Dynamic coupling on the design of space structures

Resumen

For the design of space structures, the dynamic coupling between equipment and the satellite (or between a satellite and the launcher) is usually avoided due to negative effects like high stresses produced by structural resonance. The usual procedure to assure the dynamic decoupling is by limiting the minimum value of natural frequency of the secondary structure to a value high enough above the main natural frequencies of the main structure. However, in some spacecraft configurations, it is unavoidable that some parts or equipment present natural frequencies close to the main natural frequencies of the spacecraft because these parts may be massive or may have a special interface design with low stiffness. This dynamic coupling provokes modifications on the modal behavior of the satellite, which can lead to a significant decrease in the first natural frequency of the entire satellite. To analyze this phenomenon, a representative but simple mathematical model is studied to evaluate the influence of the design parameters of space structures. Analytical expressions are obtained that can help to highlight the influence of the parameters. The results are demonstrated with the example of the UPMSat-2 satellite design.