巻号一覧
40 巻 (2014)
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40 巻, 4 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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研究論文
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吉村 彰記, 細谷 亮平, 小柳 潤, 小笠原 俊夫2014 年 40 巻 4 号 p. 146-152
発行日: 2014年
公開日: 2015/08/06
ジャーナル フリーIn this paper a new method which measures fiber orientation in CFRP laminates from X-ray CT images is proposed. In the proposed method, fiber orientation is analyzed by applying digital image correlation method (DIC) to the acquired tomographic images. By using DIC, brightness pattern, which results from radiodensity difference between fiber and resin, is compared between two different planes in thickness direction. Then three dimensional displacement of brightness pattern, which indicates fiber orientation, can be measured. In this study, we applied the proposed method to a quasi-isotropic CFRP laminate. After X-ray CT imaging, the sample was sectioned and polished. Fiber orientation was then experimentally measured by using a microscope. Fiber orientation calculated by the proposed method agrees very well with experimentally measured one, and the validity of the proposed method was demonstrated. Additionally, we applied the proposed method to a plane-woven CFRP laminate. The result revealed that the invalid fiber orientation may be calculated for the fiber orientation is parallel to the plane of CT image, or for the fiber orientation is calculated using the pattern around the outer edge of CT images.抄録全体を表示PDF形式でダウンロード (2805K) -
平野 義鎭, 草野 英昭, 青木 雄一郎2014 年 40 巻 4 号 p. 153-159
発行日: 2014年
公開日: 2015/08/06
ジャーナル フリーTensile fracture behaviour of CFRP laminate under varied strain rate is examined in this paper. In order to evaluate the fracture behaviour and surface strain distribution change, high-speed imaging technique and DIC (digital image correlation) is applied in combination. CFRP specimen having stacking sequence of [+45º/−45º]S and[90º]6T shows strain rate dependence though [0º]2T specimen does not show clear influence on tensile strength and failure strain. As a result of high-speed imaging, it is confirmed that fracture behaviour is scarcely affected by the strain rate despite of the strain rate dependency on strength and failure strain. By applying DIC to the high-speed photography taken just before the initiation of material failure, it is confirmed that the local strain concentration associated with inhomogeneous properties of the materials can be successfully capture.抄録全体を表示PDF形式でダウンロード (3208K) -
鈴木 尚之, 小柳 潤, 有川 秀一, 米山 聡2014 年 40 巻 4 号 p. 160-169
発行日: 2014年
公開日: 2015/08/06
ジャーナル フリーIdentification of mechanical properties of a unidirectional carbon fiber reinforced plastics is performed using virtual field method. Mechanical properties of the material can be obtained by the method based on principle of virtual work and actual displacement field of specimen surface. Actual displacement fields are measured using digital image correlation method. In the authors’ previous work, three-point bending test with relatively long-span was performed and mechanical properties were identified by the same procedure. In the paper, the identification in through-thickness direction was not good because accuracy of measurement of the strain in this direction was low in the test. In this study, actual displacement fields obtained two types of bending tests: short-span three-point bending and another bending test constrained at hyperstatic condition. Relationship between preciseness of the identification and test condition is discussed can obtain.抄録全体を表示PDF形式でダウンロード (2624K) -
石川 真志, 色川 千尋, 向後 保雄, 神谷 友裕, 宇都宮 真2014 年 40 巻 4 号 p. 170-179
発行日: 2014年
公開日: 2015/08/06
ジャーナル フリーIn this study, we investigated analytically and experimentally time-dependent deformation of CFRP sandwich panels with polymer foam core ROHACELL due to temperature change and moisture absorption and desorption. Tensile tests for the ROHACELLs were carried out before and after the moisture absorption using digital image correlation method, and we obtained stress–strain relationship in each condition. Surface deformations of sandwich panels were calculated by the finite element analyses considering the elasto-plastic constitutive equation of the ROHACELLs based on the tensile test results. Experimentally measured deformation in the sandwich panels after the moisture absorption was approximately 100μm. This was much larger than the analytical result. The deformations remained in after re-dry condition. On the basis of this study, we suggest that the main reason for the deformation in the sandwich panels could be irreversible shrinkage of the ROHACELLs caused by absorbing moisture during exposed in high temperature and high humidity environment.抄録全体を表示PDF形式でダウンロード (6533K) -
米山 聡, 小柳 潤, 有川 秀一2014 年 40 巻 4 号 p. 180-188
発行日: 2014年
公開日: 2015/08/06
ジャーナル フリーIn this paper, a method for evaluating discontinuous displacement and strain distributions using digital image correlation is proposed. A finite element mesh based digital image correlation method is utilized for measuring displacements taking into account displacement and strain discontinuities. Then, smoothed displacements are obtained and strains are computed from the measured displacements using finite element mesh again. Discontinuous strains can be obtained by the proposed method using a split finite element mesh. The effectiveness is validated by applying the proposed method to displacement and strain measurement of a triaxially woven fabric composite that has a lot of free boundaries, displacement measurement around a crack, and displacement and strain measurement around an interface in the dissimilar materials. Results show that the discontinuous displacement and strain distributions can be obtained by the proposed method. It is expected that the proposed method can be applied to experimental evaluation of various structures and members including displacement and strain discontinuities such as free boundaries, cracks and interfaces.抄録全体を表示PDF形式でダウンロード (2591K)
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