Challenges in Simulating the Forced Vibration Response of Assembled Space Structures

This chapter presents an example of how challenging can be the validation of system responses when a product must be certified before being commissioned for a launch or flight. Several divisions of industry dealing with dynamic models and simulations of forced vibrations are discovering how the nonlinear dynamics of joints can lead to inaccuracies in the simulated vibration responses, mainly due to the nonlinear relationships of frequency and damping with the vibration amplitude (which is high for qualification tests). Hence, the example of this chapter refers to analysis of test data gathered from a solar array in qualification tests. It is shown how dissimilar simulated and measured vibration data can be, and how the qualification levels enhance the nonlinear dynamics, often not predicted by dynamic models. Finally, it presents an effort to analyse a cut-out of the solar array in terms of frequency and damping nonlinearity.