巻号一覧
30 巻 (2004)
- 6 号 p. 219-
- 5 号 p. 175-
- 4 号 p. 135-
- 3 号 p. 91-
- 2 号 p. 45-
- 1 号 p. 1-
30 巻, 5 号
選択された号の論文の5件中1～5を表示しています
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島村 佳伸, 占部 貴之, 轟 章, 小林 英男2004 年 30 巻 5 号 p. 175-181
発行日: 2004/09/15
公開日: 2009/08/11
ジャーナル フリーHealth monitoring techniques for CFRP composite structures have been developed to assure the structural integrity. Electric impedance method is cost-effective and easy to apply for various structures. In order to apply the method to actual environment, the influence of moisture absorption on the electric impedance change of CFRP can not be neglected. In this paper, the influence of moisture absorption is investigated experimentally. The electric impedances both in the fiber direction and transverse direction are measured during moisture absorption. For both directions, it is found the electric impedance increases with moisture absorption. Furthermore, a monitoring method of moisture absorption rate near surface is proposed and experimentally investigated. As a result, it is shown that the change of the electric impedance follows the change of moisture absorption ratio near the surface.抄録全体を表示PDF形式でダウンロード (781K) -
島村 佳伸, 宮本 善治, 轟 章, 小林 英男2004 年 30 巻 5 号 p. 182-191
発行日: 2004/09/15
公開日: 2009/08/11
ジャーナル フリーStiffener/skin structures in integrated composite parts suffer debonding between stiffener and skin due to loading. Application of fracture mechanics to assess structural integrity of the integrated composite parts is difficult because of complexity of the structural configuration and inhomogeneity of composite materials. A simulation method to assess the structural integrity that predicts onset and growth of debonding and estimates the stiffness degradation due to debonding is needed. In this study, a simulation method based on FEM is investigated for stiffener/skin structures. The simula-tion method is intended to be versatile and easy to implement for commercial FEM codes. Stiffener/skin structures are modeled as cohesion of shell elements. If debonding is judged by an energy release rate criterion, the cohesion is released. Delamination growth in a DCB specimen and an ELS specimen is simulated and compared with theoretical and experimental results to demonstrate the feasibility. Thus, the debonding of stiffener/skin structures is simulated, and is reproduced success-fully by the proposed method.抄録全体を表示PDF形式でダウンロード (3410K) -
民秋 実, 藤井 透, 大窪 和也2004 年 30 巻 5 号 p. 192-198
発行日: 2004/09/15
公開日: 2009/08/11
ジャーナル フリーA sandwich panel with urethane core and GFRP skin plate was developed for the lorry floor. Small spherical bumps were found at a relatively short period in the skin plate along the trail of cart wheels. Fatigue tests were conducted to simulate the wake of the bumps using an apparatus with a wheel pressed onto the surface of sample panels, which were being moved back and forth. After 1, 000 cycles, one or two small bumps were observed along the trail. After fabricating a sandwich panel, spherical bumps were also found in the skin plate at locations where release films were glued on the back surface of the skin plate. The size of bumps increased as the stiffness of the urethane core being high. The mechanism of the bump formation in the skin plate is elucidated as follows: Residual compressive stress exists in the skin plate due to contraction of the core material during consolidation. A crack is initiated in the core closest to the skin plate due to a high moving load by the wheel. Thereafter, the crack grows along the skin plate with an increase of loading cycles. As the delaminated area increases, an out-of-plane deformation of the skin plate occurs due to the residual compressive stress in the skin plate. Finally, a process based on the residual stress relaxation to eliminate such a wake of bumping was proposed.抄録全体を表示PDF形式でダウンロード (907K) -
岡部 洋二, 辻 良平, 武田 展雄2004 年 30 巻 5 号 p. 199-206
発行日: 2004/09/15
公開日: 2009/08/11
ジャーナル フリーFiber Bragg grating (FBG) sensors are usually used for the measurement of axial strain. However, when a non-axisymmetric transverse strain is applied to the FBG sensor, the reflection spectrum from the sensor splits into two peaks because of the birefringence effect. Using this phenomenon, in this research, the FBG sensor was applied to the measurement of transverse thermal residual strain in CFRP laminates. First, the FBG sensor was compressed transversely in order to investigate the deformation of the reflection spectrum due to the birefringence effect. The wave-length shifts of the two peaks in the spectrum agreed with those calculated theoretically. Then, the FBG sensor was embedded into a CFRP cross-ply laminate, and the wavelength shifts of the two peaks were measured as the temperature of the laminate was changed. From the peak wavelengths, the non-axisymmetric component of the thermal residual strain in the laminate could be obtained in consideration of the birefringence effect and the strain transfer from the laminate to the optical fiber. Furthermore, the effect of the fiber coating on the measurement sensitivity was clarified theoretically.抄録全体を表示PDF形式でダウンロード (3113K) -
後藤 健, 八田 博志, 西山 勇一, 樋口 太郎, 杉林 俊夫2004 年 30 巻 5 号 p. 207-213
発行日: 2004/09/15
公開日: 2009/08/11
ジャーナル フリーSpin burst tests of carbon-carbon (C/C) rings were carried out to confirm fracture criterion under high speed rotation as a function of the inner/outer diameter ratio R. The C/C rings were of a quasi-isotropic lamination type and were confirmed to have isotropic strength by static tensile tests. The burst rotation speeds of the C/C rings were found to be much lower than those expected from stress distributions. Detailed inspection of stress distributions in the C/C rings revealed that rotational unbalance inherent in C/Cs caused high average hoop stress and stress concentration at around inner radius. These effects were shown to lower fracture rotation speeds.抄録全体を表示PDF形式でダウンロード (829K)
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