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J F Kalthoff - One of the best experts on this subject based on the ideXlab platform.

  • characterization of the dynamic failure behaviour of a glass fiber vinyl ester at different temperatures by means of instrumented Charpy Impact Testing
    Composites Part B-engineering, 2004
    Co-Authors: J F Kalthoff
    Abstract:

    Instrumented Charpy Impact Testing is used to investigate the strength and failure properties of a glass-fiber/vinyl-ester composite. The test technique, originally developed for Testing of steel specimens, is presented in its basic aspects; reported are the conventional procedures for determining load, displacement and energy absorption that a specimen experiences, over the entire phase of loading and subsequent failure of the specimen. Techniques are described for generating data of sufficient accuracy when applying the test to composites. In particular, the necessity of utilizing measurement chains of sufficiently high frequency response and striker tups of sufficiently high sensitivity is emphasized. Tests are performed with glass-fiber/vinyl-ester specimens, provided with notches oriented in two different directions with respect to the plies of woven glass fiber rovings. Two different types of failure result: fiber breakage ahead of the notch due to tensile stresses, and delaminations of the interface planes between the plies of woven glass fiber rovings due to shear stresses. Specifically, energies absorbed by the specimen over the entire failure process and values of maximum load occurring during the Impact process are measured over a large range of temperatures. The data are correlated with the observed failure phenomena. The high level of information obtained in characterizing the failure behaviour by means of a test which requires limited technical effort proves the instrumented Charpy Impact test to be a simple but effective tool for quantifying the quality of a composite in practical applications, as e.g. in surveillance programs for controlling processes such as manufacturing or aging of the material.

  • Characterization of the dynamic failure behaviour of a glass-fiber/vinyl-ester at different temperatures by means of instrumented Charpy Impact Testing
    Composites Part B-engineering, 2004
    Co-Authors: J F Kalthoff
    Abstract:

    Instrumented Charpy Impact Testing is used to investigate the strength and failure properties of a glass-fiber/vinyl-ester composite. The test technique, originally developed for Testing of steel specimens, is presented in its basic aspects; reported are the conventional procedures for determining load, displacement and energy absorption that a specimen experiences, over the entire phase of loading and subsequent failure of the specimen. Techniques are described for generating data of sufficient accuracy when applying the test to composites. In particular, the necessity of utilizing measurement chains of sufficiently high frequency response and striker tups of sufficiently high sensitivity is emphasized. Tests are performed with glass-fiber/vinyl-ester specimens, provided with notches oriented in two different directions with respect to the plies of woven glass fiber rovings. Two different types of failure result: fiber breakage ahead of the notch due to tensile stresses, and delaminations of the interface planes between the plies of woven glass fiber rovings due to shear stresses. Specifically, energies absorbed by the specimen over the entire failure process and values of maximum load occurring during the Impact process are measured over a large range of temperatures. The data are correlated with the observed failure phenomena. The high level of information obtained in characterizing the failure behaviour by means of a test which requires limited technical effort proves the instrumented Charpy Impact test to be a simple but effective tool for quantifying the quality of a composite in practical applications, as e.g. in surveillance programs for controlling processes such as manufacturing or aging of the material.

D R G Achar - One of the best experts on this subject based on the ideXlab platform.

H Kurishita - One of the best experts on this subject based on the ideXlab platform.

  • specimen size effects on ductile brittle transition temperature in Charpy Impact Testing
    Journal of Nuclear Materials, 2004
    Co-Authors: H Kurishita, T Yamamoto, M Narui, H Suwarno, T Yoshitake, Y Yano, Masanori Yamazaki, H Matsui
    Abstract:

    Abstract One key issue for small specimen test techniques is to clarify specimen size effects on test results. In consideration of size effects on determining the ductile-to-brittle transition temperature (DBTT) in Charpy Impact Testing, a method to evaluate the plastic constraint loss for differently sized Charpy V-notch (CVN) specimens is proposed and applied to a ferritic–martensitic steel, 2WFK, developed by JNC. In the method, a constraint factor, α , that is an index of the plastic constraint is defined as α=σ ∗ /σ y ∗ . Here, σ ∗ is the critical cleavage fracture stress which is a material constant and σ y ∗ is the uniaxial yield stress at the DBTT at the strain rate generated in the Charpy Impact test. The procedures for evaluating each of σ ∗ and σ y ∗ are described and a result of σ ∗ and σ y ∗ , thus the value of α , is presented for different types of miniaturized and full-sized CVN specimens of 2WFK.

  • Specimen size effects on ductile?brittle transition temperature in Charpy Impact Testing
    Journal of Nuclear Materials, 2004
    Co-Authors: H Kurishita, T Yamamoto, M Narui, H Suwarno, T Yoshitake, Y Yano, Masanori Yamazaki, H Matsui
    Abstract:

    Abstract One key issue for small specimen test techniques is to clarify specimen size effects on test results. In consideration of size effects on determining the ductile-to-brittle transition temperature (DBTT) in Charpy Impact Testing, a method to evaluate the plastic constraint loss for differently sized Charpy V-notch (CVN) specimens is proposed and applied to a ferritic–martensitic steel, 2WFK, developed by JNC. In the method, a constraint factor, α , that is an index of the plastic constraint is defined as α=σ ∗ /σ y ∗ . Here, σ ∗ is the critical cleavage fracture stress which is a material constant and σ y ∗ is the uniaxial yield stress at the DBTT at the strain rate generated in the Charpy Impact test. The procedures for evaluating each of σ ∗ and σ y ∗ are described and a result of σ ∗ and σ y ∗ , thus the value of α , is presented for different types of miniaturized and full-sized CVN specimens of 2WFK.

