Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : November 02, 2019 - November 04, 2019
Composite cryogenic propellant tank technologies are promising approaches to reduce structural weight of rockets to improve their performance. However, the strength reduction of adhesive bonded joints used for Carbon Fiber Reinforced Plastic (CFRP) tank is considered as a critical issue when the joints are exposed to cryogenic environment. In this study, Finite Element (FE) analysis was carried out for CFRP-CFRP bonded joints as a fundamental research. In order to analyze the strength of them, strain energy release rate was calculated by Virtual Crack Closure Technique (VCCT), which includes temperature dependency of material properties obtained by tensile and thermophysical properties tests. Tensile tests were conducted for IMS60/#133 of CFRP and AF163-2K film adhesive at room and cryogenic temperature to obtain elastic moduli. Thermophysical properties tests were conducted for IMS60/#133, AF163-2K, and A6061-T6 at from -150℃ to 150℃ to obtain coefficient of thermal expansion. According to FE analysis, it was founded that plastic elongation decrease in adhesive at cryogenic temperature has a significant effect on energy release rate of CFRP-CFRP bonded joints compared with increase in elastic moduli and thermal shrink. Therefore, the results suggested that the strength reduction of adhesive joints might be caused by decrease of adhesive plasticity at cryogenic temperature.
