Artykuły w czasopismach: „VCCT”

1

Zhou, Li Ming, Guang Wei Meng, Feng Li i Hui Wang. "Cell-Based Smoothed Finite Element Method-Virtual Crack Closure Technique for a Piezoelectric Material of Crack". Mathematical Problems in Engineering 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/371083.

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In order to improve the accuracy and efficiency of solving fracture parameters of piezoelectric materials, a piezoelectric element, tailored for the virtual crack closure technique (VCCT), was used to study piezoelectric materials containing a crack. Recently, the cell-based smoothed finite element method (CSFEM) and VCCT have been used to simulate the fracture mechanics of piezoelectric materials. A center cracked piezoelectric materials with different material properties, crack length, mesh, and smoothing subcells at various strain energy release rates are discussed and compared with finite element method-virtual crack closure technique (FEM-VCCT). Numerical examples show that CSFEM-VCCT gives an improved simulation compared to FEM-VCCT, which generally simulates materials as too stiff with lower accuracy and efficiency. Due to its simplicity, the VCCT piezoelectric element demonstrated in this study could be a potential tool for engineers to practice piezoelectric fracture analysis. CSFEM-VCCT is an efficient numerical method for fracture analysis of piezoelectric materials.

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Liu, Bing, Jie Meng, Zhen Yang, Ying Wang, Hua Zhi Xie, Wen Chao Zhang, Cheng Ming He i Xiang Yang Deng. "Exploration of the Relationship of the Voltage Critical Clearing Time and the Voltage Transient Transmission Capacity". Applied Mechanics and Materials 488-489 (styczeń 2014): 905–9. http://dx.doi.org/10.4028/www.scientific.net/amm.488-489.905.

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Both the voltage critical clearing time (VCCT) and the voltage transient transmission capacity (VTTC) are always used to evaluate the stability of the system transient voltage, and their relationships are studied and clarified in the paper. The stability of the transient voltage is mainly depended on the dynamic reactive characteristics of load and the transmission characteristics of voltage and power. Based on the analysis on the dynamic reactive characteristics of load and the transmission characteristics of a power transmission network, the characteristics of the VCCT and the VTTC are studied in this paper. Finally, a conclusion, i.e. the margin of the VCCT and the VTTC has a nonlinear characteristic, is obtained by simulations on the actual power grid. According to the conclusion, the voltage stability cannot be exactly reflected by the VCCT margin.

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3

Krscanski, Sanjin, i Josip Brnic. "Prediction of Fatigue Crack Growth in Metallic Specimens under Constant Amplitude Loading Using Virtual Crack Closure and Forman Model". Metals 10, nr 7 (20.07.2020): 977. http://dx.doi.org/10.3390/met10070977.

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This paper considers the applicability of virtual crack closure technique (VCCT) for calculation of stress intensity factor range for crack propagation in standard metal specimen geometries with sharp through thickness cracks. To determine crack propagation rate and fatigue lifetime of a dynamically loaded metallic specimen, in addition to VCCT, standard Forman model was used. Values of stress intensity factor (SIF) ranges ΔK for various crack lengths were calculated by VCCT and used in conjunction with material parameters available from several research papers. VCCT was chosen as a method of choice for the calculation of stress intensity factor of a crack as it is simple and relatively straightforward to implement. It is relatively easy for implementation on top of any finite element (FE) code and it does not require the use of any special finite elements. It is usually utilized for fracture analysis of brittle materials when plastic dissipation is negligible, i.e., plastic dissipation belongs to small-scale yielding due to low load on a structural element. Obtained results showed that the application of VCCT yields good results. Results for crack propagation rate and total lifetime for three test cases were compared to available experimental data and showed satisfactory correlation.

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4

Miravete, Antonio, i Miguel A. Jime´nez. "Application of the finite element method to prediction of onset of delamination growth". Applied Mechanics Reviews 55, nr 2 (1.03.2002): 89–106. http://dx.doi.org/10.1115/1.1450763.

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The present article is concerned with the application of the finite element method to the analysis of the onset of delamination growth in composites by means of the virtual crack closure technique (VCCT). The article reviews first the application of linear elastic fracture mechanics (LEFM) to the analysis of delamination, as well as the reasons why the VCC technique is the standard method of combining LEFM and the finite element method to predict onset of delamination growth. The article also reviews the different solutions proposed in the literature to deal with the oscillatory singularity associated with a crack between two dissimilar materials (as is the case for a delamination) and the practical details of the VCCT application in a general 3D analysis. Finally, the results of a numerical study of the mixed mode bending (MMB) interlaminar fracture test are shown. The study applies the concepts reviewed along the rest of this article and presents some practical recommendations for the analysis of a delamination front using finite elements. This review article includes 77 references.

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5

Zhou, Li Ming, Guang Wei Meng, Xiao Lin Li i Feng Li. "Analysis of Dynamic Fracture Parameters in Functionally Graded Material Plates with Cracks by Graded Finite Element Method and Virtual Crack Closure Technique". Advances in Materials Science and Engineering 2016 (2016): 1–14. http://dx.doi.org/10.1155/2016/8085107.

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Based on the finite element software ABAQUS and graded element method, we developed a dummy node fracture element, wrote the user subroutines UMAT and UEL, and solved the energy release rate component of functionally graded material (FGM) plates with cracks. An interface element tailored for the virtual crack closure technique (VCCT) was applied. Fixed cracks and moving cracks under dynamic loads were simulated. The results were compared to other VCCT-based analyses. With the implementation of a crack speed function within the element, it can be easily expanded to the cases of varying crack velocities, without convergence difficulty for all cases. Neither singular element nor collapsed element was required. Therefore, due to its simplicity, the VCCT interface element is a potential tool for engineers to conduct dynamic fracture analysis in conjunction with commercial finite element analysis codes.

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Wang, Changsong. "Asymmetries in two types ofde-related verb-copying constructionsin Mandarin Chinese". International Journal of Chinese Linguistics 8, nr 2 (31.12.2021): 241–90. http://dx.doi.org/10.1075/ijchl.20007.wan.

