Free vibrations of ultrathin deployable booms fabricated with nano-modified epoxy matrix

Ultrathin deployable boom structures are investigated to increase the mission capacity of small spacecrafts within their limited package volume. The successful integration of boom technology would allow small satellites to perform missions that are commonly reserved for larger and more complex space platforms. The boom is directly exposed to the space environments, which produces detrimental effects of the overall properties of the composite structure. On the other hand, the dynamic characterization of boom structures during the deployment phase and in deployed configuration is of primary importance to understand the factors that influence the operative behavior of the entire satellite. Polymer-based composites are a class of materials that have gained more attention for damping applications. The introduction of nanoparticles to the polymer matrix can add large benefits. Recent studies showed that nanocomposites possess a high potential for damping applications. In addition, certain nanoparticles, such as nanosilica, can enhance the resistance of composite materials to the space environments. In this work, we aim to investigate the effects of nanoparticles on the free vibrations of boom structures. In the first part of this work, we fabricated prototypes of 1 m-long self-deployable ultrathin booms with V cross-section geometry using 1K carbon fiber reinforcement and epoxy resin modified with nanoparticles. In particular, we used nanosilica and graphene oxide at 1 wt% and 2 wt%. The manufacturing process was studied and optimized in order to fabricate reproducible and reliable structures. Then, in order to investigate the effects of the nanoparticles on the vibrational response of the nanocomposite booms, we performed modal testing by impulsive excitation method. Natural frequencies and modal shapes were determined for each nanocomposite boom and compared with those of the equivalent fiber reinforced composite boom with unmodified epoxy resin. Further, natural frequency analysis of the boom structures was performed by finite element method (FEM) in order to deep understand the role of nanoparticles on dynamic behavior. A multiscale approach was used to determine the mechanical properties of nano-modified epoxy matrix and those of the lamina. These data were applied as input for the structural analysis.