  • Current status of small specimen technology in Charpy Impact Testing
    Journal of Nuclear Materials, 1994
    Co-Authors: H Kurishita, M Narui, Hideo Kayano, Masanori Yamazaki
    Abstract:

    Abstract The current status of small-scale specimen technology in Charpy Impact Testing for ferritic steels is presented, with emphasis on the effect of the notch dimensions (notch depth, notch root radius and notch angle) on the upper shelf energy (USE) and ductile-to-brittle transition temperature (DBTT). The USE for miniaturized specimens, normalized by Bb 2 or ( Bb 3 2 ( B is the specimen thickness, b the ligament size), is essentially independent of notch geometry and has a linear relationship with the USE of full size specimens, regardless of irradiation and alloy conditions. The DBTT of miniaturized specimens depends strongly on the notch dimensions; this dependence of the DBTT decreases as the DBTT of full size specimens increase due to neutron irradiation or thermal aging. These results may be useful in determining the USE and DBTT for full size specimens from those for miniaturized specimens.

  • effects of v notch dimensions on Charpy Impact test results for differently sized miniature specimens of ferritic steel
    Materials Transactions, 1993
    Co-Authors: H Kurishita, M Narui, Masanori Yamazaki, Hideo Kayano, Yoichi Kano, Itaru Shibahara
    Abstract:

    In order to develop the small specimen technology in Charpy Impact Testing, the effects of V-notch dimensions on the test results were investigated for miniaturized specimens of a ferritic steel, Japanese Ferrite/Martensite Dual Phase Steel (JFMS). The miniaturized Charpy specimens had four different square cross-sections of 3.3, 2, 1.5 and 1 mm, and each of them had a variety of V-notch dimensions (notch depth, notch root radius and notch angle). All of the specimens were subjected to Charpy Impact tests between 93 and 373 K using a specially instrumented Impact machine. The fracture surfaces of all tested specimens were examined by scanning electron microscopy

  • Charpy Impact Testing using miniature specimens and its application to the study of irradiation behavior of low activation ferritic steels
    Journal of Nuclear Materials, 1991
    Co-Authors: Hideo Kayano, H Kurishita, M Narui, Masanori Yamazaki, A Kimura, Yoshimitsu Suzuki
    Abstract:

    Abstract The effectiveness of mini-size Charpy V-notch specimens with a 1.5 or 1.0 mm square cross section in measuring the ductile brittle transition temperature (DBTT) and upper shelf energy (USE) compared with full-size specimens is evaluated for a ferritic steel. It is shown that the data from the mini-size specimens can be used to estimate the DBTT and USE for full-size specimens when the measured absorbed energy-temperature curves are normalized by appropriate parameters. The result is applied to the study of neutron irradiation embrittlement of low-activation ferritic steels.

Norman Mcpherson - One of the best experts on this subject based on the ideXlab platform.

  • development of a process envelope for friction stir welding of dh36 steel a step change
    Materials & Design, 2014
    Co-Authors: Athanasios Toumpis, Alexander Galloway, Stephen R Cater, Norman Mcpherson
    Abstract:

    Friction stir welding of steel presents an array of advantages across many industrial sectors compared to conventional fusion welding techniques. However, the fundamental knowledge of the friction stir welding process in relation to steel remains relatively limited. A microstructure and property evaluation of friction stir welded low alloy steel grade DH36 plate, commonly used in ship and marine applications has been undertaken. In this comprehensive study, plates of 2000 x 200 x 6 mm were butt welded together at varying rotational and traverse speeds. Samples were examined microscopically and by transverse tensile tests. In addition, the work was complemented by Charpy Impact Testing and micro-hardness Testing in various regions of the weld. The study examined a wide range of process parameters; from this, a preliminary process parameter envelope has been developed and initial process parameter sets established that produce commercially attractive excellent quality welds through a substantial increase in the conventionally recognised weld traverse speed.

Douglas C Hofmann - One of the best experts on this subject based on the ideXlab platform.

  • cryogenic Charpy Impact Testing of metallic glass matrix composites
    Scripta Materialia, 2012
    Co-Authors: Scott N Roberts, Carl Zachrisson, Adam Ullah, Henry Kozachkov, Andrew A Shapiro, William L Johnson, Douglas C Hofmann
    Abstract:

    Compact Charpy Impact Testing was employed to investigate the effect of low temperatures on the Impact toughness of bulk metallic glass matrix composites (BMGMCs). Samples were fabricated via suction casting and Impacted from room temperature down to liquid nitrogen temperature. Unlike monolithic glasses, BMGMCs do exhibit a steep decrease in toughness as the temperature is reduced from the ambient, caused by embrittlement in the ductile reinforcing phase. However, at cryogenic temperatures, BMGMCs have a toughness equivalent to their glassy matrix.

  • Effect of processing on Charpy Impact toughness of metallic glass matrix composites
    Journal of Materials Research, 2011
    Co-Authors: Carl Zachrisson, Henry Kozachkov, William L Johnson, Scott Roberts, Georg Kaltenboeck, Robert D. Conner, Marios D. Demetriou, Douglas C Hofmann
    Abstract:

    In this study, compact Charpy Impact Testing was used to investigate the effect of processing history and dendrite morphology of bulk metallic glass matrix composites (BMGMCs) on Impact toughness. Composite samples were fabricated via suction casting and semisolid forging, and the results were compared with crystalline alloys in the same geometry. A strong dependence on processing was observed, with samples exhibiting up to a 30-fold increase in Impact toughness depending on processing and microstructure. Provided that attention is paid to processing techniques, BMGMCs are shown to have properties that equal or surpass some conventionally used crystalline alloys. These properties invite further exploration of these materials in structural applications.