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Abstract This article studies Chinese V-de sentences from the perspective of verb-copying constructions (VCC) and presents some more evidence in favor of the distinction between descriptive V-de constructions and resultative V-de constructions. VCC with descriptive V-de sentences (VCCD) and VCC with resultative V-de sentences (VCCR) are linearly described as [NP1+ V1+ NP2 + V2 + de +XP]. Five asymmetries, though not very sharp, have been observed between VCCD and VCCR: (a) the movement asymmetry of [V1+NP2], (b) the questioning asymmetry between weishenme ‘why’ and shenme ‘what’, (c) the definiteness asymmetry of NP2, (d) the repetition asymmetry of V1, and (e) the asymmetry of subject-oriented adverb guyi ‘intentionally’. To explain these differences, we assume that [V1+NP2] in VCCD is a constituent, acting as an internal topic. While similar analysis cannot be extended to VCCR. We propose instead that [NP1+V1+NP2] is a constituent in VCCR, projecting further into a complex NP and acting as a sentential subject. These structural differences can well explain the five asymmetries from the island effects, and the semantic and pragmatic constraints (on internal topics and subject-oriented adverbs). Meanwhile, based on the restriction of manner adverbial modification, the V2 in VCCD and VCCR is assumed to be externally merged at the morphological level via External Morphological Merger to satisfy the affixal properties of de. The copying of V1 as V2 is not driven syntactically, but morphologically. This morphosyntactic approach to VCCD and VCCR provides a new perspective to explore V-de sentences and VCC, which may shed light on the morphosyntactic studies of Mandarin Chinese from a crosslinguistic perspective.

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Zhou, Hong Liang. "Implementation of Crack Problem of Functionally Graded Materials with ABAQUS^TM". Advanced Materials Research 284-286 (lipiec 2011): 297–300. http://dx.doi.org/10.4028/www.scientific.net/amr.284-286.297.

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An implementation method of the virtual crack closure technique (VCCT) for fracture problems of non-homogeneous materials such as functionally graded materials (FGMs) with commercial finite element software ABAQUSTMis introduced in this paper. In order to avoid the complex post proceeding to extract fracture parameters, the interface crack element based on the VCCT is developed. The heterogeneity of FGMs is characterized though user subroutine UMAT and the interface crack element is implemented by user subroutine UEL. Several examples are analyzed to demonstrate the accuracy of the present method.

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Xi, Liang, Xiu Li Zhao, Chong Wei Shang, Guang Ming Kong i Xu Liu. "Fatigue Crack Propagation Life Prediction of 2A12 Aluminum Alloy Based on VCCT". Advanced Materials Research 1081 (grudzień 2014): 196–99. http://dx.doi.org/10.4028/www.scientific.net/amr.1081.196.

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The fatigue crack propagation behavior of the prior corrosion 2A12 aluminum alloy fastener involving a central hole was investigated. The virtual crack closure technique (VCCT), is straightforward and not sensitive to the FEA mesh size, was carried out to calculate strain energy release rate and SIFs of AA 2A12 under different stress levels and corrosion years. Based on the VCCT, the simulation carried out to analyze the corrosion fatigue crack growth behavior. It was proved to be convenient to simulate the crack propagation life and the predicted crack growth curve was in good agreement with the experimental results.

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9

Zhong, Zhi Peng, Shui Wan i Lin Yun Zhou. "A new Interface Element Method on Computation of the Interface Crack Propagation Energy Release Rate". Applied Mechanics and Materials 204-208 (październik 2012): 4573–77. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.4573.

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A new interface element method was proposed to calculate the strain energy release rates(SERR) based on the virtual crack closure technique (VCCT). A Lagrange multiplier was introduced between the node pair at crack tip to obtain the internal forces. Then from the VCCT, the SERR was solved by using the forces and displacements near the crack tip. Examples for stationary cracks under the two typical cases are given. Meanwhile, the relationship curves between crack energy release rate and the length of crack, plate depths were plotted respectively.The example shows that the interface element used to calculate the SERR is simple, efficient, and highly accurate in analysis of 2D crack growth problems, and without requiring the special singularity element or collapsed element at crack tip.

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Kocur-Bera, Katarzyna, i Szymon Czyża. "Socio-Economic Vulnerability to Climate Change in Rural Areas in the Context of Green Energy Development—A Study of the Great Masurian Lakes Mesoregion". International Journal of Environmental Research and Public Health 20, nr 3 (2.02.2023): 2689. http://dx.doi.org/10.3390/ijerph20032689.

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Green energy production has become a common and recognized method of electricity generation. Giving up reliance on non-renewable energy sources is an important trend in the economies of many countries. The paper presents an analysis of the impact of indicators like increased green energy production on the level of vulnerability to climate change. The model of the Climate Change Vulnerability Index (VCC) recommended by the Intergovernmental Panel on Climate Change (considering three aspects: exposure, vulnerability, and adaptive capacity of the studied spatial unit/society) was applied. Sensitivity analysis, spatial heterogeneity, and temporal dynamics of indicators characterizing changes in electricity consumption, renewable energy production, greenhouse gas emissions, and variability of financial losses due to extreme weather events and their number were implemented. Several findings arose. First, the vulnerability to climate change (the level of the VCC index), does not decrease after the implementation of a single action, like the development of green energy production. The level of index of vulnerability to climate change (VCC1) from the reference year (2017) relative to VCC2 (2021) has changed slightly, despite the development of RES. The variation does not exceed a 1% reduction in the value of the VCC1 index. Second, the decrease in the level of the vulnerability requires global, coordinated action. The value of the VCC3 index, reflecting, including changes in green energy production (X15), electricity consumption/inhabitant (X38), and green-house gas emissions (X14), exhibited more favorably the impact of these indicators on vulnerability to climate change, compared to the VCC1 reference value. In eleven poviats, the VCC3 index decreased between 1 and 4%. In seven of these poviats, green energy production increased, resulting in an average 10% decrease in the X15 indicator, the X14 indicator representing green-house gas emissions decreased by an average of 7%, while the X38 indicator describing electricity consumption/per capita decreased by an average of 16%. Third, harmonized and inclusive action by the population holds the potential to be the clue to reducing vulnerability to climate change

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Gliszczynski, A., S. Samborski, N. Wiacek i J. Rzeczkowski. "Mode I Interlaminar Fracture of Glass/Epoxy Unidirectional Laminates. Part II: Numerical Analysis". Materials 12, nr 10 (16.05.2019): 1604. http://dx.doi.org/10.3390/ma12101604.

