국내 최대 기계 및 로봇 연구정보

기술보고서

기술보고서 게시판 내용
타이틀	Analysis of Thermal Stress by Homogenization Method for SiC Coated Carbon-carbon Composites.
저자	Yoshio AOKI, Shuuji ENDO
Keyword
URL	http://send.nal.go.jp/send/jpn/dlpdf.php3/naltr0001435.pdf?id=NALTR0001435
보고서번호	NAL-TR-1435
발행년도	2002.1
출처	NAL (National Aerospace Laboratory of Japan)
ABSTRACT	Carbon-carbon composites coated with silicon carbide(SiC) were planned to be used as material for the thermal protection structures of space planes. However, residual thermal stress causeds many cracks in the SiC layer when cooled to room temperature after the CVD coating process at 1250℃. At the first step to prevent the nucleation of cracks, the residual thermal stress of the coated specimen was calculated by the finite element method, and it was found that the tensile stress in the SiC layer exceeded the tensile strength of SiC. To solve this problem, a 3D fabric composite consisting of SiC fiber in XY-plane, and carbon fiber in Z-direction was developed, which enabled the creation of an SiC coating without cracks in a 40 mm square specimen. The next step is the application of this composite to a large-scale structure and the reduction of the weight/strength ratio. To evaluate the stress of a structure made of this composite, a homogenization method which makes it possible to analyze the stress both in macroscopic and microscopic level was introduced to the finite element code. Thermal stress in the 40 mm squared specimen was calculated by this code, and it was confirmed that the homogenization method provided reasonable solutions for the experimental result.