SPIRET: An Innovative Technique for Random Vibration Testing Of Large Spacecraft

Abstract System Point Input Random Excitation Testing (SPIRET) was developed as an alternative to both system level acoustics and base-shake random vibration testing of large spacecraft. The goal of SPIRET was to obtain an enhanced workmanship test of the spacecraft, prior to launch, by inducing a higher, more uniform dynamic acceleration response throughout the integrated system. The underlying SPIRET concept is to utilize the spacecraft modal characteristics to amplify the shaker input force and produce a high acceleration response throughout the flexible structure. SPIRET utilized commercial off-the-shelf vibration equipment coupled with satellite specific Mechanical Aerospace Ground Equipment (MAGE). Random vibration control was achieved using inline load cells and a Force Spectral Density (FSD) input spectrum which effectively provided both feedback control of the shaker and force limiting during the vibration test. SPIRET effectiveness was verified using a hi-fidelity spacecraft simulator which was ...