Journal of the Japan Society for Composite Materials
Online ISSN : 1884-8559
Print ISSN : 0385-2563
ISSN-L : 0385-2563
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Volume 29, Issue 6
Displaying 1-6 of 6 articles from this issue
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  • [title in Japanese]
    Takuji KOYANAGI
    2003 Volume 29 Issue 6 Pages 205-209
    Published: November 15, 2003
    Released on J-STAGE: August 11, 2009
    DOIhttps://doi.org/10.6089/jscm.29.205
    JOURNAL FREE ACCESS
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  • [title in Japanese]
    Yoshiro SHOJI
    2003 Volume 29 Issue 6 Pages 210-216
    Published: November 15, 2003
    Released on J-STAGE: August 11, 2009
    DOIhttps://doi.org/10.6089/jscm.29.210
    JOURNAL FREE ACCESS
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  • Effects of Loading History on Electric Resistance in CFRP Unidirectional Composites
    Keiji OGI, Yoshihiro TAKAO
    2003 Volume 29 Issue 6 Pages 217-225
    Published: November 15, 2003
    Released on J-STAGE: August 11, 2009
    DOIhttps://doi.org/10.6089/jscm.29.217
    JOURNAL FREE ACCESS
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    The effect of loading history on the electric resistance in CFRP unidirectional composites was experimentally investigated. First, monotonic tensile tests were conducted for on-axis and off-axis unidirectional specimens to measure the change in the electric resistance together with strain up to failure. The initial gage factor was theoretically derived from piezoresistivity as a function of the off-axis angle and was compared with the experimental results. Next, loading/unloading tensile tests as well as fatigue tests at low load levels were performed to measure the change in the electric resistance due to loading history. It was found that the electric resistance-strain curves for monotonic tensile loading exhibit nonlinear behavior after the linear region, and that the gage factor becomes negative at high strains for some off-axis directions. The initial gage factor becomes the maximum at the angle of 12 degrees according to the present model, and the predicted gage factors are in reasonably good agreement with the experimental ones. The permanent change in the electric resistance, which is not always ascribed to damage, was observed in all the directions after the loading/unloading as well as the fatigue loading.
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  • Damage Analysis of CFRP Plates Exposed to Cryogenic Shock by AE Monitoring
    Yoshihiro MIZUTANI, Taketo HIRATSUKA, Hidenori TANABE, Mikio TAKEMOTO
    2003 Volume 29 Issue 6 Pages 226-233
    Published: November 15, 2003
    Released on J-STAGE: August 11, 2009
    DOIhttps://doi.org/10.6089/jscm.29.226
    JOURNAL FREE ACCESS
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    In order to investigate fracture modes and timing for two types of CFRP plates during cryogenic shock testing, Acoustic Emission (AE) monitoring was conducted. No damage was observed for the specimen that made of heat-resistant matrix, however, thirty-nine matrix cracks were observed for the other specimen. Several cracks were observed even at the location where temperature differences on both surfaces were small. The AE signals were classified into three types by waveform characteristics according to the damage behavior. After that, three fracture modes of matrix crack, delamination and transverse cracks were simulated by pulse-laser irradiation to the CFRP plate and the detected AE signals were compared to estimate those obtained at cryogenic shock testing. The number of the AE signals linearly increased untill the LN2 disappeared from the cooling cell. Then, we conducted the vertical immersion test to examine the influence of cooling temperature to the damage occurrences. At temperatures lower than 228K, matrix cracks initiated at the specimen surface. At 213K, large number of AE signals due to matrix crack and few number of AE signals due to delamination and transverse crack were observed. At 77K, large number of AE signals caused by three types of fractures was detected.
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  • An Interface Element with Continuous Traction to Analyze Delamination Propagation
    Osamu MAJIMA, Hiroshi SUEMASU
    2003 Volume 29 Issue 6 Pages 234-241
    Published: November 15, 2003
    Released on J-STAGE: August 11, 2009
    DOIhttps://doi.org/10.6089/jscm.29.234
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    An interface element, taking account of both the material strengths and the fracture characteristics, is proposed to numerically simulate the damage propagation process in composite laminates. Several refinements are examined for the element to ensure the smooth convergence of the solution during the calculation of the damage when incorporated in the commercially available finite element package program (MARC) through user subroutine. The element has been successfully applied to a fundamental problem of the stable crack propagation and the crack initiation. Propagation process of multiple interlaminar delaminations in circular axi-symmetric nonlinear plates subjected to a quasi-static transverse load has been solved to demonstrate the applicability and efficiency of the present element to a complex delamination propagation problem. As continuous stress distribution with respect to the surface separation along the crack path are assumed on the interface, smooth and stable convergence of the solution of the crack propagation can be realized with fairly coarse mesh compared to the modeling where discrete interface traction force is assumed only at the nodes on the interface. Since the element would be taking into account the dissipated energy during the formation of crack surface, it can be applied to the simulation of dynamic failure process.
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  • Erratum
    2003 Volume 29 Issue 6 Pages 243
    Published: 2003
    Released on J-STAGE: February 08, 2010
    DOIhttps://doi.org/10.6089/jscm.29.243
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