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The paper deals with numerical analysis of double cantilever beam (DCB) predefined to Mode I Interlaminar Fracture Tests of GRFP unidirectional laminates. The numerical analyses were performed in the ANSYS® program based on the finite element. In geometrically nonlinear analysis, two algorithms, responsible for initiation and propagation of delamination front, were applied: Virtual Crack Closure Technique (VCCT) and Cohesive zone method (CZM). Due to the unidirectional arrangement of layers of the laminate, the problem of DCB test was solved with the use of one- and three-dimensional models with the implementation of linear interface element and contact element. The present study highlights the limitations of existing formulae used to reliably reflect the behavior of DCB. The use of three-dimensional models allowed confirming the curved shape of the delamination front observed in experimental studies. The application of the VCCT in the three-dimensional model led to an underestimation of the global response (force–opening displacement curve) recorded during numerical DCB test.

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Hasani Najafabadi, S. H., Stefano Zucca, D. S. Paolino, G. Chiandussi i Massimo Rossetto. "Numerical Computation of Stress Intensity Factors in Ultrasonic Very-High-Cycle Fatigue Tests". Key Engineering Materials 754 (wrzesień 2017): 218–21. http://dx.doi.org/10.4028/www.scientific.net/kem.754.218.

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The correct computation of the Stress Intensity Factor (SIF) in ultrasonic Very-High-Cycle Fatigue (VHCF) loading conditions is a key issue when investigating the crack growth rate curve with pre-cracked specimens or when evaluating critical SIF values from fracture surfaces of failed specimens. Dynamic conditions related to the resonance of the vibrating specimen, contact nonlinearity between crack faces and stress singularity at the crack tip make the SIF computation difficult and cumbersome. Generally, numerical computation through Finite Element Models (FEMs) under non-linear dynamic conditions makes use of direct integration methods (implicit or explicit). However, in the high frequency regime of ultrasonic VHCF tests, the procedure may lead to an unacceptable computational time. In order to reduce the computational time, a hybrid procedure based on the Harmonic Balance Method (HBM) and on the Virtual Crack Closure Technique (VCCT) is originally presented and applied in this paper. The dynamic field parameters calculated with the HBM are used as input data for the computation of the SIF through the VCCT.

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Wu, Mengjie, Yuyan Zhang, Xin Dai i Ling Jiang. "Studies on the Mechanical Models and Behaviors for the Stamp/Film Interface in Microtransfer Printing". Materials 15, nr 17 (26.08.2022): 5915. http://dx.doi.org/10.3390/ma15175915.

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The adhesion/delamination characteristics at the stamp/film interface are critical for the efficiency of film microtransfer printing technology. To predict and regulate the interface mechanical behaviors, finite element models based on the J-integral, Virtual Crack Closure Technology (VCCT), and the cohesive zone method (CZM) were established and compared. Then, the effects of pulling speed and interface parameters on the pull-off force, which is used to characterize the interface adhesion strength, were investigated. Comparisons between the simulation results and previous experimental results demonstrated that the model based on the CZM was more applicable than the models based on the J-integral and VCCT in analyzing the adhesion/delamination behaviors of the stamp/film interface. Furthermore, the increase in pulling speed could enlarge the pull-off force for the viscoelastic stamp/film interface, while it had no influence on the pull-off force for the elastic stamp/film interface. In addition, a larger normal strength and normal fracture energy resulted in a larger pull-off force, which was beneficial to the realization of the picking-up process in microtransfer printing.

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Bacarreza, Omar, i M. H. Aliabadi. "A Novel Methodology for Fatigue Delamination Growth Analysis of Composites". Key Engineering Materials 488-489 (wrzesień 2011): 763–66. http://dx.doi.org/10.4028/www.scientific.net/kem.488-489.763.

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A novel methodology for analysis of fatigue delamination growth, capable of dealing with complex delamination shapes and mixed-modes in a computationally efficient way, is proposed. It combines the VCCT to find the energy release rates and the XFEM to update the geometry during the progressive failure, thus making it very robust and computationally efficient. The methodology is demonstrated at coupon level.

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Pirondi, A., G. Giuliese i F. Moroni. "Development of a cohesive zone model for three-dimensional simulation of joint de-bonding/delamination under mixed-mode I/II fatigue loading". International Journal of Structural Integrity 5, nr 3 (12.08.2014): 171–86. http://dx.doi.org/10.1108/ijsi-02-2014-0008.

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Purpose – In this work, the cohesive zone model (CZM) developed by some of the authors to simulate the propagation of fatigue defects in two dimensions is extended in order to simulate the propagation of defects in 3D. The paper aims to discuss this issue. Design/methodology/approach – The procedure has been implemented in the finite element (FE) solver (Abaqus) by programming the appropriate software-embedded subroutines. Part of the procedure is devoted to the calculation of the rate of energy release per unit, G, necessary to know the growth of the defect. Findings – The model was tested on different joint geometries, with different load conditions (pure mode I, mode II pure, mixed mode I/II) and the results of the analysis were compared with analytical solutions or virtual crack closure technique (VCCT). Originality/value – The possibility to simulate the growth of a crack without any re-meshing requirements and the relatively easy possibility to manipulate the constitutive law of the cohesive elements makes the CZM attractive also for the fatigue crack growth simulation. However, differently from VCCT, three-dimensional fatigue de-bonding/delamination with CZM is not yet state-of-art in FE softwares.

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Rzeczkowski, Jakub, i Sylwester Samborski. "Experimental and Numerical Research of Delamination Process in CFRP Laminates with Bending-Twisting Elastic Couplings". Materials 15, nr 21 (3.11.2022): 7745. http://dx.doi.org/10.3390/ma15217745.

