex configurations
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Andersson, Lassila Andreas, and Marcus Folcke. "Numerical and experimental analysis of adhesively bonded T-joints : Using a bi-material interface and cohesive zone modelling." Thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-15280.
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With increasing climate change the automotive industry is facing increasing demands regarding emissions and environmental impact. To lower emissions and environmental impact the automotive industry strives to increase the efficiency of vehicles by for example reducing the weight. This can be achieved by the implementation of lightweight products made of composite materials where different materials must be joined. A key technology when producing lightweight products is adhesive joining. In an effort to expand the implementations of structural adhesives Volvo Buses wants to increase their knowledge about adhesive joining techniques. This thesis is done in collaboration with Volvo Buses and aims to increase the knowledge about numerical simulations of adhesively bonded joints. A numerical model of an adhesively bonded T-joint is presented where the adhesive layer is modelled using the Cohesive Zone Model. The experimental extraction of cohesive laws for adhesives is discussed and implemented as bi-linear traction-separation laws. Experiments of the T-joint for two different load cases are performed and compared to the results of the numerical simulations. The experimental results shows a similar force-displacement response as for the results of the numerical simulations. Although there were deviations in the maximum applied load and for one load case there were deviations in the behavior after the main load drop. The deviations between numerical and experimental results are believed to be due to inaccurate material properties for the adhesive, the use of insufficient bi-linear cohesive laws, the occurrence of a combination of adhesive and cohesive fractures during the experiments and dissimilar effective bonding surface areas in the numerical model and the physical specimens.
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Mokashi, Prasad Shrikant. "Numerical modeling of homogeneous and bimaterial crack tip and interfacial cohesive zones with various traction-displacement laws." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1180621217.
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Lucchi, Andrea. "Numerical simulation of low velocity impact on fiber metal laminates." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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The diffusion of composite laminates in aerospace industry has been slowed down by complexity in the prediction of fracture behaviours. In this respect the delamination phenomenon caused by Low-Velocity Impacts has been a critical issue. Several criteria that predict the delamination onset and growth have been analysed. The subsequent study has been focused on Cohesive Zone Models able to predict both initiation and propagation of delamination. Several models that represent the dynamic response of composite structures to impacts have been presented. An explicit FEM has been developed to perform 3D simulations of different layup configurations of Al2024T3 and Woven Carbon Prepreg Laminates subjected to a Low-Velocity Impact. ABAQUS, Dassault Systèmes Simulia Corp. has been employed to perform the numerical simulations. Specific attention is paid to the cohesive failure representing delamination.
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Raghavan, Sathyanarayanan. "Experimental and theoretical study of on-chip back-end-of-line (BEOL) stack fracture during flip-chip reflow assembly." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/54298.
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With continued feature size reduction in microelectronics and with more than a billion transistors on a single integrated circuit (IC), on-chip interconnection has become a challenge in terms of processing-, electrical-, thermal-, and mechanical perspective. Today’s high-performance ICs have on-chip back-end-of-line (BEOL) layers that consist of copper traces and vias interspersed with low-k dielectric materials. These layers have thicknesses in the range of 100 nm near the transistors and 1000 nm away from the transistors close to the solder bumps. In such BEOL layered stacks, cracking and/or delamination is a common failure mode due to the low mechanical and adhesive strength of the dielectric materials as well as due to high thermally-induced stresses. However, there are no available cohesive zone models and parameters to study such interfacial cracks in sub-micron thick microelectronic layers.
This work focuses on developing framework based on cohesive zone modeling approach to study interfacial delamination in sub-micron thick layers. Such a framework is then successfully applied to predict microelectronic device reliability. As intentionally creating pre-fabricated cracks in such interfaces is difficult, this work examines a combination of four-point bend and double-cantilever beam tests to create initial cracks and to develop cohesive zone parameters over a range of mode-mixity. Similarly, a combination of four-point bend and end-notch flexure tests is used to cover additional range of mode-mixity. In these tests, silicon wafers obtained from wafer foundry are used for experimental characterization. The developed parameters are then used in actual microelectronic device to predict the onset and propagation of crack, and the results from such predictions are successfully validated with experimental data. In addition, nanoindenter-based shear test technique designed specifically for this study is demonstrated. The new test technique can address different mode mixities compared to the other interfacial fracture characterization tests, is sensitive to capture the change in fracture parameter due to changes in local trace pattern variations around the vicinity of bump and the test mimics the forces experienced by the bump during flip-chip assembly reflow process. Through this experimental and theoretical modeling research, guidelines are also developed for the reliable design of BEOL stacks for current and next-generation microelectronic devices.
