Paper number 172


Takahira Aoki1, Takashi Ishikawa2, Hisashi Kumazawa1, and Yoshiki Morino3

1Department of Aeronautics and Astronautics, University of Tokyo
7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
2Airframe Division, National Aerospace Laboratory (NAL)
6-13-1 Ohsawa, Mitaka, Tokyo 181-0015, Japan
3National Space Development Agency of Japan (NASDA)
2-1-1 Sengen, Tsukuba, Ibaraki 305-8505, Japan

Summary The basic mechanical characteristics of carbon fiber reinforced plastics (CFRP) material systems are experimentally evaluated to discuss their applicability to the cryogenic propellant tanks of future reusable launch vehicles. The materials are based on different types of epoxy matrices, bismaleimide matrix and PEEK. The temperature dependent anisotropic elastic constants and thermal expansion coefficients are experimentally obtained and used in the analytical predictions of delamination propagation and matrix crack onset. Static tensile tests revealed that the matrix cracks tend to take place at drastically lower mechanical load under cryogenic environment, posing the possibility of fuel leakage through the chain of these matrix cracks. Interlaminar fracture toughness measurement showed that the toughness tend to increase at cryogenic condition. Numerical predictions of delaminations and matrix cracks based on the simple energy release rate calculations are shown to be in good agreement with the experimental results.
Keywords cryogenic environment, liquid propellant tank, mechanical properties, tensile strength, fracture toughness, delamination, matrix crack, propellant leakage.

Theme : Industrial Applications ; Aerospace Applications

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