The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform

Fagen Li - One of the best experts on this subject based on the ideXlab platform.

  • determination of johnson cook parameters and evaluation of Charpy Impact Test performance for x80 pipeline steel
    International Journal of Mechanical Sciences, 2020
    Co-Authors: Ying Zhen, Ming Song, Haijiao Yi, Fagen Li, Xuyang Li
    Abstract:

    Abstract Controlling the Charpy Impact toughness of materials is the key to the ductile fracture arrest design of pipelines. The finite element method based on Johnson–Cook (J-C) model has become an effective method to assist the experimental study of material Impact toughness. In this paper, model parameters of J-C constitutive relation and damage parameters of J-C failure model for X80 pipeline steel have been determined experimentally from quasi-static uniaxial tension Tests and Split Hopkinson Pressure Bar (SHPB) Tests. Charpy Impact Test has been simulated using J-C constitutive and failure models with the determined parameters. Reasonable agreements between the simulation and experimental results have been achieved. On this basis, the effects of the pendulum velocity, specimen width and striker radius on Charpy Impact Test results are studied. The results show that pendulum velocity has negligible influence on Charpy Impact Test results; the maximum force and Impact absorbed energy both have a highly linear relationship to specimen width; Charpy Impact Test is sensitive to striker geometry, the results measured by 2 mm-striker are obviously smaller than those of 8 mm-striker. Based on the above researches, the Impact absorbed energy correlation model between sub-size specimens and standard full-size specimens, the Test results transformation rules of the two strikers are established. The methods and results presented in this paper will provide references for dynamic behavior study, Impact dynamic design, pipeline safety operation and risk assessment of high-grade pipeline steel.

  • Determination of Johnson–Cook parameters and evaluation of Charpy Impact Test performance for X80 pipeline steel
    International Journal of Mechanical Sciences, 2020
    Co-Authors: Zhen Ying, Fagen Li, Song Ming, Yi Haijiao, Li Xuyang
    Abstract:

    Abstract Controlling the Charpy Impact toughness of materials is the key to the ductile fracture arrest design of pipelines. The finite element method based on Johnson–Cook (J-C) model has become an effective method to assist the experimental study of material Impact toughness. In this paper, model parameters of J-C constitutive relation and damage parameters of J-C failure model for X80 pipeline steel have been determined experimentally from quasi-static uniaxial tension Tests and Split Hopkinson Pressure Bar (SHPB) Tests. Charpy Impact Test has been simulated using J-C constitutive and failure models with the determined parameters. Reasonable agreements between the simulation and experimental results have been achieved. On this basis, the effects of the pendulum velocity, specimen width and striker radius on Charpy Impact Test results are studied. The results show that pendulum velocity has negligible influence on Charpy Impact Test results; the maximum force and Impact absorbed energy both have a highly linear relationship to specimen width; Charpy Impact Test is sensitive to striker geometry, the results measured by 2 mm-striker are obviously smaller than those of 8 mm-striker. Based on the above researches, the Impact absorbed energy correlation model between sub-size specimens and standard full-size specimens, the Test results transformation rules of the two strikers are established. The methods and results presented in this paper will provide references for dynamic behavior study, Impact dynamic design, pipeline safety operation and risk assessment of high-grade pipeline steel.

Xuyang Li - One of the best experts on this subject based on the ideXlab platform.

  • determination of johnson cook parameters and evaluation of Charpy Impact Test performance for x80 pipeline steel
    International Journal of Mechanical Sciences, 2020
    Co-Authors: Ying Zhen, Ming Song, Haijiao Yi, Fagen Li, Xuyang Li
    Abstract:

