Uncharted Waters: Vibration Measurement in Thermal Chambers

Most space flight structures typically are tested for thermal and vacuum survivability, cycled initially at the component level to relieve internal strains and as an end product to verify thermal balance and operation as a complete system. Dynamic testing is generally performed on the individual components and as a complete system prior to the thermal vacuum test. This paper discusses a test requiring vibration data measurement in a thermal environment. Vibrations were induced internally by the thermal cycling of the structure (internal stress relief) as well as input with a shaker system capable of operating at cryogenic (LN2) temperatures. The intent of this vibration input was to characterize the structure rather than performing a qualification vibration environment. Requests for vibration measurements in thermal and vacuum environments are becoming more common, although this is the first test completed at Lockheed Martin Sunnyvale.