Journal of the Japan Society for Composite Materials

Comparisons of Strengths and Damage Evolutions of a Pin Joint in CFRP Laminates under Fatigue and Quasi-Static Tensile Loading

Satoshi SEIKE, Yoshihiro TAKAO, Wen-Xue WANG, Terutake MATSUBARA

2007 Volume 33 Issue 5 Pages 161-169
Published: September 15, 2007
Released on J-STAGE: August 11, 2009

DOIhttps://doi.org/10.6089/jscm.33.161

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A mechanically fastened joint in Carbon Fiber Reinforced Plastic (CFRP) laminates is necessary for its advantages in inspection, replacement and reliability, nevertheless its disadvantage in stress concentration. The mechanical joint should be designed to make the bearing failure mode occur because the strength is high and the joint fails non-catastrophically, while it fails catastrophically in other tensile and shear-out modes. In this study, the damage evolution of the pin joints for both [0/±45/90]_3S and [90/±45/0]_3S CFRP laminates and its difference between static and fatigue loading were discussed in detail. No difference between the macroscopic external appearance of damaged specimens under fatigue and static loading was observed, but the microscopic internal damage differed in critical damage and evolution. In static tests all the inside 0° layers had kinking at the maximum load and the kinking to be a trigger to the final failure with intense delamination and matrix crack. On the other hand, under fatigue loading the final damages mostly started from collapse at the loaded surface edge. It was also found that the total delamination length was longer in the case of fatigue at the same total matrix crack length and that [90/±45/0]_3S presented higher strength than [0/±45/90]_3S in both static and fatigue cases.

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Finite Element Analysis for Microscopic Damage in Single-Fiber Composites Using a Cohesive Zone Model

Masaaki NISHIKAWA, Tomonaga OKABE, Nobuo TAKEDA

2007 Volume 33 Issue 5 Pages 170-177
Published: September 15, 2007
Released on J-STAGE: August 11, 2009

DOIhttps://doi.org/10.6089/jscm.33.170

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This paper numerically investigates the microscopic damage in a single-fiber composite (SFC). A cohesive zone model (CZM) is presented to investigate the typical microscopic damages observed in the SFC. The CZM clarifies that the behavior of interfacial debonding, which influences significantly on the axial stress recovery of the embedded fiber, is greatly affected by matrix plasticity and cracking. We conduct a Monte-Carlo simulation for the fragmentation of the embedded fiber. The Monte-Carlo simulation demonstrates that these microscopic damages are important factors in the fragmentation of the embedded fiber. These simulated results are also compared with analytical models. These discussions reveal that the fragmentation process in an embedded fiber is controlled by the cohesive parameters of the fiber/matrix interface.

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[title in Japanese]

Fujio ITANI

2007 Volume 33 Issue 5 Pages 178-187
Published: September 15, 2007
Released on J-STAGE: August 11, 2009

DOIhttps://doi.org/10.6089/jscm.33.178

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[title in Japanese]

Kazuhiko KOSUGE

2007 Volume 33 Issue 5 Pages 188-190
Published: September 15, 2007
Released on J-STAGE: August 11, 2009

DOIhttps://doi.org/10.6089/jscm.33.188

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[title in Japanese]

Yukihiro NOMURA

2007 Volume 33 Issue 5 Pages 191-195
Published: September 15, 2007
Released on J-STAGE: August 11, 2009

DOIhttps://doi.org/10.6089/jscm.33.191

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[title in Japanese]

Koichi GODA

2007 Volume 33 Issue 5 Pages 196-201
Published: September 15, 2007
Released on J-STAGE: August 11, 2009

DOIhttps://doi.org/10.6089/jscm.33.196

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