著者

上田 政人 平賀 淳人 西村 哲

出版者

The Japan Society for Composite Materials

雑誌

日本複合材料学会誌 (ISSN:03852563)

巻号頁・発行日

vol.37, no.3, pp.103-110, 2011 (Released:2012-02-25)

参考文献数

23

被引用文献数

4 4

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Micro-buckling characteristic of a carbon mono-fiber in matrix was studied. A fiber was modeled in matrix as a column on elastic foundation. Buckling stress of the fiber was calculated incorporating the initial fiber misalignment and non-linearity of the matrix. The effect of bending on compressive stress was also taken into considered to estimate failure initiation at fiber surface. Two processes of ultimate fiber failure were considered. First one is a compressive fracture at fiber surface due to compression and bending. Second one is a matrix-yielding initiated unstable fiber deformation. Compression test of a carbon fiber in matrix was performed by means of a four point bending test. Electrical resistance of the carbon fiber was measured during the compression test to recognize initiation of the compressive fracture. Fiber breaks at two adjacent locations were observed, which was caused by micro-buckling of the fiber. Apparent compressive strength of the fiber was measured in the experiment. Actual compressive strength of the fiber was predicted from the apparent compressive strength. Correlation between compressive strengths based on the elastic foundation model and the kink band model was discussed.

著者

本間 正葵 加藤 保之 上田 政人

出版者

一般社団法人日本機械学会

雑誌

年次大会講演論文集 : JSME annual meeting

巻号頁・発行日

vol.2009, no.1, pp.53-54, 2009-09-12

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A research program for investigating the thermo-elasto-plastic behavior when a laser beam is irradiated to the surface of a thin metal plate with cooling its backside is described in this paper. The residual deformation and the residual internal force occur in a thin plate after the cooling process. Therefore the plastic analyses for the second and third irradiation are more complicated. Based on the radial flow rule, the deformation increments can be decomposed into an elastic component and plasticity component on the interaction curve. In this paper, the plastic analysis for the third irradiation, which is obtained after the first and the second irradiation were performed, is treated. Especially, the distributions of the residual internal forces obtained after cooling process for the third irradiation are revealed.

著者

轟 章 大浅田 樹 水谷 義弘 鈴木 良郎 上田 政人 松崎 亮介 平野 義鎭

出版者

一般社団法人 日本複合材料学会

雑誌

日本複合材料学会誌 (ISSN:03852563)

巻号頁・発行日

vol.45, no.4, pp.141-148, 2019-07-15 (Released:2020-07-29)

参考文献数

11

被引用文献数

1

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Continuous carbon fiber composites can be printed with 3D printers. Many studies detailing elucidations of the mechanical properties of such 3D printed composites have been published, all of which employed a conventional tensile specimen configuration with surface resin layers. In the present study, 0º, 90º, ±45º, and lay-up direction type specimens were newly designed for 3D printed composites without surface layers. Using the 3D printer, both conventional and newly designed specimens with serpentine folded fiber bundles were fabricated and investigated experimentally. The lay-up direction specimen was fabricated using 800 layers. The specimens without the serpentine folded fiber bundles were experimentally shown to be adequate for tensile tests. The lay-up direction specimen had the lowest strength and stiffness, which seems to be related to its surface roughness.

著者

上田 政人 高嶋 豊士 加藤 保之 西村 哲

出版者

日本複合材料学会

雑誌

日本複合材料学会誌 (ISSN:03852563)

巻号頁・発行日

vol.36, no.3, pp.104-111, 2010 (Released:2011-03-05)

参考文献数

31

被引用文献数

1 1

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Progressive crushing tests of unidirectionally laminated carbon fiber reinforced plastic (CFRP) rectangular plate were carried out to reveal its continuous fracture behavior and energy absorption. A special test fixture was developed for the test and fracture process of the CFRP was observed from its side section. Three types of trigger geometries, i.e. chamfer, steeple and V-shape trigger, were machined on each specimen. Film embedded V-shape trigger was also prepared to investigate the effect of initial cracks on energy absorption. The initial fracture behavior strongly affected the ensuing stable fracture process. It was clarified that V-shape trigger specimen was robust over the variation of gage length (unsupported length) as compared to chamfer and steeple trigger specimen which showed smaller energy absorption with longer gage length. A column-like part, which was called pillar in this paper, was observed between fronds under crushing. The fracture was much severe at pillar section than fronds section. Fiber fractures were observed periodically at 50-100 μm length in the pillar section, which coincides with the length of kink band in ultimate compressive failures of CFRP. It was revealed that the thickness of pillar was dominant factor on energy absorption of unidirectional CFRP.