Using vibration-based monitoring to detect mass changes in satellites

Vibration-based structural health monitoring could be a useful form of determining the health and safety of space structures. A particular concern is the possibility of a foreign object that attaches itself to a satellite in orbit for adverse reasons. A frequency response analysis was used to determine the changes in mass and moment of inertia of the space structure based on a change in the natural frequencies of the structure or components of the structure. Feasibility studies were first conducted on a 7 in x 19 in aluminum plate with various boundary conditions, which was impacted with a mallet and the frequency response was determined. The frequency response for the blank plate was used as the basis for detection of the addition, and possibly the location, of added masses on the plate. Statistical variation of the data was determined to allow variations of frequency due to added mass and thermal changes to be evaluated. Effect on damping was also investigated. The test results were compared to both analytical solutions and finite element models created in SAP2000. The testing was subsequently expanded to aluminum alloy satellite panels and a mock satellite with dummy payloads to determine the thresholds of detectability.Air Force Research Laboratory Space Vehicles DirectorateCivil EngineeringMastersUniversity of New Mexico. Dept. of Civil EngineeringMaji, ArupTaha, MahmoudNg, Perc