<p>The reentry capsule is one of the key technologies to support the sample return mission from deep space. The optimization of heat shield design is essential to meet to the weight limit of a reentry capsule, and one of approach to reduce its weight includes an exact predction of the aerodynamic heating environment at the rear heat shield. As an observation of the rear heat shield of "Hayabusa" reentry capsule, overlapped part of single side aluminized polyimide tape remained after the capsule returned to the earth. This fact shows that the actual heat flux during reentry on the rear was much lower than the assumption for heat shield design. In this paper, the heat flux on the rear was identified by the heating tests of the polyimide tape on the ablators using ICP heater. The result indicates that the heat flux on the rear heat shield is less than 20% of the assumption in the design of "Hayabusa" capsule. Furthermore, one dimensional thermal conduction analysis on the similar structure of the rear heat shield was carried out on the basis of its experimental estimation. The results of this analysis show the possibility that the thickness of ablator material for the rear heat shield may be reduced to half at the maximum.</p>
1 0 0 0 OA X線CT画像を用いたCFRP積層板の繊維方向測定
- 著者
- 吉村 彰記 細谷 亮平 小柳 潤 小笠原 俊夫
- 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.40, no.4, pp.146-152, 2014 (Released:2015-08-06)
- 参考文献数
- 8
- 被引用文献数
- 2
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.
1 0 0 0 OA CFRP積層板における層の配向誤差による面外変形(積層構成の熱変形に対する影響)
- 著者
- 荒尾 与史彦 小柳 潤 武田 真一 宇都宮 真 川田 宏之
- 出版者
- 一般社団法人 日本機械学会
- 雑誌
- 日本機械学会論文集A編 (ISSN:18848338)
- 巻号頁・発行日
- vol.77, no.776, pp.619-628, 2011 (Released:2011-04-25)
- 参考文献数
- 17
- 被引用文献数
- 7 8
Strict geometrical stability is required for the precise structures like telescopes. Unpredictable out-of-plane deformation is a serious problem when we use CFRP (Carbon Fiber Reinforced Plastic) laminate to the precise structure. This out-of plane deformation of symmetrical CFRP laminate mainly arise from combination effects of ply angle misalignment and temperature change. We discussed here is effective stacking sequence of CFRP laminate that mitigate the deformation caused by the ply angle misalignment. The analysis based on laminate theory was performed to calculate the thermal deformation. In this analysis, the random numbers were added to each layers as ply angle misalignments. The analytical results were obtained statistically by Monte Carlo method. Mohr's curvature circle was also incorporated to evaluate the deformation as P-V (peak to Valley) values. We performed the analysis with various stacking sequence. It was calculated that the symmetric cross-ply laminates deformed 10 times larger than the other quasi-symmetric laminates. In the case of the total ply number is less than 12, the stacking sequence in the laminate has a significant effects on the thermal deformation. However, if the total number ply number is more than 24, effect of stacking sequence on the thermal deformation becomes negligible. We also discussed the geometrical stability of CFRP mirror by considering unavoidable ply angle misalignment. It was presumed that the CFRP mirror can be used for wide range of wave length when the back structure was attached to CFRP laminates.