Dynamic Response Analysis of a Nanosatellite in Time and Frequency Domain due to the Seperation

An analytical procedure is developed for evaluating response of a shock loaded structure at some points of a nanosatellite having no need to complete simulation. This procedure sounds to be useful because of nature of the shock and complexity of the model that entails a very time consuming and convoluted finite element analysis. The given nanosatellite comprises shock-sensitive subassemblies subjected to pyroshock loads due to satellite separation from launch vehicle. As pyroshocks are most often synthesized from its response spectrum, an acceleration time history is first synthesized. The transmitted shock level to subsystems is determined in both time and frequency domains. In the time domain, the response of the subsystems or any perceived point is obtained by means of the acceleration-time history as well as a simplified model of limited DOFs. In the frequency domain, a maximum probable response might be predicted in each subsystem, employing response spectrum of the exerted shock together with multiple-DOF modal matrix. Finally, validity of the procedure is assessed by means of comparison of the maximum response in the time domain with the maximum probable response of the pyroshock spectrum in the frequency domain. Theoretically, result of SRS cannot accurately assign the response that, however, is used to get an immediate realization of dynamic behaviour of the system. So non conformity of responses has been prospected from the beginning and, consequently, verification is based on whether results of analysis in the frequency domain cover the ones in the time domain.