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Islam, Mohammad Majharul. "Global-local Finite Element Fracture Analysis of Curvilinearly Stiffened Panels and Adhesive Joints." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/38687.
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Global-local finite element analyses were used to study the damage tolerance of curvilinearly stiffened panels; fabricated using the modern additive manufacturing process, the so-called unitized structures, and that of adhesive joints. A damage tolerance study of the unitized structures requires cracks to be defined in the vicinity of the critical stress zone. With the damage tolerance study of unitized structures as the focus, responses of curvilinearly stiffened panels to the combined shear and compression loadings were studied for different stiffenersâ height. It was observed that the magnitude of the minimum principal stress in the panel was larger than the magnitudes of the maximum principal and von Mises stresses. It was also observed that the critical buckling load factor increased significantly with the increase of stiffenersâ height.
To study the damage tolerance of curvilinearly stiffened panels, in the first step, buckling analysis of panels was performed to determine whether panels satisfied the buckling constraint. In the second step, stress distributions of the panel were analyzed to determine the location of the critical stress under the combined shear and compression loadings. Then, the fracture analysis of the curvilinearly stiffened panel with a crack of size 1.45 mm defined at the location of the critical stress, which was the common location with the maximum magnitude of the principal stresses and von Mises stress, was performed under combined shear and tensile loadings. This crack size was used because of the requirement of a sufficiently small crack, if the crack is in the vicinity of any stress raiser. A mesh sensitivity analysis was performed to validate the choice of the mesh density near the crack tip. All analyses were performed using global-local finite element method using MSC. Marc, and global finite element methods using MSC. Marc and ABAQUS. Negligible difference in results and 94% saving in the CPU time was achieved using the global-local finite element method over the global finite element method by using a mesh density of 8.4 element/mm ahead of the crack tip. To study the influence of different loads on basic modes of fracture, the shear and normal (tensile) loads were varied differently. It was observed that the case with the fixed shear load but variable normal loads and the case with the fixed normal load but variable shear loads were Mode-I. Under the maximum combined loading condition, the largest effective stress intensity factor was very smaller than the critical stress intensity factor. Therefore, considering the critical stress intensity factor of the panel with the crack of size 1.45 mm, the design of the stiffened panel was an optimum design satisfying damage tolerance constraints.
To acquire the trends in stress intensity factors for different crack lengths under different loadings, fracture analyses of curvilinearly stiffened panels with different crack lengths were performed by using a global-local finite element method under three different load cases: a) a shear load, b) a normal load, and c) a combined shear and normal loads. It was observed that 85% data storage space and the same amount in CPU time requirement could be saved using global-local finite element method compared to the standard global finite element analysis. It was also observed that the fracture mode in panels with different crack lengths was essentially Mode-I under the normal load case; Mode-II under the shear load case; and again Mode-I under the combined load case. Under the combined loading condition, the largest effective stress intensity factor of the panel with a crack of recommended size, if the crack is not in the vicinity of any stress raiser, was very smaller than the critical stress intensity factor.
This work also includes the performance evaluation of adhesive joints of two different materials. This research was motivated by our experience of an adhesive joint failure on a test-fixture that we used to experimentally validate the design of stiffened panels under a compression-shear load. In the test-fixture, steel tabs were adhesively bonded to an aluminum panel and this adhesive joint debonded before design loads on the test panel were fully applied. Therefore, the requirement of studying behavior of adhesive joints for assembling dissimilar materials was found to be necessary. To determine the failure load responsible for debonding of adhesive joints of two dissimilar materials, stress distributions in adhesive joints of the nonlinear finite element model of the test-fixture were studied under a gradually increasing compression-shear load. Since the design of the combined load test fixture was for transferring the in-plane shear and compression loads to the panel, in-plane loads might have been responsible for the debonding of the steel tabs, which was similar to the results obtained from the nonlinear finite element analysis of the combined load test fixture.
