• Journal of the Korean Society for Nondestructive Testing
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• v.15 no.4
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• pp.549-560
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• 1996

The purpose of this study is to investigate the usefulness of small punch(SP) test using miniaturized specimens as a method for fracture strength evaluation of CANDU pressure tube embrittled by hydrogen. According to the test results, the fracture strength evaluation as a function of hydrogen concentration at $-196^{\circ}C$ was much better than that at room temperature, as the difference of SP fracture energy(Esp) with hydrogen concentration was more significant at $-196^{\circ}C$ than at room temperature for the hydrogen concentration up to 300ppm-H. It was also observed that the peak of average AE energy, the cumulative average AE energy and the cumulative average AE energy per equivalent fracture, strain increased with the increase of hydrogen concentration. From the results of load-displacement behaviors, Esp behaviors, macro- and micro-SEM fractographs and AE test it has been concluded that the SP test method using miniaturized specimen($10mm{\times}10mm{\times}0.5mm$) will be a useful test method to evaluate the fracture strength for CANDU pressure tube embrittled by hydrogen.

• Composites Research
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• v.37 no.3
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• pp.219-225
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• 2024

It is essential to develop a light-weight, high-performance structure for the deployable reflector antenna, which is the payload of a reconnaissance satellite, considering launch and orbital operation performance. Among them, the composite main reflector is a key component that constitutes a deployable reflector antenna. In particular, the development of a high-performance main reflector is required to acquire high-quality satellite images after agile attitude control maneuvers during satellite missions. To develop main reflector, the initial design of the main reflector was confirmed considering the structural performance according to the laminate stacking design and material properties of the composite main reflector that constitutes the deployable reflector antenna. Based on the initial design, four types of composite main reflectors were manufactured with the variable for manufacturing process. As variables for manufacturing process, the curing process of the composite structure, the application of adhesive film between the carbon fiber composite sheet and the honeycomb core, and the venting path inside the sandwich composite were selected. After manufacture main reflector, weight measurement, non-destructive testing(NDT), surface error measurement, and modal test were performed on the four types of main reflectors produced. By selecting a manufacturing process that does not apply adhesive film and includes venting path, for a composite main reflector with light weight and structural performance, we developed and verified a main reflector that can be applied to the SAR(Synthetic Aperture Rader) satellite.