Inverse Identification Method for the Dynamic Behavior of Nonstructural Elements on Spacecrafts Using Noncollocated Measures

Abstract

Abstract. Accurate prediction of vibrational dissipation in aerospace structures is essential for the design of these structures, which undergo extreme stresses during launches. These complex structures include a main load-bearing structure and various nonstructural elements that ensure the system’s proper functioning. Recent studies have revealed that nonstructural elements in spacecraft can significantly dampen the overall structure. This explains the differences observed between numerical models and experimental results for large amplitude vibrations. Vibrational energy dissipation is often modeled by modal damping, which does not represent the actual physical phenomena involved. Aerospace structures incorporate numerous nonstructural elements such as electrical harnesses, thermal protection, fluid lines, and various equipment. The mass of these elements, often representing 10–30% of the total mass of spacecraft, is significant. However, their dynamic behavior is not accounted for in global models, with only a distributed static mass being considered. In this article, to improve predictive models of aerospace structures, a specific identification method with noncollocated measures is necessary to develop a predictive dynamic model. The objective is to propose an inverse approach to identify the dynamic behavior of nonstructural elements based on a thorough understanding of the main structure and vibrational tests on the coupled structure. Experimental tests on the coupled structure, that is, the main structure with the nonstructural elements attached, are also conducted to establish an inverse identification method for the dynamic behavior of the nonstructural elements.