Then, fundamental studies were performed on the three-dimensional finite element models of adhesive lap joints and the Asymmetric Double Cantilever Beam (ADCB) joints for shear and peel deformations subjected to a loading similar to the in-plane loading conditions in the test-fixtures. The analysis was performed using ABAQUS, and the cohesive zone modeling was used to study the debonding growth. It was observed that the stronger adhesive joints could be obtained using the tougher adhesive and thicker adherends. The effect of end constraints on the fracture resistance of the ADCB specimen under compression was also investigated. The numerical observations showed that the delamination for the fixed end ADCB joints was more gradual than for the free end ADCB joints.
Finally, both the crack propagation and the characteristics of adhesive joints were studied using a global-local finite element method. Three cases were studied using the proposed global-local finite element method: a) adhesively bonded Double Cantilever Beam (DCB), b) an adhesive lap joint, and c) a three-point bending test specimen. Using global-local methods, in a crack propagation problem of an adhesively bonded DCB, more than 80% data storage space and more than 65% CPU time requirement could be saved. In the adhesive lap joints, around 70% data storage space and 70% CPU time requirement could be saved using the global-local method. For the three-point bending test specimen case, more than 90% for both data storage space and CPU time requirement could be saved using the global-local method.Ph. D.
Book chapters on the topic "Cohesive zone law"
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Kovalchick, Christopher, Shuman Xia, and Guruswami Ravichandran. "Cohesive Zone Law Extraction from an Experimental Peel Test." In Conference Proceedings of the Society for Experimental Mechanics Series, 237–45. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-4226-4_28.
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Hong, Soonsung. "Identification of Cohesive-Zone Laws from Crack-tip Deformation Fields." In Application of Imaging Techniques to Mechanics of Materials and Structures, Volume 4, 7–9. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4419-9796-8_2.
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Gamstedt, E. K., T. K. Jacobsen, and B. F. Sørensen. "Determination of Cohesive Laws for Materials Exhibiting Large Scale Damage Zones." In IUTAM Symposium on Analytical and Computational Fracture Mechanics of Non-Homogeneous Materials, 349–53. Dordrecht: Springer Netherlands, 2002. http://dx.doi.org/10.1007/978-94-017-0081-8_38.
Full textConference papers on the topic "Cohesive zone law"
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Stigh, Ulf, K. Svante Alfredsson, and Anders Biel. "Measurement of Cohesive Laws and Related Problems." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-10474.
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Cohesive modelling provides a simple method to introduce a process region in models of fracture. It is computationally attractive since it blends into the structure of finite element programmes for stress analysis. The development of computational methods and applications of cohesive modelling has accelerated during recent years. Methods to measure cohesive laws have also been developed. One class of such methods is based on the path-independence of the J-integral. By choosing a path encircling the cohesive zone, J can be shown to be given by the area under the traction-separation relation for the cohesive zone. Using an alternative path, J can in some cases be directly related to the applied load and deformation with relatively modest or no assumptions on the material behaviour. Thus, the cohesive law can be measured. Methods to measure cohesive laws for different specimen geometries are presented. The methods are used to measure the cohesive law in peel, shear and mixed-mode for an adhesive layer. A new method to measure cohesive laws in shear is presented. The method is shown to give accurate data with a much smaller test specimen than earlier methods.
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Shishir, MD Imrul Reza, and Alireza Tabarraei. "Molecular Dynamics Simulation Based Cohesive Zone Representation of Intergranular Fracture Processes in Bicrystalline Graphene." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23624.
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Abstract The fracture properties of various grain boundaries in graphene are investigated using the cohesive zone method (CZM). Molecular dynamics simulations are conducted using REBO2+S potential in order to develop a cohesive zone model for graphene grain boundaries using a double cantilever bicrystalline graphene sheet. The cohesive zone model is used to investigate the traction–separation law to understand the separation-work and strength of grain boundaries.
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Dunbar, Andrew, Xin Wang, Bill (W R. ). Tyson, and Su Xu. "Simulation of Ductile Crack Propagation in Pipeline Steels Using Cohesive Zone Modeling." In ASME 2012 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/pvp2012-78091.