    Abstract Controlling the Charpy Impact toughness of materials is the key to the ductile fracture arrest design of pipelines. The finite element method based on Johnson–Cook (J-C) model has become an effective method to assist the experimental study of material Impact toughness. In this paper, model parameters of J-C constitutive relation and damage parameters of J-C failure model for X80 pipeline steel have been determined experimentally from quasi-static uniaxial tension Tests and Split Hopkinson Pressure Bar (SHPB) Tests. Charpy Impact Test has been simulated using J-C constitutive and failure models with the determined parameters. Reasonable agreements between the simulation and experimental results have been achieved. On this basis, the effects of the pendulum velocity, specimen width and striker radius on Charpy Impact Test results are studied. The results show that pendulum velocity has negligible influence on Charpy Impact Test results; the maximum force and Impact absorbed energy both have a highly linear relationship to specimen width; Charpy Impact Test is sensitive to striker geometry, the results measured by 2 mm-striker are obviously smaller than those of 8 mm-striker. Based on the above researches, the Impact absorbed energy correlation model between sub-size specimens and standard full-size specimens, the Test results transformation rules of the two strikers are established. The methods and results presented in this paper will provide references for dynamic behavior study, Impact dynamic design, pipeline safety operation and risk assessment of high-grade pipeline steel.

Wolfgang Grellmann - One of the best experts on this subject based on the ideXlab platform.

  • Acoustic Emission Analysis for Assessment of Damage Kinetics of Short-Glass Fibre-Reinforced Thermoplastics—ESEM Investigations and Instrumented Charpy Impact Test
    Deformation and Fracture Behaviour of Polymer Materials, 2017
    Co-Authors: Marcus Schoßig, Christian Bierogel, Armin Zankel, Peter Polt, Wolfgang Grellmann
    Abstract:

    The acoustic emission (AE) analysis is a structure-sensitive Test method of plastic diagnostics, which enables the characterisation of the damage kinetics as well as damage mechanisms under specific conditions. The AE analysis is linked to release of stored elastic energy, which propagates as spherical volume wave in the material. In this work, short-glass fibre-reinforced thermoplastic materials were examined in the quasi-static tensile Test in the environmental scanning electron microscope (ESEM) with simultaneously recording of the AE as well as under Impact-loading conditions in the instrumented Charpy Impact Test (ICIT). Therefore, it was possible to couple the mechanical, the acoustic and the micromechanical results to describe the damage kinetic as well as the damage mechanisms. In dependence on the bonding conditions of the glass fibre in the polymer matrix, different mechanisms of damage to be related to typical frequency ranges can be detected: (i) fibre fracture, (ii) matrix deformation with slipping of fibres in the delamination area and friction processes of the fibres in the matrix, (iii) debonding and pull-out with/without matrix yielding. The coupling of the AE analysis with the ICIT allows the assessment of the damage kinetic and therefore, the determination of the damage initiation under Impact-loading conditions. However, in dependence on various bonding conditions, different results could be found. For good bonding conditions, the damage initiation takes placed before the material behaviour changes from elastic to elastic–plastic behaviour. This could be found for the short-glass fibre-reinforced high-density polyethylene materials. For the fibre-reinforced polybutene materials, the first AE takes place at the point of elastic–plastic material behaviour. An energetic approach of the damage initiation by the parameter J Si shows an independent behaviour from the polymer matrix as well as from the glass fibre content. For all investigated thermoplastics, a J Si-value of 0.8 N/mm as resistance against stable crack propagation could be determined.

  • a simple intrinsic measure for rapid crack propagation in bimodal polyethylene pipe grades validated by elastic plastic fracture mechanics analysis of data from instrumented Charpy Impact Test
    Polymer Engineering and Science, 2017
    Co-Authors: R Deblieck, D J M Van Beek, Mary Mccarthy, Petra Mindermann, Klaas Remerie, Beate Langer, Ralf Lach, Wolfgang Grellmann
    Abstract:

    Conventional Test procedures, such as the S4 Test to analyze the resistance against rapid crack propagation (RCP) of plastic pipe materials are characterized by usage of a lot of material, are far from saving of time and they are-in need of special experimental set-ups. Therefore, in the last decade, small-scale accelerated reliable Tests (SMART) are developed - worldwide to overcome the disadvantage of such conventional Tests. In this paper fracture mechanics based analysis of instrumented Charpy Impact Test data for a set of bimodal high-density polyethylene pipe grades are compared with data of the conventional Charpy Impact Test. From this comparison the Charpy Impact strength at −30°C comes forth as a robust reproducible measure of the resistance to RCP and it is therefore proposed as a SMART method to rank materials with respect to RCP resistance. POLYM. ENG. SCI., 2016. © 2016 Society of Plastics Engineers

