國際太空站專用電腦之結構分析與設計改良

Abstract

本論文針對將放置於國際太空站美國艙中的太空電腦ACOP之結構進行分析，ACOP太空電腦設置的主要任務是替反物質磁譜儀國際合作計畫蒐集並傳送實驗數據。太空電腦的結構設計須符合NASA給予的設計規範，再依標準流程建立有限單元模型，最後以NASA認可的軟體進行分析。不同於一般在地球上使用的電腦，太空電腦需經歷嚴苛的升空、降落等運送過程，因此電腦的結構強度特別重要。進行分析時，除了考慮升空帶來的穩定加速度負載，還需計算太空梭艙體隨機振動與電腦結構自然頻率交互作用的影響。本論文針對ACOP太空電腦初始結構設計進行改良，從了解系統的主要振動模態以及產生振動的元件，以改變系統自然頻率的觀點，變更系統結構設計，避免系統主要自然振頻落在太空梭振動能量較大的範圍，同時減少系統內部元件之間的共振，降低振動給予結構的負載，有效達到改良太空電腦結構設計的目的。

In this thesis, the structure of a space computer (ACOP, AMS-02 Crews Operation Post) was designed and analyzed. This computer will be placed in the U.S. Laboratory in the International Space Station. The major mission of ACOP is to store and transmit experimental data collected by an anti-matter spectrometer (AMS) set up by an international collaborating project. The structural design of ACOP has to follow the standard and design rules regulated by NASA. A finite element model is built to verify the structural safety of ACOP. The methodology and software used in the structural analysis should be approved by NASA. Different from computers used on the earth’s surface, ACOP will experience severe environmental conditions during the stage of liftoff and landing. Therefore, the structural strength of the ACOP is particularly important. The ACOP structure should be designed to maintain positive margin of safety during liftoff and landing acceleration and random vibration conditions, and the nature frequency of ACOP structure shall comply with requirement defined by NASA. This thesis focuses on the structural modification of the preliminary ACOP computer design. In order to reduce the vibration loading on the ACOP structure, it is necessary to prevent the major natural frequencies fall within the region that the crate of ACOP has larger vibration energy, as well as reduce the resonance of those internal parts and elements of the ACOP system. By analyzing the structural vibration modes of the original system and the parts that cause vibration, the system structure is redesigned to alter the natural frequency to reduce the vibration loading. Structural strength is effectively improved using the fore-mentioned approach.