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This paper aims at experimental and numerical research of delamination process in carbon/epoxy composite laminates with different fiber orientation angles in stacking sequence exhibiting the bending–twisting elastic couplings. Experimental specimens were subjected to the double cantilever beam (DCB) tests according to the ASTM D5528 regulations. Values of the mode I strain energy release rates were calculated by using three different data reduction schemes: the modified beam theory, the compliance calibration method and the modified compliance calibration. Determination of delamination initiation point was conducted in twofold way: by visual observation of crack tip using high resolution camera and by utilization of the acoustic emission technique. Numerical analyss were prepared in Abaqus/CAE Software environment by using the virtual crack closure technique (VCCT). The numerical beam model consisted of SC8R continuum shell elements. Obtained outcomes revealed that extensive fiber bridging phenomenon occurring during delamination process pronouncedly affected propagation values of strain energy release rate (GIprop) and numerically obtained load–displacement curves. Nevertheless, in initial stage of delamination, results obtained by using the VCCT were in agreement with experimental data. The greatest value of the mode I fracture toughness equal 0.56 N/mm was obtained for the BT45 laminate.

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Hao, Rui, Zongyi Wen, Haohui Xin i Weiwei Lin. "Fatigue Life Prediction of Notched Details Using SWT Model and LEFM-Based Approach". Materials 16, nr 5 (26.02.2023): 1942. http://dx.doi.org/10.3390/ma16051942.

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The fatigue crack initiation life of unwelded steel components accounts for the majority of the total fatigue life, and the accurate prediction of it is of vital importance. In this study, a numerical model utilizing the extended finite element method (XFEM) and Smith–Watson–Topper (SWT) model is established to predict the fatigue crack initiation life of notched details extensively used in orthotropic steel deck bridges. Using the user subroutine UDMGINI in Abaqus, a new algorithm was proposed to calculate the damage parameter of SWT under high-cycle fatigue loads. The virtual crack-closure technique (VCCT) was introduced to monitor crack propagation. Nineteen tests were performed, and the results were used to validate the proposed algorithm and XFEM model. The simulation results show that the proposed XFEM model with UDMGINI and VCCT can reasonably predict the fatigue lives of the notched specimens within the regime of high-cycle fatigue with a load ratio of 0.1. The error for the prediction of fatigue initiation life ranges from −27.5% to 41.1%, and the prediction of total fatigue life has a good agreement with the experimental results with a scatter factor of around 2.

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Kim, T. W., H. Y. Jeong, J. H. Choe i Y. H. Kim. "Prediction of the Fatigue Life of Tires Using CED and VCCT". Key Engineering Materials 297-300 (listopad 2005): 102–7. http://dx.doi.org/10.4028/www.scientific.net/kem.297-300.102.

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A new simulation methodology using the finite element method (FEM) was proposed to predict the fatigue life of tires. In the FEM simulation the cracking energy density (CED) was calculated, and the virtual crack closure technique (VCCT) was used to calculate the strain energy release rate (SERR) for a crack. First, a plane in an element on which CED had its maximum was determined, and a crack was created on the plane. Once a crack was introduced, another plane on which CED had its maximum was again determined, and the crack was further elongated along the plane. In addition, SERR was calculated for every crack increment by using VCCT, and it was represented as a function of the crack length. Then, the fatigue life of a tire was determined using Paris law. For Paris law, the initial crack length and the final crack length as well as the material constants should be known. In this paper, the initial crack length was set in a way that the fatigue life predicted by using Paris law became the same as the test data for a tire model (Tire A), and the final crack length was determined from the cross-section views of failed tires which showed cracks grown about halfway toward the carcass from the carcass turn-up edge. Finally, the fatigue life for another tire model (Tire B) was predicted by using Paris law, and the predicted fatigue life was compared with the test data.

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Schmidt, Jakob, Marcus Klingenhöfer, Jörg Kaufmann, Holger Cebulla i Lothar Kroll. "Characterization of the interlaminar fracture toughness of unidirectional thermoplastic composites". Technologies for Lightweight Structures (TLS) 5, nr 1 (24.03.2022): 77–85. http://dx.doi.org/10.21935/tls.v5i1.157.

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In this study, the critical energy release rate in mode I (G1c) for thermoplastic composites made of carbon fiber (CF) and glass fiber (GF) with a polyamide 6 (PA6) matrix is investigated. Double cantilever beam (DCB) was used as the specimen for the mode I test, and the ASTM D 5528-13 was chosen as standard. Moreover, different methodological approaches were applied by comparing different data reduction schemes from the ASTM D 5528-13 and further analytic approaches from the literature. In addition to the conducted experiments, a numerical model of the DCB test is developed and the virtual crack closure technique (VCCT) is performed on the numerical model to determine G1c for PA6-CF and PA6-GF. For the interlaminar fracture toughness G1c a value of 2.87 mJ/mm2 was determined for PA6-GF and a value of 2.16 mJ/mm2 for PA6-CF, which indicate that the use of PA6 as matrix in a composite structure leads to good resistance to damage. A comparison of the different methodological approaches showed a good agreement between the analytical approaches from the literature and the ASTM D 5528-13. In contrast, the values generated for G1c by the VCCT method were significantly higher than those of the other methods.

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Katajisto, Harri, Petri Kere i Mikko Lyly. "A model for fast delamination analysis of laminated composite structures". Rakenteiden Mekaniikka 53, nr 2 (30.03.2020): 67–84. http://dx.doi.org/10.23998/rm.82730.

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Delamination is one of the major failure mechanisms for composites and traditionally the simulation requires high expertise in fracture mechanics and dedicated knowledge of the Finite Element Analysis (FEA) tool. Yet, the simulation cycle times are high. Geometrically nonlinear analysis approach, which is based on the Reissner-Mindlin-Von K´arm´an type shell facet model, has been implemented into the Elmer FE solver. Altair ESAComp software runs the Elmer Solver in the background. A post-processing capability, which enables the prediction of the delamination onset from the FEA output, has been implemented into the AltairESAComp software. A Virtual Crack Closure Technique (VCCT) speciﬁcally developed for shell elements deﬁning the Strain Energy Release Rate (SERR) related to the diﬀerent delamination modes at the crack front is used. The onset of delamination is predicted using the relevant delamination criteria that utilize the SERR data and material allowables in the form of fracture toughness. The modeling methodology is presented for laminates including initial through-the-width delamination. Examples include delamination in the solid laminate and debonding of the skin laminate in the sandwich structure. Rather coarse FE mesh has proved to yield good results when compared to typical approaches that utilize the standard VCCT or Cohesive Zone Elements.