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This paper presents recent results of numerical studies on stable crack extension of high toughness steels typical of those in modern gas pipelines using cohesive zone modeling. Two sets of materials are modeled. The first material set models a typical structural steel, with variable toughness described by four traction-separation (TS) laws. The second set models an X70 pipe steel, with three different TS laws. For each TS law, there are three defining parameters: the maximum cohesive strength, the final separation and the work of separation. The specimens analyzed include a crack in an infinite plate (small-scale yielding, SSY) and a standard drop-weight tear test (DWTT). Fracture propagation characteristics and values of crack-tip opening angle (CTOA) are obtained from these two types of specimens. It is shown that cohesive zone models can be successfully used to simulate ductile crack propagation and to numerically measure CTOAs. The ductile crack propagation characteristics and CTOAs obtained from SSY and DWTT specimens are compared for each set of steels. In addition, the CTOA results from numerical cohesive zone modeling of DWTT specimens of X70 steel are compared with those from laboratory tests.
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Chaudhari, Vikas, D. M. Kulkarni, Shivam Rathi, Akshay Sancheti, and Swadesh Dixit. "Investigation of Cohesive Zone Model Parameters for Steel Used in Shipbuilding Structure." In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-70977.
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Present work deals with the investigation of fracture toughness and modeling parameters need in FEA application for steel use in shipbuilding structure. The investigated steel was 12.5mm thick low carbon high strength steel. Two types of tests were performed, tensile test and fracture test to evaluate mechanical properties and fracture toughness respectively. Cohesive zone model (CZM) was used because it is very computer effective and requires only two parameters, which can be determined in experiments with relative ease. Cohesive zone model with trapezoidal traction law found suitable for the investigated steel. To simulate CZM, bulk section with plane stress elements and bulk section with plane stress with plane strain core scheme are found suitable however bulk section with plane stress with plane strain core scheme gives accurate numerical results.
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Simatos, A., S. Marie, A. Combescure, and F. Cazes. "Modelling Ductile Tearing From Diffuse Plasticity to Crack Propagation." In ASME 2010 Pressure Vessels and Piping Division/K-PVP Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/pvp2010-25387.
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Continuum models for ductile fracture accurately model onset of ductile tearing thanks to their stress triaxiality dependent formulations. Nevertheless, these models are subject to localization and convergence problems that hinder large crack propagation prediction. This paper presents a method to switch from a continuum mechanics model to a cohesive zone maintaining the mechanical energy. This is obtained thanks to a careful identification of the cohesive law whose computation is based on two points: The thermodynamical definition of the cohesive model and the assumption that, for a given problem, the plastic work during localization must be the same if modelled with a regularized continuum model or with introduction of an equivalent cohesive zone. The cohesive discontinuity is introduced in the framework of the eXtended Finite Element Method developed in CAST3M Finite Element code. This strategy permits to use the continuum model as long as it is the most appropriate and to introduce cohesive zone segments without energy loss. Moreover it solves numerical difficulties associated with the local vision of fracture. The performance of the proposed solution is illustrated on the Rousselier model for which a consistent cohesive law is identified. Results of fracture tests prediction on a CT specimen are compared with those obtained with the conventional Rousselier continuum mechanics formulation.
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Truong, Do Van. "Simulation of Crack Initiation at the Interface Edge Between Sub-Micron Thick Films Under Creep by Cohesive Zone Model." In ASME 2008 International Manufacturing Science and Engineering Conference collocated with the 3rd JSME/ASME International Conference on Materials and Processing. ASMEDC, 2008. http://dx.doi.org/10.1115/msec_icmp2008-72061.
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Delamination between sub-micron thick films is initiated at an interface edge due to creep deformation, and leads to the malfunction of microelectronic devices. In this study, the cohesive zone model approach with a cohesive law based on damage mechanics was developed to simulate crack initiation process at an interface edge between film layers under creep. Delamination experiments using a micro-cantilever bend specimen with a Sn/Si interface were conducted. The parameters charactering the cohesive law were calibrated by fitting displacement-time curves obtained by experiments and simulations. In addition, the order of the stress singularity, which increases with time and has a significant jump in its value at the crack initiation, was investigated.
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Ji, Gefu, Zhenyu Ouyang, Guoqiang Li, H. Dwayne Jerro, and Su-Seng Pang. "Effect of Bondline Thickness on Interfacial Fracture of Laminated Composite Materials." In ASME 2010 Pressure Vessels and Piping Division/K-PVP Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/pvp2010-25714.
