後藤 健

This study investigated cumulative damage mechanisms of short fiber type C/SiC under compression. To measure mechanical properties (unloading modulus and permanent strain) before fracture, repeated loading-unloading tests were conducted using a strain gage. Damage was observed to assess characteristics of crack density, length, number, and propagation angle. Furthermore, relations between mechanical properties and damage characteristics were elucidated by application of Basista's equations and by substituting crack densities inferred from damage observations. Stress-strain relations revealed nonlinear behavior. The unloading modulus did not change, but the permanent strain increased. Cracks propagated mainly between fibers, without fiber fracture, connecting other cracks in the direction of orientation 0 deg to 30 deg to the compressive axis. We estimated permanent strain using Basista's equations and damage characteristics. Estimates roughly agreed with experiment results, suggesting that the permanent strain increase is attributable to closed crack sliding and friction caused by increased crack density.

We present an overview of the cryogenic system of the next-generation infrared observatory mission SPICA. One of the most critical requirements for the SPICA mission is to cool the whole science equipment, including the 2.5 m telescope, to below 8 K to reduce the thermal background and enable unprecedented sensitivity in the mid- and far-infrared region. Another requirement is to cool focal plane instruments to achieve superior sensitivity. We adopt the combination of effective radiative cooling and mechanical cryocoolers to accomplish the thermal requirements for SPICA. The radiative cooling system, which consists of a series of radiative shields, is designed to accommodate the telescope in the vertical configuration. We present thermal model analysis results that comply with the requirements to cool the telescope and focal plane instruments.

© CCM 2020 - 18th European Conference on Composite Materials. All rights reserved. In molding of carbon fiber reinforced thermoplastics (CFRTP), resin impregnation behavior to fiber yarns is very important because higher viscosity of molten thermoplastics inhibits resin impregnation to the interspace among fibers. Resultant resin un-impregnation causes lower mechanical properties of CFRTP. The purpose of this study was to clarify the relation among molding method, molding conditions and resin impregnation to fiber bundles experimentally. In this study, CFRTPs using continuous carbon fiber yarn as a reinforcement and a thermoplastic polyimide which is excellent in heat resistance as a matrix resin were produced by Micro-Braiding, Film Stacking and Powder method. As a result, as the molding time increased, the impregnation ratio increased. The resin impregnation saturated in a certain molding time and the time was shorter the larger molding pressure. In addition, as the resin impregnation ratio increased, the mechanical properties also tended to increase.