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Wang, Qing Yuan, Yong Jie Liu, Xiang Guo Zeng i Hua Yan Chen. "Study on Calculation Method of Fracture Parameters of the Tubular Based on 3D VCCT". Key Engineering Materials 385-387 (lipiec 2008): 713–16. http://dx.doi.org/10.4028/www.scientific.net/kem.385-387.713.

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The stress intensity factor (SIF) for tubular specimens were calculated based on virtual crack closure technique （VCCT）. The effects of geomet rical factors (inner radius, wall thickness and relative crack length) and external loads on the SIF were analyzed, respectively, by use of the single-variable approach. Finally, an approximate formula for SIF of compact-tensile tubular specimens was obtained as all factors mentioned were considered, which was presented as a reference for the tubular engineering design.

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Vishwanath, K. S. "Computational Investigation of Square Embedded Delamination of a Composite Laminate using VCCT". International Journal for Research in Applied Science and Engineering Technology 9, nr VI (10.06.2021): 381–84. http://dx.doi.org/10.22214/ijraset.2021.34923.

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The fiber reinforced polymer laminates are widely implemented in aviation industry due to its advantages and applications other materials in terms of strength to weight ratio, dsign features and many more. The strength of the interface compared to longitudinal and lateral directions of the plies are comparatively less and give rise too poor transverse direction strength. Hence a failure mechanism called delamination will occur in case when tools are dropped or due to poor manufacturing which would give rise to interface delamination. In this paper, VCCT is employed at the interface between base and sub laminate to investigate for a square shape delamination geometry of 20mm buckling driven delamination growth. The computational prediction of delamination growth initiation is obtained by solving a T300/976 specimen for geometric non linearity using SC8R continuum shell elements of Abaqus CAE and by plotting the required energy release rate at the delamination geometry.

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Yao, Anlin, Wenbo He, Taolong Xu, Hongye Jiang i Dongfang Gu. "3D-VCCT based fracture analysis method for gas pipelines with multiple cracks". Natural Gas Industry B 6, nr 5 (październik 2019): 488–96. http://dx.doi.org/10.1016/j.ngib.2019.03.005.

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Karmakov, S., F. Cepero-Mejías i J. L. Curiel-Sosa. "Numerical analysis of the delamination in CFRP laminates: VCCT and XFEM assessment". Composites Part C: Open Access 2 (październik 2020): 100014. http://dx.doi.org/10.1016/j.jcomc.2020.100014.

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Tawfik, Ahmed Bahgat, Sameh Youssef Mahfouz i Salah El-Din Fahmy Taher. "Nonlinear ABAQUS Simulations for Notched Concrete Beams". Materials 14, nr 23 (30.11.2021): 7349. http://dx.doi.org/10.3390/ma14237349.

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The numerical simulation of concrete fracture is difficult because of the brittle, inelastic-nonlinear nature of concrete. In this study, notched plain and reinforced concrete beams were investigated numerically to study their flexural response using different crack simulation techniques in ABAQUS. The flexural response was expressed by hardening and softening regime, flexural capacity, failure ductility, damage initiation and propagation, fracture energy, crack path, and crack mouth opening displacement. The employed techniques were the contour integral technique (CIT), the extended finite element method (XFEM), and the virtual crack closure technique (VCCT). A parametric study regarding the initial notch-to-depth ratio (ao/D), the shear span-to-depth ratio (S.S/D), and external post-tensioning (EPT) were investigated. It was found that both XFEM and VCCT produced better results, but XFEM had better flexural simulation. Contrarily, the CIT models failed to express the softening behavior and to capture the crack path. Furthermore, the flexural capacity was increased after reducing the (ao/D) and after decreasing the S.S/D. Additionally, using EPT increased the flexural capacity, showed the ductile flexural response, and reduced the flexural softening. Moreover, using reinforcement led to more ductile behavior, controlled damage propagation, and a dramatic increase in the flexural capacity. Furthermore, CIT showed reliable results for reinforced concrete beams, unlike plain concrete beams.

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Vishwanath, K. S. "Computational Investigation of through the Width Delamination of a Composite Laminate using VCCT". International Journal for Research in Applied Science and Engineering Technology 9, nr VI (10.06.2021): 128–31. http://dx.doi.org/10.22214/ijraset.2021.34890.

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The fiber reinforced polymer laminates have found extensive applications because of its advantages over other materials in terms of strength, stiffness, stability, weight saving features, resistance to corrosion and erosion and many more. But due to poor transverse direction strength, a failure mechanism called delamination will occur in case of poor manufacturing or when tools are dropped which would make an impact. In this paper, VCCT is implemented at the interface between base and sub laminate to investigate for 20mm through the width buckling driven delamination growth. The computational prediction of delamination growth initiation is obtained by solving a T300/976 specimen for geometric non linearity using SC8R continuum shell elements of Abaqus CAE and by plotting the required energy release rate at the edge of delamination geometry.

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Wang, Dong Xu, i Liang Wu. "Virtual Crack Closure Technique in the Analysis of Concrete Arch Dam Cracks". Applied Mechanics and Materials 444-445 (październik 2013): 1466–70. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.1466.

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In this paper, a 3-dimension finite element with dummy nodes for calculating and outputting the stress energy release (SERR) at the crack tip was built up based on virtual crack closure technique (VCCT), it is presented to demonstrate the virtual crack closure technique has high accuracy and good feasibility. The calculation results curve and the analytical solution curve are in good agreement. The results show that the proposed interface elements can be used to calculate to get accurate results by finite element analysis. It can give us some new ideas for Hydraulic structure crack research.

