Durability of Quick Reaction Satellite Antenna (QRSA) Trunnion Castings.

摘要

Repeated failures of quick reaction satellite antenna (QRSA) trunnion castings in the field caused alarming concerns about their durability. Arguments over the cause of the failures, ranging from improper installation, unbalanced and/or excess force to poor design and insufficient material strength, have been disputed between the contractor and the government engineers. Incipient melting during solution treatment was also suspected as one of the reasons responsible for cracking in the original aluminum castings. This study compared the microstructures of as-cast and heat-treated samples and concluded that incipient melting did not occur during solution treatment and thus was not the principal cause for cracking in the aluminum castings. Eventually, the light aluminum alloy was replaced by a heavier but stronger ductile iron. As a result, the durability of the QRSA trunnion casting has been significantly improved and the deficiency was remedied.... Trunnion casting, QRSA, Failure analysis, Aluminum alloy, Ductile iron, Durability.