  • acoustic emission analysis for assessment of damage kinetics of short glass fibre reinforced thermoplastics esem investigations and instrumented Charpy Impact Test
    Deformation and Fracture Behaviour of Polymer Materials, 2017
    Co-Authors: Marcus Schosig, Armin Zankel, Christian Bierogel, Peter Polt, Wolfgang Grellmann
    Abstract:

    The acoustic emission (AE) analysis is a structure-sensitive Test method of plastic diagnostics, which enables the characterisation of the damage kinetics as well as damage mechanisms under specific conditions. The AE analysis is linked to release of stored elastic energy, which propagates as spherical volume wave in the material. In this work, short-glass fibre-reinforced thermoplastic materials were examined in the quasi-static tensile Test in the environmental scanning electron microscope (ESEM) with simultaneously recording of the AE as well as under Impact-loading conditions in the instrumented Charpy Impact Test (ICIT). Therefore, it was possible to couple the mechanical, the acoustic and the micromechanical results to describe the damage kinetic as well as the damage mechanisms. In dependence on the bonding conditions of the glass fibre in the polymer matrix, different mechanisms of damage to be related to typical frequency ranges can be detected: (i) fibre fracture, (ii) matrix deformation with slipping of fibres in the delamination area and friction processes of the fibres in the matrix, (iii) debonding and pull-out with/without matrix yielding. The coupling of the AE analysis with the ICIT allows the assessment of the damage kinetic and therefore, the determination of the damage initiation under Impact-loading conditions. However, in dependence on various bonding conditions, different results could be found. For good bonding conditions, the damage initiation takes placed before the material behaviour changes from elastic to elastic–plastic behaviour. This could be found for the short-glass fibre-reinforced high-density polyethylene materials. For the fibre-reinforced polybutene materials, the first AE takes place at the point of elastic–plastic material behaviour. An energetic approach of the damage initiation by the parameter J Si shows an independent behaviour from the polymer matrix as well as from the glass fibre content. For all investigated thermoplastics, a J Si-value of 0.8 N/mm as resistance against stable crack propagation could be determined.

  • A simple intrinsic measure for rapid crack propagation in bimodal polyethylene pipe grades validated by elastic–plastic fracture mechanics analysis of data from instrumented Charpy Impact Test
    Polymer Engineering and Science, 2016
    Co-Authors: R Deblieck, D J M Van Beek, Mary Mccarthy, Petra Mindermann, Klaas Remerie, Beate Langer, Ralf Lach, Wolfgang Grellmann
    Abstract:

    Conventional Test procedures, such as the S4 Test to analyze the resistance against rapid crack propagation (RCP) of plastic pipe materials are characterized by usage of a lot of material, are far from saving of time and they are-in need of special experimental set-ups. Therefore, in the last decade, small-scale accelerated reliable Tests (SMART) are developed - worldwide to overcome the disadvantage of such conventional Tests. In this paper fracture mechanics based analysis of instrumented Charpy Impact Test data for a set of bimodal high-density polyethylene pipe grades are compared with data of the conventional Charpy Impact Test. From this comparison the Charpy Impact strength at −30°C comes forth as a robust reproducible measure of the resistance to RCP and it is therefore proposed as a SMART method to rank materials with respect to RCP resistance. POLYM. ENG. SCI., 2016. © 2016 Society of Plastics Engineers

Rahul Davis - One of the best experts on this subject based on the ideXlab platform.

