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A B De Morais - One of the best experts on this subject based on the ideXlab platform.

  • Determination of the shear traction-separation law of adhesive layers using the end-notched flexure specimen
    Engineering Fracture Mechanics, 2020
    Co-Authors: A B De Morais
    Abstract:

    Abstract Cohesive zone modelling is increasingly applied to predict the strength of structural adhesive joints. A method is here proposed to determine the bondline shear traction-separation law needed for cohesive zone models. The method combines an Effective Crack Length approach derived from a beam model and an existing J-integral analysis of the end-notched flexure specimen. The resulting work done by the tractions versus separation curves can be easily processed with direct or mixed direct-inverse approaches. Application to some published experimental results demonstrates the potential of the method while highlighting the importance of adherend material and specimen geometry selection.

  • Evaluation of a trilinear traction-separation law for mode II delamination using the Effective Crack method
    Composites Part A: Applied Science and Manufacturing, 2019
    Co-Authors: A B De Morais
    Abstract:

    Abstract Mode II delamination testing for measuring the critical strain-energy release rate has reached a high level of maturity with the recent publication of ISO and ASTM standards. Cohesive zone modelling has also become a well-established design tool implemented in many commercial finite element analysis codes. The particularly large fracture process zone in mode II delamination increases the relevance of the traction-separation law. This paper proposes a fairly simple inverse method to evaluate an approximate trilinear traction-separation law from quasi-static end-notched flexure test results. The method employs an analytical beam cohesive zone model and consists of evaluating the parameters that fit the Effective Crack Length versus strain-energy release rate curve. Preliminary studies showed that specific features of the latter curve were quite sensitive to some model parameters. Therefore, accurate approximate trilinear traction-separation laws could be obtained without the extensive numerical calculations typical of inverse methods.

  • Analysis of the fracture process zone and Effective Crack Length in the adhesively bonded end-notched flexure specimen
    'Informa UK Limited', 2019
    Co-Authors: A B De Morais
    Abstract:

    The mode II fracture of adhesive joints is well-known to involve large fracture process zones. Their effect in fracture energy measurements can be taken into account by the Effective Crack Length approach. Moreover, fracture process zones can be simulated by cohesive zone models, which are increasingly used for structural analysis of adhesive joints. This paper aimed at evaluating the influence of the traction-separation law on the fracture process zone and on the Effective Crack Length in end-notched flexure tests. Novel analytical cohesive zone models were developed for the bilinear and trapezoidal traction-separation laws. The latter were shown to affect significantly the energy dissipation rate versus Effective Crack Length curve prior to Crack initiation. Therefore, this effect seems to provide a simple approach for evaluating approximate traction-separation laws. The models here developed are easy to apply and provide simple approximate expressions useful for specimen selection.publishe

  • Evaluation of a trilinear traction-separation law for mode II delamination using the Effective Crack method
    'Elsevier BV', 2019
    Co-Authors: A B De Morais
    Abstract:

    Mode II delamination testing for measuring the critical strain-energy release rate has reached a high level of maturity with the recent publication of ISO and ASTM standards. Cohesive zone modelling has also become a well-established design tool implemented in many commercial finite element analysis codes. The particularly large fracture process zone in mode II delamination increases the relevance of the traction-separation law. This paper proposes a fairly simple inverse method to evaluate an approximate trilinear traction-separation law from quasi-static end-notched flexure test results. The method employs an analytical beam cohesive zone model and consists of evaluating the parameters that fit the Effective Crack Length versus strain-energy release rate curve. Preliminary studies showed that specific features of the latter curve were quite sensitive to some model parameters. Therefore, accurate approximate trilinear traction-separation laws could be obtained without the extensive numerical calculations typical of inverse methods.publishe

  • Analysis of the fracture process zone and Effective Crack Length in the adhesively bonded end-notched flexure specimen
    The Journal of Adhesion, 2018
    Co-Authors: A B De Morais
    Abstract:

    ABSTRACTThe mode II fracture of adhesive joints is well-known to involve large fracture process zones. Their effect in fracture energy measurements can be taken into account by the Effective Crack Length approach. Moreover, fracture process zones can be simulated by cohesive zone models, which are increasingly used for structural analysis of adhesive joints. This paper aimed at evaluating the influence of the traction-separation law on the fracture process zone and on the Effective Crack Length in end-notched flexure tests. Novel analytical cohesive zone models were developed for the bilinear and trapezoidal traction-separation laws. The latter were shown to affect significantly the energy dissipation rate versus Effective Crack Length curve prior to Crack initiation. Therefore, this effect seems to provide a simple approach for evaluating approximate traction-separation laws. The models here developed are easy to apply and provide simple approximate expressions useful for specimen selection.

