Papers by Keyword: Cohesive Zone Model (CZM)

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Authors: Jia Min Zhang, Bo Zhang, Jin Chang Wang
Abstract: Firstly, the parameters of cohesive zone model in ABAQUS software are calibrated through the cohesive constitutive model determined by cohesive potential energy, which is provided by Oriz and Pandofi(1999). Then, the validity and liability are verified by the single element example which compares extended finite element simulation with experimental results. Lastly, it puts forward the model of FEM based on the highway pre-sawed cracks. The curve of CMOD with changing temperature is obtained, and the curve can be divided into three stage segments. The middle stage segment changes dramatically for the local cracking in the crack tip field between asphalt surface and base. The research results illustrate the cracking mechanisms of asphalt pavement under changing temperature.
1721
Authors: Jin Chang Wang, Lei Zhang, Jia Min Zhang
Abstract: The research methods of Cohesive Zone Model (CZM) are introduced and the parameters of cohesive zone model in ABAQUS software are calibrated based on the cohesive constitutive model determined by the fracture energy. Besides adopting exponential cohesive zone model, this paper applies a bilinear one to simulate the crack propagation of a simply supported single-edge notched concrete beams SE(B) (Mode I) and make comparisons with experimental result. Finally, the results represent effectiveness of the effective modulus and the special advantage in term of failure of fracture based on the cohesive zone model, which is of directly guiding significance for achieving a deep going understanding of crack propagation.
1503
Authors: Vladislav Kozák, Ivo Dlouhý, Zdeněk Chlup
Abstract: The micromechanical modelling encounters a problem that is different from basic assumptions of continuum mechanics. The material is not uniform on the microscale level and the material within an element has its own complex microstructure. Therefore the concept of a representative volume element (RVE) has been introduced. The general advantage, compared to conventional fracture mechanics, is that, in principle, the parameters of the respective models depend only on the material and not on the geometry. These concepts guarantee transferability from specimen to components over a wide range of dimensions and geometries. The prediction of crack propagation through interface elements based on the fracture mechanics approach (damage) and cohesive zone model is presented. The cohesive model for crack propagation analysis is incorporated into finite element package by interface elements which separations are controlled by the traction-separation law.
145
Authors: Yan Qing Wu, Hui Ji Shi
Abstract: This study looks at the crack propagation characteristics based on the cohesive zone model (CZM), which is implemented as a user defined element within FE system ABAQUS. A planar crystal model is applied to the polycrystalline material at elevated temperature in which grain boundary regions are included. From the point of energy, interactions between the cohesive fracture process zones and matrix material are studied. It’s shown that the material parameter such as strain rate sensitivity of grain interior and grain boundary strongly influences the plastic and cohesive energy dissipation mechanisms. The higher the strain rate sensitivity is, the larger amount of the external work will be transformed into plastic dissipation energy than into cohesive energy which could delay the rupturing of cohesive zone. By comparisons, when strain rate sensitivity decreases, plastic dissipation energy is reduced and the cohesive dissipation energy increases. In this case, the cohesive zones fracture more quickly. In addition to the matrix material parameter, influence of cohesive strength and critical displacement in CZM on stress triaxiality at grain interior and grain boundary regions are also investigated. It’s shown that enhancing cohesive zones ductility could improve matrix materials resistance to void damage.
187
Authors: Marco Alfano, Franco Furgiuele, A. Leonardi, Carmine Maletta, Glaucio H. Paulino
Abstract: This paper deals with the application of Cohesive Zone Model (CZM) concepts to study mode I fracture in adhesive bonded joints. In particular, an intrinsic piece-wise linear cohesive surface relation is used in order to model fracture in a pre-cracked bonded Double Cantilever Beam (DCB) specimen. Finite element implementation of the CZM is accomplished by means of the user element (UEL) feature available in the FE commercial code ABAQUS. The sensitivity of the cohesive zone parameters (i.e. fracture strength and critical energy release rate) in predicting the overall mechanical response is first examined; subsequently, cohesive parameters are tuned comparing numerical simulations of the load-displacement curve with experimental results retrieved from literature.
