Guglielmo S. Aglietti

Well-integrated systems and structures can increase reliability and decrease structural complexity for deployable spacecraft structures. This study investigated the feasibility of a self-deployable space baffle design inspired by the spiral structure of a volute spring. The principles of storing and releasing elastic potential energy within a volute spring were applied to the new baffle design, referred to as the volute baffle. The extension system was integrated with the deployable baffle surfaces to reduce the number of parts, thereby reducing the risk of deployment failure in harsh space environments. A set of derived analytical equations and finite element analysis (FEA) models were used to investigate the mechanical properties of the volute baffle. The linear region of the volute baffle can be accurately modeled by both the FEA and analytical model. The analytical model captured nonlinear behavior slightly better than the FEA solution. A hard stop on extension length was integrated into the spiral structure of the volute baffle, making it more resilient to disturbance and increasing the accuracy of deployed length. Concerns related to static friction, vibration, material choice, and manufacturability were addressed to ensure successful deployments. No deployment failures were observed in the function prototype, which was designed and manufactured with the implemented design features.

The launch mechanical environment presents a multi-axis random vibration excitation to the launch vehicles and spacecraft payloads. However, ground vibration testing of these systems abides by sequential, single-axis inputs, enveloping flight vibration levels along individual axes. The actual vibration direction depends on the excited mode shapes, and in general it is not precisely aligned with any given reference axis of the article. The response acceleration could be in any direction, with strong local variations expected, depending on both the properties of the structure of interest and the applied loads. In this paper, it is first shown that matching all response acceleration components due to a realistic environment by single-axis testing is, in general, impossible. Subsequently, minimum amplification factors for single axis to match realistic reference environments are quantified, such that both acceleration responses and elemental stresses were covered for the whole spacecraft in at least one of the uniaxial tests. This procedure was repeated for five different realistic spacecraft models. It was found that a consistent amplification factor and, respectively, overtesting, were necessary for the single-axis excitation sequence to properly validate the articles’ survivability against the true mechanical launch loads.