  • an experimental study of the effect of thermal treatments Charpy Impact Test parameters on Impact toughness of en31 steel
    IOSR Journal of Mechanical and Civil Engineering, 2014
    Co-Authors: Khangamlung Kamei, Anna Garima William, L S Koveile, Noman Ahmad, Ananyo Chakravorty, Rahul Davis
    Abstract:

    Engineering materials, mostly steel and their alloys are heat treated to alter their mechanical and physical properties so as to meet the engineering applications. The objective of the research was to maximize the Impact toughness by selecting various combinations of Charpy Impact Test parameters, thermal treatments and their appropriate levels based on the three- level (L9) Orthogonal Arrays (OAs) with four factors to provide an efficient and effective method for determining the most significant factors and interactions in the given design problem. In this paper experiments were carried out to Study the Effect of Thermal Treatments (annealing, hardening, cryogenic treatment and tempering) on Impact Toughness. Heat treatments were performed at different temperature for annealing, hardening and tempering in an Electric furnace. Deep cryogenic treatment (DCT) was carried out on Cryocan at 77K. Various combinations of heat treatment cycles were performed to improve the mechanical properties of EN31 steel. This experimental also investigated the role of multiple cryogenic treatments before and after tempering. The findings show that Cryogenic treatment improves hardness, dimensional stability, and retained austenite to martensite and decreases residual stresses. This paper also studied and measured the hardness of various heat treated specimens using Brinell Hardness Tester.

  • An Experimental Study of the Effect of Thermal Treatments & Charpy Impact Test Parameters on Impact Toughness of EN31 Steel
    IOSR Journal of Mechanical and Civil Engineering, 2014
    Co-Authors: Khangamlung Kamei, Anna Garima William, L S Koveile, Noman Ahmad, Ananyo Chakravorty, Rahul Davis
    Abstract:

    Engineering materials, mostly steel and their alloys are heat treated to alter their mechanical and physical properties so as to meet the engineering applications. The objective of the research was to maximize the Impact toughness by selecting various combinations of Charpy Impact Test parameters, thermal treatments and their appropriate levels based on the three- level (L9) Orthogonal Arrays (OAs) with four factors to provide an efficient and effective method for determining the most significant factors and interactions in the given design problem. In this paper experiments were carried out to Study the Effect of Thermal Treatments (annealing, hardening, cryogenic treatment and tempering) on Impact Toughness. Heat treatments were performed at different temperature for annealing, hardening and tempering in an Electric furnace. Deep cryogenic treatment (DCT) was carried out on Cryocan at 77K. Various combinations of heat treatment cycles were performed to improve the mechanical properties of EN31 steel. This experimental also investigated the role of multiple cryogenic treatments before and after tempering. The findings show that Cryogenic treatment improves hardness, dimensional stability, and retained austenite to martensite and decreases residual stresses. This paper also studied and measured the hardness of various heat treated specimens using Brinell Hardness Tester.

Seiki Takahashi - One of the best experts on this subject based on the ideXlab platform.

  • development of apparatus for magnetic measurements of Charpy Impact Test pieces
    Journal of Materials Processing Technology, 2007
    Co-Authors: H Kikuchi, Mamoru Harada, Yasuhiro Kamada, Satoru Kobayashi, Seiki Takahashi
    Abstract:

    Abstract Since magnetic properties of ferromagnetic steels have a good correlation with their mechanical properties, those mechanical properties will be evaluated by magnetic measurements. An apparatus for measurement of BH curves of Charpy Impact Test pieces was therefore developed in order to evaluate the integrity of nuclear reactor pressure vessels nondestructively. In this paper, the operation of developed apparatus is demonstrated together with calibration of coercive field. It is also clarified that the evaluation of coercive field of the Charpy Impact Test pieces will be possible with an accuracy of better than 36 A/m. Additionally, a relation between the coercive field and the ductile–brittlement transition temperature is discussed.

  • Nondestructive Evaluation of Mechanical Property by Apparatus for Magnetic Measurements of Charpy Test Pieces
    IEEE Transactions on Magnetics, 2006
    Co-Authors: H Kikuchi, Mamoru Harada, Yasuhiro Kamada, Satoru Kobayashi, Seiki Takahashi
    Abstract:

    Since the magnetic and mechanical properties of steels are well correlated, the mechanical properties of steels can be evaluated by measuring their magnetic properties. Therefore, an apparatus for measuring the BH curves of Charpy Impact Test pieces was developed in order to nondestructively evaluate the integrity of nuclear reactor pressure vessels. In this study, the operation of the developed apparatus was confirmed and the relationship between the magnetic and mechanical properties of steels are discussed