13
Authors: Seung Yong Yang
Abstract: To explore the structural strength of CFRP shape memory alloy composites, it is necessary to evaluate the interface bonding strength. Jang and Kishi experimentally investigated the adhesive strength between NiTi fibers and CFRP composite [1]. In this paper, the interface de-decohesion behavior was simulated by three-dimensional cohesive zone method. The values of related numerical parameters were chosen to fit the experimental result.
196
Authors: Guo Bin Zhang, Huang Yuan
Abstract: Creep damage is an important failure factor of high-temperature alloy. The fatigue crack growth under elevated temperature of the material is investigated for life prediction. In this paper, the numerical simulation of the crack propagation in nickel-based super alloy, IN718, was presented. A modified creep damage model was employed to accumulate the creep damage under cyclic loading conditions. The numerical results exhibit a reasonable agreement in the comparison with the experimental data. The cohesive zone approach, combining with the extended finite element method, has the ability to simulate the creep-fatigue crack propagation even for more complex loading conditions and specimen geometries.
29
Authors: Jing Hui Liu
Abstract: Cracking in the surface layer of asphalt pavement has been shown to be a major source of distress in roadways. Asphalt mixture is typically a heterogeneous material composed of aggregates, binder and air voids. Previous cracking studies have not considered the material heterogeneity. Digital Image Processing techniques is a powerful tool to describe the microstructure of the material. A micromechanical cohesive zone model that introduces ductility at the crack tip has been used to simulate the cracking of asphalt mixtures. ABAQUS software is a convenient finite element method to conduct simulations of particular laboratory specimens such as Indirect Tensile Tests(IDT) considering the micromechanical model. Simulation results of the IDT compared favorably with experimental results. Even though this study presented a attempt of a numerical simulation of a simple IDT test, the theory and methods adopted by the study can be applied to the fatigue damage study under the complicated loading considering the material heterogeneity, and then would effectively allow researchers link the micro-scale damage observed on the local scale with the real pavements fail on the global scale.
477
Authors: N.M. Shaffiar, Z.B. Lai, Mohd Nasir Tamin
Abstract: The relatively brittle solder/IMC interface fracture process in reflowed solder joints is examined using finite element (FE) method. The interface decohesion is described using a traction-separation quadratic failure criterion along with a mixed-mode displacement formulation for the interface fracture event. Reflowed Sn-4Ag-0.5Cu (SAC405) solder ball on OSP copper pad and orthotropic FR4 substrate under ball shear push test condition at 3000 mm/sec is simulated. Unified inelastic strain constitutive model describes the strain rate-response of the SAC405 solder. Comparable simulated and measured load-displacement values during solder ball shear push test serve as validation of the damage-based FE model. Results indicate a nonlinear damage evolution at each material point of the solder/IMC interface during the ball shear push test. The normal-to-shear traction ratio at the onset of the interface fracture is 1.59 indicating significant induced bending effect due to shear tool clearance. Rapid interface crack propagation is predicted following crack initiation event with the average crack speed up to 24.6 times the applied shear tool speed. The high stress concentration along the edge of the solder/IMC interface facilitates local crack initiation and dictates the shape of the predicted dynamic crack front.
1409
Authors: Masamichi Kawai, Akihiro Tanaka
Abstract: Effects of the thickness of plies of the same orientation on the notched strength of symmetric cross-ply CFRP laminates are examined. Three kinds of symmetric cross-ply CFRP laminates with the same total number of plies and the different number and sequence of adjacent laminae of the same orientation are used. Notch sensitivity of those laminates is evaluated for different shapes of notches: double-edge notches (DEN) and a center open hole (CH). Validity of an analytical cohesive zone model (CZM) is evaluated by comparing with experimental results on the three kinds of cross-ply laminates with a center hole. It is clearly observed that the tensile fracture strengths of the DEN and CH specimens significantly reduce as the notch size increases. The sensitivity to notches is highest in the case of alternating cross-ply configuration. The results of this study suggest that additional energy dissipation due to damage around notches should appropriately be considered to estimate the effective fracture toughness used in CZM calculations, especially for a class of cross-ply laminates with lower notch sensitivity.
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