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Kong, Guang Ming, Xu Dong Li i Zhi Tao Mu. "Corrosion Fatigue Crack Propagation of 6151-T6 Aluminum Alloy Based on Virtual Crack Closure Technique". Advanced Materials Research 998-999 (lipiec 2014): 31–34. http://dx.doi.org/10.4028/www.scientific.net/amr.998-999.31.

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Using the virtual crack closure technique (VCCT), an interface element that can calculate stress intensity factors (SIFs) directly and simulate the crack propagation conveniently has been developed. Based on an accelerated corrosion experiment, the fatigue crack propagation behavior of the 6151-T6 aluminum alloys under different corrosion years and stress levels were simulated, and it was proved to be convenient to calculate strain energy release rate and SIFs of AA 6151-T6 under different stress levels and corrosion years. The proposed method is characterized by higher accuracy and less calculation elements, provides a new way for engineering fracture analysis of the structure.

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Ahn, Jae S., i Kwang S. Woo. "Delamination of laminated composite plates by p-convergent partial discrete-layer elements with VCCT". Mechanics Research Communications 66 (czerwiec 2015): 60–69. http://dx.doi.org/10.1016/j.mechrescom.2015.02.009.

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Liu, Yong Jie, Qing Yuan Wang, Xiang Guo Zeng i Da Li Lv. "Numerical Analysis of Fracture Parameters of Multiple Interacting Cracks". Key Engineering Materials 417-418 (październik 2009): 277–80. http://dx.doi.org/10.4028/www.scientific.net/kem.417-418.277.

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Multiple interacting crack problems for 3-point bending specimen were studied in this article. Two symmetrical minor cracks were placed in the structure, besides a main crack at the middle, and using the finite element method program ABAQUS, the energy release rate (G) and the stress intensity factor (SIF) were evaluated based on the virtual crack closure technology（VCCT）in conjunction with finite element analysis(FEA). Then, effects of variation in relative lengths and locations of the minor cracks on the stress intensity factors of the main crack were obtained and analyzed. Finally, the approach was applied to dynamic analysis, and influences of interacting effects among the cracks on dynamic fracture parameters were also studied.

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31

Soltani, Hamid, S. M. Mohseni Shakib, M. Asadi i M. K. Ramezani. "Computational Investigation of Delamination in HAT-Section Laminated Composite Components". Applied Mechanics and Materials 110-116 (październik 2011): 1161–65. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.1161.

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This paper aims at developing the numerical of delamination in laminated composite structures. Formation of initial delamination and growth of existing delamination in HAT-Section laminated made of plies of unidirectional carbon fiber reinforced epoxy resin is investigated computationally. Tsai-Hill failure method is employed to predict delamination initiation while delamination propagation is analyzed using linear elastic fracture mechanics (LEFM).The techniques based on LEFM that have been utilized successfully within the framework of the finite element method (FEM) for the simulation of delamination growth, the virtual crack closer technique (VCCT). Finally this paper proposes future work for precise prediction of delamination of unidirectional carbon fiber reinforced epoxy resin HAT-Section specimens.

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32

Cui, Wei, Zhongmin Xiao, Jie Yang, Mi Tian, Qiang Zhang i Ziming Feng. "Multi-Crack Dynamic Interaction Effect on Oil and Gas Pipeline Weld Joints Based on VCCT". Energies 15, nr 8 (12.04.2022): 2812. http://dx.doi.org/10.3390/en15082812.

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In pipelines for transporting oil and gas, multiple cracks often exist in weld joints. The interaction among the cracks should be considered as it directly affects the life span of the pipeline structures. In the current investigation, based on the fluid–solid magnetic coupling model, the virtual crack-closure technique (VCCT) is applied to systematically study the multi-crack dynamic interaction effect on pipeline welds during the crack propagation process. The results show that the existence of an auxiliary crack accelerates the main crack’s propagation. When the auxiliary crack is nearer to the main crack tip, the enhancement effect of the auxiliary crack on the main crack increases. Further, when the initial length of the auxiliary crack increases, the main crack becomes easier to propagate. Two important parameters, the distance between the two interacting crack tips and the initial size of the auxiliary crack, are studied in detail. Their interference effect on the main crack has been quantified, which is very user-friendly for engineers to conduct failure assessment and prevention for oil and gas pipes with multiple cracks at weld joints.

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33

Vishwanath, K. S. "FEA of Circular Embedded Delamination with Variations in Temperature in a Composite Laminate using VCCT". International Journal for Research in Applied Science and Engineering Technology 9, nr VI (30.06.2021): 5058–61. http://dx.doi.org/10.22214/ijraset.2021.36122.

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The FRP laminates are widely implemented in aviation industry due to its advantages and applications other materials in terms of strength to weight ratio, design features and many more. The strength of the interface compared to longitudinal and lateral directions of the plies are comparatively less and give rise too poor transverse direction strength. Hence a failure mechanism called delamination will occur in case when tools are dropped or due to poor manufacturing which would give rise to interface delamination. In this paper, VCCT is employed at the interface between base and sub laminate to investigate for a circular shape delamination geometry of 60mm buckling driven delamination growth with variations in temperature for -20C, room temperature, 523C, 773C and 1273C. The computational prediction of delamination growth initiation is obtained by solving a CFRP specimen for geometric non linearity using SC8R continuum shell elements of Abaqus CAE and by plotting the required energy release rate versus inplane strains and inplane loads versus compressive strains.

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Busari, Yusuf O., Yupiter H. P. Manurung, Martin Leitner, Yusuf L. Shuaib-Babata, Muhd F. Mat, Hassan K. Ibrahim, David Simunek i Mohd Shahar Sulaiman. "Numerical Evaluation of Fatigue Crack Growth of Structural Steels Using Energy Release Rate with VCCT". Applied Sciences 12, nr 5 (3.03.2022): 2641. http://dx.doi.org/10.3390/app12052641.

