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Volume 20 (1994)
- Issue 6 Pages 215-
- Issue 5 Pages 173-
- Issue 4 Pages 131-
- Issue 3 Pages 91-
- Issue 2 Pages 57-
- Issue 1 Pages 1-
Volume 20, Issue 3
Displaying 1-4 of 4 articles from this issue
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Kazumasa GOTOH, Hideki ISHIDA1994 Volume 20 Issue 3 Pages 91-98
Published: June 15, 1994
Released on J-STAGE: August 11, 2009
JOURNAL FREE ACCESSDownload PDF (941K) -
M. SHIWA, T. KISHI1994 Volume 20 Issue 3 Pages 99-107
Published: June 15, 1994
Released on J-STAGE: August 11, 2009
JOURNAL FREE ACCESSA new acoustic emission (AE) analysis method for fiber reinforced composite material was developed. Phase combinations of first arrival quasi-longitudinal wave of AE in plate (Lamb wave) was analyzed based on AE spherical radiation pattern in infinite homogeneous medium, plate wave propagation properties and detection properties of piezoelectric AE sensor. Angle ply carbon fiber/epoxy composites were prepared to the AE and Ultrasonic C-scope tests to evaluate the fracture processes of delamination. Three stages characterized both the compliance and the AE properties were observed during tensile tests. The spherical AE radiation pattern analysis could distinguish into three types of fracture mode for detected AE events, such as tensile fracture, shear fracture and mixture fracture of tensile and shear. By analyzing the AE spherical pattern events, C-scope, surface and fracture surface observation, fracture processes of the angle ply CFRP were proved. At stage I of which is linear load-strain region, debondings occurred at notch tip along the fiber orientation of each layer as shear fracture. At stage II of which is transient region between stage I and III, coalescence of the debonding in each layer occurred as tensile fracture. At stage III of which is heavy increase of the compliance and the AE counts region, the debonding and the coalescence occurred at the same time along the fiber orientation.View full abstractDownload PDF (4697K) -
M. SHIWA, N. TAKEDA, T. KISHI1994 Volume 20 Issue 3 Pages 108-115
Published: June 15, 1994
Released on J-STAGE: August 11, 2009
JOURNAL FREE ACCESSStructural dispersion and materials dispersion properties of acoustic emission wave on carbon fiber reinforced plastics (CFRP) cross ply plate (0/90°) was evaluated as a function of distances, the fiber orientations and the directions of AE wave propagation using a pencil lead breaking simulate source and resonant type of AE sensor. In case of the structural dispersion, when a main detected frequency range was under 50 kHz, the quasi-longitudinal wave (QL) could be approximated to a longitudinal wave of one dimension. While, the quasi-transverse wave (QT) indicated strong structural dispersion that were shown phase transition of peak amplitude of the wave packet as a function of propagation distance. As regards materials despersion, velocity of wave front in the QL depended on both a wave propagated in the fiber bundles and a through pass of the wave. In the case of attenuation properties, the QL was observed strong variety with the detected frequency range and the direction of wave propagation. While, that of the QT was observed variably. In the case of power spectrum of wave packet, as peak frequency of these waves indicated different with the resonant frequency of the sensor, we have to consider the dispersion properties of composite plate in addition the response properties of AE sensor.View full abstractDownload PDF (889K) -
C. MASUDA, Y. TANAKA, M. YAMAMOTO, M. FUKAZAWA1994 Volume 20 Issue 3 Pages 116-126
Published: June 15, 1994
Released on J-STAGE: August 11, 2009
JOURNAL FREE ACCESSFatigue crack propagation properties and fracture mechanisms were examined for three commercially fabricated aluminum matrix composites containing SiC whiskers (SiCw) and SiC particles (SiCp) under rotating bending condition. Fatigue crack propagation rates for SiCw/A2024 and SiCp/A356 composites were lower than those for unreinforced alloys at a given stress intensity factor near fatigue threshold, while the fatigue thresholds for those composites were higher than those for matrix alloys. For SiCp/A357 composite the fatigue crack propagation rates were higher than those for SiCp/A356 composite. Fractography revealed that the fatigue crack would propagate to the whisker/matrix interface following the formation of dimple patterns in the whisker rich zones or formation of striation patterns in the whisker poor zones for SiCw/A2024 composites, while for SiCp/A356 and SiCp/A357 composites the fatigue crack would propagate in the matrix near fatigue threshold . The near final failure crack would be linked to the sub-crack initiated from the particles ahead of the main crack. The fatiguecrack propagation models were proposed for discontinuous fiber reinforced aluminum matrix composites. It is suggested that the silicon carbide whiskers or particles would have a very significant effect on fatigue crack propagation properties near fatigue threshold.View full abstractDownload PDF (10594K)
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