Julien Jumel - One of the best experts on this subject based on the ideXlab platform.

  • Inverse End Loaded Split test configuration for stable mode II Crack propagation in bonded joint: macroscopic analysis—Effective Crack Length approach
    International Journal of Fracture, 2017
    Co-Authors: Michal K. Budzik, Julien Jumel
    Abstract:

    Mode II Crack propagation along a bonded joint is investigated using newly proposed Inverse-End Loaded Split experimental configurations. This test configuration allows stable Crack propagation all along the Crack propagation path. The specimen compliance and strain energy release rate for the new experimental arrangement are derived. An experimental data reduction procedure, based on the Effective Crack Length approach, is also proposed. Two series of experiments are performed to assess the stable nature of the Crack propagation and data reduction scheme associated to this new experimental arrangement. In addition to stable Crack growth, the experiment may prove his worthiness in the study of Crack onset under mode II loading.

  • Crack propagation along interface having randomly fluctuating mechanical properties during DCB test finite difference implementation – Evaluation of Gc distribution with Effective Crack Length technique
    Composites Part B: Engineering, 2017
    Co-Authors: Julien Jumel
    Abstract:

    Abstract A finite difference numerical scheme is implemented to study the Crack initiation and propagation along a Double Cantilever Beam specimen assuming either elastic-brittle interface or elastic perfectly plastic behavior. The finite difference calculations are first compared to known analytic solution to evidence the benefits and limits of this numerical method. Then randomly fluctuating interface properties along the Crack propagation path is considered to investigate the effect of variability on the force versus opening displacement evolution measured at a macroscopic scale. The local fluctuation of the critical Strain Energy Release Rate (SERR), Gc, could be estimated using the Effective Crack Length technique. However, local minima of the critical strain energy release rate induce unstable Crack propagation so that the weakest regions of the interface are not probed. Also, fluctuation of interface properties induce distortion of Gc distribution which could lead to non-conservative evaluation of the interface toughness.

P Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Prefabricated Crack Length on Fracture Toughness and Fracture Energy of Fly Ash Concrete Reinforced by Nano-SiO2 and Fibers
    Iranian Journal of Science and Technology Transactions of Civil Engineering, 2016
    Co-Authors: P Zhang, J. X. Gao, H. T. Zhu, M. Huang
    Abstract:

    This paper summarizes the test data obtained from an experimental investigation of nanoparticles and steel fiber-reinforced concrete. Tests were conducted to investigate the effect of prefabricated Crack Length on determining fracture parameters of concrete composite. The results reveal that most of the fracture parameters and the fracture relational curves of the concrete composite are influenced greatly by the prefabricated Crack Length of beam specimens, while the prefabricated Crack Length has little effect on the critical Crack tip opening displacement. There is a tendency for Effective Crack Length and the critical Crack mouth opening displacement to increase with the increase in prefabricated Crack Length, while the initial fracture toughness, unstable fracture toughness and fracture energy gradually decrease. Besides, when the prefabricated Crack Length decreases from 50 to 20 mm, these relational curves become much larger, and the nonlinear stage of the curves become longer and longer, and the descent stage of the curves become flatter and flatter.