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The interfacial fracture of bonded structures is a critical issue for the extensive applications to a variety of modern industries. In the recent two decades, nonlinear fracture mechanics methods have been receiving intensive attentions for adhesively bonded joints. Extensive experimental efforts have been made to determine the toughness of adhesive joints. Several experimental studies have also been conducted to determine the interface cohesive law in bonded joints. However, very few studies investigated the effect of adhesive thickness on the interface cohesive laws. In the cohesive law, both fracture energy and the interfacial cohesive strength, as two critical parameters, have significant effect on the fracture behavior and joint’s structural capability. The present study presents the experimental investigation into how the adhesive’s thickness affect these two important parameters with the nonlinear fracture mechanics. The equivalent interface cohesive laws are experimentally determined for the bonded joints with various adhesive thicknesses. The experimental cohesive laws may provide valuable baseline data for simple analytical and numerical cohesive zone models. Based on the test results, the mechanism for the intrinsic fracture energy and plastic energy dissipation is discussed. Several other interesting conclusions are also obtained.
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Ji, Gefu, Zhenyu Ouyang, Guoqiang Li, Su-Seng Pang, and Samuel Ibekwe. "Effect of Adhesive Thickness on Interfacial Fracture of Bonded Steel Joints." In ASME 2010 Pressure Vessels and Piping Division/K-PVP Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/pvp2010-25755.
Full textAbstract:
The interfacial fracture of bonded structures is a critical issue for the extensive applications to a variety of modern industries. In the recent two decades, nonlinear fracture mechanics methods have been receiving intensive attentions for adhesively bonded joints. Extensive experimental efforts have been made to determine the toughness of adhesive joints. Several experimental studies have also been conducted to determine the interface cohesive law in bonded joints. However, very few studies investigated the effect of adhesive thickness on the interface cohesive laws. In the cohesive law, both fracture energy and the interfacial cohesive strength, as two critical parameters, have significant effect on the fracture behavior and joint’s structural capability. The present study presents the experimental investigation into how the adhesive’s thickness affect these two important parameters with the nonlinear fracture mechanics. At the mean time, the equivalent interface cohesive laws are experimentally determined for the bonded joints with various adhesive thicknesses. The experimental cohesive laws may provide valuable baseline data for simple analytical and numerical cohesive zone models. With the test results, the mechanism for the intrinsic fracture energy and plastic energy dissipation is discussed. Several other interesting conclusions are also obtained.
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Wang, Yanfei, Jianming Gong, Luyang Geng, and Yong Jiang. "Prediction on Initiation of Hydrogen-Induced Delayed Cracking in High-Strength Steel Based on Cohesive Zone Modeling." In ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28964.
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This study presents prediction on initiation of hydrogen-induced delayed cracking (HIDC) in hydrogen pre-charged high-strength steel notched bars under a constant load based on hydrogen influenced cohesive zone modeling (CZM). The prediction is implemented by using a three-step sequential coupling finite element procedure including elastic-plastic stress analysis, stress-assisted hydrogen diffusion analysis and cohesive stress analysis with cohesive elements embedded along the potential crack path. Hydrogen influenced linear traction separation law is applied to the cohesive elements. The predicted initiation time of HIDC gives a good agreement with the experimental fracture time reported in a literature. The prediction reproduces the experimental trend that the critical hydrogen concentration for crack initiation is independent of the initial hydrogen concentration, while decreases with increasing load or stress concentration factor of the notch. CZM has a potential to predict HIDC of high-strength steel.
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Parmar, Shreya, Xin Wang, Bill (W R. ). Tyson, and Su Xu. "Simulation of Ductile Fracture in Pipeline Steels Under Varying Constraint Conditions Using Cohesive Zone Modeling." In ASME 2015 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/pvp2015-45873.
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Fracture propagation toughness is important to pipeline steels. In this study, the effect of non-singular T-stress (a measure of constraint) on crack growth resistance curves (R-curves) and crack tip opening angle (CTOA) was investigated using modified boundary layer (MBL) models of pipeline steels. Two sets of steel types: 1) TH (a typical high strength steel) and 2) C4 (X100 steel) were used in this work. Surface-based cohesive zone models with four sets of bilinear traction-separation (TS) laws were used for TH steel. The models of C4 steel were computed using element-based cohesive zone modeling with one bilinear TS law. All finite element simulations were conducted using the finite element (FE) program ABAQUS. It was assumed in these simulations that there was no effect of T-stress on the TS laws per se. With this assumption, it was found that the T-stress does not have a significant effect on the CTOA for the two materials studied.