The connector for extravehicular operation by astronauts is a key component for repairing devices in the space station. The paper studies mechanism of the vacuum cold welding phenomenon of the connector, analyzes its threats to the connector, provides appropriate measures for preventing vacuum cold welding and verifies these measures through experiment. The results indicate that the connector does not occur vacuum cold welding phenomenon during the experiment and the above measures are effective. Therefore, the study is important and significant for ensuring the long-term and reliable operation of the connector in the space station.
The paper selects 22# locating detent in the JYH extravehicular connector as the research object, builds a force model for locating detent in the connector, and conducts force analysis for shortening problem due to locating detent. Through conducting force calculation and ANSYS simulation for clamping the jaw of the locating detent, the paper provides the failure mechanism of the locating detent under overload. Besides, the paper prepares a failure test for locating detent under overload and deploys the test. By analyzing deformation quantity and microscopic fracture morphology of locating detent, the paper verifies the failure mechanism and determines the validity of the failure mode of locating detent under overload.
Based on the application requirements of the complex border defense and coastal defense, an intelligent photoelectric detection and identification system is proposed. This paper introduced its main components and working strategy. The system adopts dual band detection of visible and infrared light to realize all-weather detection of specific regions, and uses the intelligent identification technology of image features to implement the accurate identification of specific targets. The integrated communication mode of ground-based 4G communication and low earth orbit satellite communication is selected to quickly upload the compressed detection information, to ensure the stability and continuity of communication in various environments. The system is expected to exert an important effect on target detection and identification in the field of border and coastal defense in the future.
Aiming at the problem of fiber break failure of optical fiber connector used in aerospace wide temperature range environment, the finite element simulation model is established based on the mature optical fiber contact structure. The influence of some typical factors, such as expansion coefficient of fiber adhesive, filling amount of adhesive, and material of metal tailstock, on the internal stress of optical fiber contact parts is analyzed quantitatively at extreme temperature of +100℃ and -100℃. It is found that the axial force exerted on the fiber by the metal tailstock and ceramic ferrule due to high and low temperature expansion and contraction is the main source of the internal stress. The junction area of ceramic ferrule cone and straight section is the most prone to fiber breakage. The difference between the maximum axial internal stress of optical fiber at +100℃ and -100℃ is regarded as the index to evaluate the internal stress of optical fiber. The metal tailstock with low expansion coefficient can significantly reduce the internal stress of optical fiber. Compared with aluminum alloy tailstock, the maximum stress difference of Kovar alloy tailstock can be reduced by 51.5%. The internal stress of optical fiber can be reduced to a certain extent by appropriately reducing the filling amount of optical fiber adhesive between ceramic core and metal tailstock and the expansion coefficient of optical fiber adhesive. The results show that the maximum stress difference can be reduced by 11.4% if only the conical region is filled. When the thermal expansion coefficient of optical fiber adhesive decreases from 60e-6/℃ to 30e-6/℃, the maximum stress difference declines by 8.9%. This paper can provide a reference for improving the design of optical fiber connector for aerospace wide temperature range.
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