  • Fracture properties of high performance concrete containing silica fume
    Australian Journal of Structural Engineering, 2013
    Co-Authors: P Zhang
    Abstract:

    A parametric experimental study has been conducted to investigate the effect of silica fume on the fracture properties of high performance concrete (HPC), with five silica fume contents (1.5%, 3%, 6%, 9% and 12%) used. The results indicate that the addition of silica fume has greatly improved the fracture parameters of HPC, such as fracture toughness, fracture energy, Effective Crack Length, the maximum mid-span deflection, the critical Crack opening displacement and the maximum Crack opening displacement of concrete. The fracture parameters of HPC containing silica fume are increasing gradually with the increase of silica fume content when the silica fume content increases from 0% to 3%, while, the fracture parameters begin to decrease after the silica fume content increases beyond 3%. However, the values of the fracture parameters of HPC with the silica fume content below 12% are still higher than that of the concrete without silica fume. It seems a small content of silica fume has an advantage of improvement of the fracture properties of HPC, while an overlarge silica fume content may adversely affect the fracture properties of HPC.

  • Effect of silica fume on fracture properties of high-performance concrete containing fly ash
    Proceedings of the Institution of Mechanical Engineers Part L: Journal of Materials: Design and Applications, 2012
    Co-Authors: P Zhang
    Abstract:

    A parametric experimental study has been conducted to investigate the effect of silica fume on the fracture properties of high-performance concrete containing fly ash, with four silica fume contents (3%, 6%, 9% and 12%) used. By means of three-point bending method, the fracture toughness, fracture energy, Effective Crack Length, critical Crack opening displacement and maximum Crack opening displacement of the specimen were measured, respectively. The results indicate that silica fume has great adverse effect on the fracture toughness, fracture energy, Effective Crack Length, critical Crack opening displacement and maximum Crack opening displacement, and these fracture parameters decrease gradually when the content of silica fume increases from 3% to 12%. Besides, as the silica fume content increases from 3% to 12%, the relational curves between the vertical load and the mid-span deflection (PV–� ), Crack mouth opening displacement (PV–CMOD) and Crack tip opening displacement (PV–CTOD) are becoming thinner and thinner, which indicates that the capability of high-performance concrete containing fly ash to resist Crack propagation is becoming weaker and weaker. It seems that the content of silica fume of high-performance concrete containing fly ash should be controlled strictly, and the silica fume content should be as low as possible on condition that the other properties of high-performance concrete can meet practical requirements.

J.m. Chandra Kishen - One of the best experts on this subject based on the ideXlab platform.

  • Residual fatigue strength assessment of concrete considering tension softening behavior
    International Journal of Fatigue, 2007
    Co-Authors: Trisha Sain, J.m. Chandra Kishen
    Abstract:

    In this study, the residual strength of plain concrete beams under fatigue loading is assessed. The quasi-brittle nature of the material is considered by including the effect of tension-softening taking place in the fracture process zone. A two step approach is followed. In the first step, the Effective critical Crack Length for unstable fracture to occur is determined by using two different methods, namely a modified LEFM based fatigue Crack propagation law and the Crack resistance method. In the second step, the moment carrying capacity as a function of increasing Effective Crack Length is obtained in order to assess the residual strength of the member. A parametric study is performed by considering three different softening laws: linear, bilinear and power laws. It is seen that the bilinear softening law matches close to the experimental predictions of other investigators.

Zongcai Deng - One of the best experts on this subject based on the ideXlab platform.

  • The fracture and fatigue performance in flexure of carbon fiber reinforced concrete
    Cement and Concrete Composites, 2005
    Co-Authors: Zongcai Deng
    Abstract:

    Abstract The fracture parameters and fatigue performances of carbon fiber reinforced concrete is investigated by three point bending tests. In comparison with the results of quasi-static tests where no pre-cyclic loading is applied, the influence of pre-cyclic loading history on fracture parameters was researched by using compliance calibration. The test results show that the fracture parameters of carbon fiber reinforced concrete and plain concrete will be reduced if the pre-cyclic loading stress levels are higher than a certain threshold, and this threshold value for carbon fiber reinforced concrete is higher than that of plain concrete. The critical Effective Crack Length for carbon fiber reinforced concrete is significantly larger than that of plain concrete and independent of the pre-cyclic loading history and fatigue life. Carbon fiber reinforced concrete has a considerable beneficial effect on the behaviour of concrete subjected to flexure fatigue loading.