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This research presents the numerical evaluation of fatigue crack growth of structural steels S355 and S960 based on Paris’ law parameters (C and m) that are experimentally determined with a single edge notched tension (SENT) specimen using optical and crack gauge measurements on an electromotive resonance machine at constant amplitude load. The sustainable technique is replacing destructive, time-consuming and expensive approaches in structural integrity. The crack propagation is modelled using the 3D finite element method (FEM) with adaptive remeshing of tetrahedral elements along with the crack initiator elements provided in simulation software for crack propagation based on linear elastic fracture mechanics (LEFM). The stress intensity is computed based on the evaluation of energy release rates according to Irwin’s crack closure integral with applied cyclic load of 62.5 MPa, 100 MPa and 150 MPa and stress ratios of R = 0 and 0.1. In order to achieve optimized mesh size towards load cycle and computational time, mesh and re-mesh sensitivity analysis is conducted. The results indicate that the virtual crack closure technique VCCT-based 3D FEM shows acceptable agreement compared to the experimental investigation with the percentage error up to 7.9% for S355 and 12.8% for S960 structural steel.

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35

Wilk, Jakub. "NUMERICAL MODELING OF FATIGUE DELAMINATION GROWTH IN LAMINATES UNDER MODEL I LOADING CONDITIONS USING VCCT". Transactions of the Institute of Aviation 245, nr 4 (30.12.2016): 227–38. http://dx.doi.org/10.5604/05096669.1226897.

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Jokinen, J., i M. Kanerva. "Simulation of Delamination Growth at CFRP-Tungsten Aerospace Laminates Using VCCT and CZM Modelling Techniques". Applied Composite Materials 26, nr 3 (20.11.2018): 709–21. http://dx.doi.org/10.1007/s10443-018-9746-5.

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Jokinen, Jarno, Markus Wallin i Olli Saarela. "Applicability of VCCT in mode I loading of yielding adhesively bonded joints—a case study". International Journal of Adhesion and Adhesives 62 (październik 2015): 85–91. http://dx.doi.org/10.1016/j.ijadhadh.2015.07.004.

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Ma, Yu E., Bao Qi Liu i Zhen Qiang Zhao. "Damage Tolerance Properties of 2198-T8 Integral Fuselage Panel between Double Friction Stir Weld Joints". Applied Mechanics and Materials 138-139 (listopad 2011): 651–56. http://dx.doi.org/10.4028/www.scientific.net/amm.138-139.651.

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Al-Li alloy 2198-T8 was used in the fuselage application. Integral fuselage panels were joined by double friction stir welds. Fatigue tests were conducted in the R=0.1. Notch was made between two welds. Residual stresses were measured and analyzed in the test samples with double welds. Cracks grew from the centre of two welds and across the two welds were observed, and crack growth rates were measured and compared with parent material. It is shown that crack growth rates are lower between double welds, and it is close to parent material after cross the two welds. The virtual crack closure technique (VCCT) method was used to calculate stress intensity factor from residual stress (Kres) in aim to explain the experimental findings.

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39

Sun, Zhi Jia, You Tang Li i Hong Yan Duan. "Consistent Mode Mixity for the Interface Crack of the Bimaterial Disc under Diametric Compression Loading". Applied Mechanics and Materials 345 (sierpień 2013): 268–71. http://dx.doi.org/10.4028/www.scientific.net/amm.345.268.

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The bimaterial disc specimen with central interface crack under diametric compression loading was simulated using the finite element method (FEM). The mode mixity for the interface crack was controlled by varying the compression angle. The consistent mode mixity independent of the assumed crack-extension size was obtained using the virtual crack closure technique (VCCT) by introducing an arbitrary normalizing length lG.The relations of the compression angle and the oscillation index ε to the consistent mode mixity were discussed with the simulation results. It found that the critical compression angles corresponding to pure mode ΙΙ got closed to 250 as the absolute value of ε was very small and a fitted formula of the critical compression angle and the absolute value of ε was also obtained.

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40

Shokrieh, M. M., H. Rajabpour-Shirazi, M. Heidari-Rarani i M. Haghpanahi. "Simulation of mode I delamination propagation in multidirectional composites with R-curve effects using VCCT method". Computational Materials Science 65 (grudzień 2012): 66–73. http://dx.doi.org/10.1016/j.commatsci.2012.06.025.

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41

Ahn, Jae Seok, Kwang Sung Woo i Dong Woo Lee. "Delamination Analysis of Carbon Fiber-Reinforced PEEK Using Coarse Mesh". Advanced Materials Research 538-541 (czerwiec 2012): 1624–29. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.1624.

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The simulation of the delamination process in composite structures made from carbon fiber-reinforced polyetheretherketone (PEEK) is quite complex and requires advanced finite element modeling techniques. Failure analysis tools must be able to predict initiation, size and propagation of delamination process. The objective of the paper is to present modeling technique which is able to predict a delamination in a double-cantilever-beam (DCB) test. The approach is to use a fracture mechanics criterion, but to avoid the complex moving mesh technique. The modeling technique using coarse mesh adopts higher-order approximation (p-level=8) based on Lobatto shape functions. For fracture analysis, also, virtual crack closure technique (VCCT) is considered. Using moving nodal modes, the delamination analysis is implemented and then the performance of present analysis is demonstrated by comparing with the results of references.

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42

El Moufari, Meryem, i Larbi El Bakkali. "Fracture Toughness Analysis of Delamineted Composites under Variable Temperatures". Mechanics and Mechanical Engineering 22, nr 1 (12.08.2020): 171–78. http://dx.doi.org/10.2478/mme-2018-0015.

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AbstractThe main goal of the present paper is to approach the modeling of one of the most important and critical failure modes for composite laminates which is known as interlaminar delamination in the aeronautical structures. The analytical model is based on a fracture mechanics approach; it’s used to estimate the total mixed mode energy release rate for composite laminates. A finite element simulation has been achieved in combination with the virtual crack closure technique (VCCT) to analyze the effect of temperature on the interlaminar fracture toughness growth of a delaminated carbon/epoxy material, namely IM7/8552 subjected to mechanical loading at variable temperatures. The developed model may serve as the basis for treating different types of thermal and mechanical loading, different stacking sequences and thickness of lamina in order to build safe working conditions for composite laminates.

