Journal of the Japan Society for Composite Materials
Online ISSN : 1884-8559
Print ISSN : 0385-2563
ISSN-L : 0385-2563
Volume 10, Issue 4
Displaying 1-6 of 6 articles from this issue
  • Shigeyuki AKIHAMA
    1984 Volume 10 Issue 4 Pages 145-151
    Published: October 31, 1984
    Released on J-STAGE: August 11, 2009
    JOURNAL FREE ACCESS
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  • Keiichi KUNIYA, Hideo ARAKAWA
    1984 Volume 10 Issue 4 Pages 152-156
    Published: October 31, 1984
    Released on J-STAGE: August 11, 2009
    JOURNAL FREE ACCESS
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  • Y. OZAWA, H. SEKINE
    1984 Volume 10 Issue 4 Pages 157-162
    Published: October 31, 1984
    Released on J-STAGE: August 11, 2009
    JOURNAL FREE ACCESS
    The interfacial debonding is observed in the earliest stage of damage in dispersed composite materials. The crack initiation into a matrix from the ends of partially debonded surfaces of dispersed inclusions plays an important role in the estimation of strength of dispersed composite materials. The criteria discussed in this paper are as follows : (1) the maximum hoop stress criterion, (2) the minimum strainenergy density criterion, (3) the maximum energy-release-rate criterion and (4) the maximum principal stress criterion. These criteria were based on the singular stress field at the ends of debonded surfaces. Tension tests were performed by using epoxy resin specimens containing a flat steel inclusion. By examining the experimental results, it was found that (1) the maximum hoop stress criterion, (2) the minimum strain-energy density criterion and (4) the maximum principal stress criterion are appropriate as the criteria for crack initiation when the matrix is subjected to tensile stress in the direction of the flat inclusion. However the maximum energy-release-rate criterion is invalid.
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  • M. SUZUKI, H. NAKANISHI, M. IWAMOTO, S. ARAKI, S. MUNEMURA, A. NAKANIS ...
    1984 Volume 10 Issue 4 Pages 163-170
    Published: October 31, 1984
    Released on J-STAGE: August 11, 2009
    JOURNAL FREE ACCESS
    The method to determine the stable crack initiation point of R-RIM polyurethane by three point bending test is proposed and the value of crack tip opening displacement at this point is studied by using the relation between the rotational factor and the crack tip displacement with a concept of fracture mechanics. The critical crack tip opening displacement can be confirmed by continuous observation of the crack blunting and the following stable crack growth processes. It is found that critical value for specimen with the fiber weight content of ten percent is larger than that of zero percent, and the critical value for specimen with void content of sixteen percent is larger than those of three and ten percent. The results can be explained by an increase of the deformation in resin part due to the fiber reinforcement at the crack tip and the ductile deformation in resin part between the notch and the voids.
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  • T. FUKUDA, T. FUJII
    1984 Volume 10 Issue 4 Pages 171-178
    Published: October 31, 1984
    Released on J-STAGE: August 11, 2009
    JOURNAL FREE ACCESS
    A desk-top computer (what we call a personal computer) system was on-line used connecting a conventional material testing machine to evaluate the low-cycle fatigue response of glass-mat FRP. During the fatigue test, the strain behavior can be monitored by a large-strain gage put between layers when the specimen is made by the hand lay-up method. As a test result, the fatigue damage of the specimens under high stress levels of 90-75% of the static tensile strength can he characterized by the fact that the ratio of the plastic strain to the total strain increases approximately linearly with the logarithm of the repeated cycle. Using such an information of the computer monitoring, the prediction test of the cycle to failure of the specimen was carried out by on-line use of the computer system. The prediction results were compared with the experimental data. In addition, the fatigue life of the mat FRP in the low-cycle region of less than 200 cycles was evaluated by applying a statistical approach based on the Weibull distribution. The statistical analysis shows that the dispersion of the fatigue life is remarkably large and larger for the higher applied stress level, while the dispersion of the static tensile strength of the specimen is comparatively small.
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  • 1984 Volume 10 Issue 4 Pages 180-182
    Published: October 31, 1984
    Released on J-STAGE: February 08, 2010
    JOURNAL FREE ACCESS
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