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Steurer, Michael Morten, Ulrike Aust i Ludwig Huber. "The Vienna comparative cognition technology (VCCT): An innovative operant conditioning system for various species and experimental procedures". Behavior Research Methods 44, nr 4 (22.03.2012): 909–18. http://dx.doi.org/10.3758/s13428-012-0198-9.

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Jeevan Kumar, N. "Analysis of Mode-I crack growth arresting mechanism in curved laminated joint". International Journal of Computational Materials Science and Engineering 08, nr 01 (marzec 2019): 1950001. http://dx.doi.org/10.1142/s2047684119500015.

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The critical damage for carbon fiber structures, which are being employed in aircraft structures, is known as delamination/crack. Fasteners are commonly installed to arrest the delamination by clamping the laminate together. Fasteners are installed in each corner of the delaminated zone to provide significant arrest capability, shifting the failure mode away from delamination under most conditions. The Finite Element Analysis (FEA) model is constructed to study the effectiveness of the fastener as crack arrest mechanism. The FEA results show that the fastener provides significant crack retardation capability in Mode-I condition. An analytical model is developed for the delamination embedded between the skin and stiffener interface of the joint. The fasteners are modeled with spring elements. The analysis is solved with Virtual Crack Closure Technique (VCCT) approach. The primary objective of the current research work is to enhance the safety of bonded joint by providing arrest mechanisms.

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Teimouri, Farhad, Mohammad Heidari-Rarani i Farhad Haji Aboutalebi. "An XFEM-VCCT coupled approach for modeling mode I fatigue delamination in composite laminates under high cycle loading". Engineering Fracture Mechanics 249 (maj 2021): 107760. http://dx.doi.org/10.1016/j.engfracmech.2021.107760.

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Liu, Yan-Ping, i Tian-Jun Li. "Application of the virtual crack closure technique (VCCT) using tetrahedral finite elements to calculate the stress intensity factor". Engineering Fracture Mechanics 253 (sierpień 2021): 107853. http://dx.doi.org/10.1016/j.engfracmech.2021.107853.

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Khatir, S., A. Behtani, S. Tiachacht, A. Bouazouni, M. Abdel Wahab i Y.-L. Zhou. "Delamination detection in laminated composite using Virtual crack closure technique (VCCT) and modal flexibility based on dynamic analysis". Journal of Physics: Conference Series 842 (maj 2017): 012084. http://dx.doi.org/10.1088/1742-6596/842/1/012084.

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Wang, Zhenqing, Fang Liu, Wenyan Liang i Limin Zhou. "Study on Tensile Properties of Nanoreinforced Epoxy Polymer: Macroscopic Experiments and Nanoscale FEM Simulation Prediction". Advances in Materials Science and Engineering 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/392450.

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The effect of nanosilica contents on mechanical properties of the epoxy matrix with some nanoparticle aggregations was studied in macroscopic experiments and nanoscale simulation, particularly with regard to the effective modulus and ultimate stress. Three analytical models were used to obtain the effective elastic modulus of nanoparticle-reinforced composites. Based on Monte-Carlo method, the special program for the automatic generation of 2D random distribution particles without overlapping was developed for nanocomposite modeling. Weight fractions of nanoparticles were converted to volume fractions, in order to coordinate the content unit in the simulation. In numerical analysis, the weak interface strengthening and toughening mechanism was adopted. Virtual crack closure technique (VCCT) and extended finite element method (XFEM) were used to simulate phenomena of nanoparticle debonding and matrix crack growth. Experimental and simulation results show a good agreement with each other. By way of simulation, the weak interface toughening and strengthening mechanism of nanocomposites is confirmed.

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Sellitto, Andrea, Aniello Riccio, A. Russo, Antonio Garofano i Mauro Zarrelli. "Nanofillers’ Effects on Fracture Energy in Composite Aerospace Structures". Key Engineering Materials 827 (grudzień 2019): 43–48. http://dx.doi.org/10.4028/www.scientific.net/kem.827.43.

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Composite materials damage behaviour is, nowadays, extensively investigated in the frame of aerospace research programmes. Among the several failure mechanisms which can affect composites, delamination can be considered as the most critical one, especially when combined to compressive loading conditions. In this context, nanofillers can represent an effective way to increase the composites fracture toughness with a consequent reduction of the delamination onset and evolution. Hence, in this paper, the toughening effect of the nanofillers on the delamination growth in composite material panels, subject to compressive load, has been numerically studied. A validated robust numerical procedure for the prediction of the delamination growth in composite materials panel, named SMXB and based on the VCCT-Fail release approach, has been used to perform numerical analyses by considering two different types of nanofillers. Reference material, without nanofillers insertion, has been used as benchmark in order to assess the capability of nanofillers to enhance the fracture toughness in composite laminates.

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KRUSE, Charli, Dagmar K. WILLKOMM, Arnold GRÜNWELLER, Tillmann VOLLBRANDT, Stefanie SOMMER, Silke BUSCH, Thomas PFEIFFER, Jürgen BRINKMANN, Roland K. HARTMANN i Peter K. MÜLLER. "Export and transport of tRNA are coupled to a multi-protein complex". Biochemical Journal 346, nr 1 (8.02.2000): 107–15. http://dx.doi.org/10.1042/bj3460107.

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Vigilin is a ubiquitous multi heterogeneous nuclear ribonucleoprotein (hnRNP) K homologous (KH)-domain protein. Here we demonstrate that purified recombinant human vigilin binds tRNA molecules with high affinity, although with limited specificity. Nuclear microinjection experiments revealed for the first time that the immuno-affinity-purified nuclear vigilin core complex (VCCN) as well as recombinant vigilin accelerate tRNA export from the nucleus in human cells. The nuclear tRNA receptor exportin-t is part of the VCCN. Elongation factor (EF)-1α is enriched in VCCN and its cytoplasmic counterpart VCCC, whereas EF-1β, EF-1γ and EF-1∆ are basically confined to the VCCC. Our results suggest further that vigilin and exportin-t might interact during tRNA export, provide evidence that the channeled tRNA cycle is already initiated in the nucleus, and illustrate that intracellular tRNA trafficking is associated with discrete changes in the composition of cellular cytoplasmic multi-protein complexes containing tRNA.

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