Multibody Analysis of solar array deployment using flexible bodies 

The present work of thesis was developed during a six month stage at EADS Astrium in Friedrichshafen, Germany.

The work, commissioned by the Structural&Thermal department and supervised by Dr. Bernhard Specht, consists in the creation of a flexible model of solar array structures.

The solar panels represent the main device to collect and convert solar energy into electrical energy and they are widely used in space missions to supply the energy necessary for both spacecrafts and payloads. To optimize the sun exposed surface the panels are usually organized in wings configurations, that, stored during the launch, deploy in the space at the beginning of the operative phase of the satellite.

This work of thesis focus on this deployment phase and on the associated dynamic loads. The need of this investigation is connected to the strict requirements on the deployment. Since we want  to be sure of the complete deployment in every condition with high margin of safety, the energy stored in the deployment mechanism is quite oversized. This leads to the dynamic loads that we want to estimate.

The key topic of the thesis consists in the generation of a flexible multi-body model for solar arrays deployment studies and analysis. The main aim of this model is the verification and validation of a usually pre-existing rigid model used for the conceptual studies of the deployment.

In this rigid model, generated directly in ADAMS environment, all the structural stiffness is condensed in a small number of DOF (rotational springs located on the hinge lines). It’s clear that this way of modelling does not cover higher frequency or side dynamics effects. By the introduction of a flexible model we want to investigate these effects and check the right working of the mechanism also in presence of deformation. Optionally, using the flexible model, we can also have a first estimation of stresses and strains due to the dynamics of the deployment.

The two main requirements for a flexible model are to be easy to generate and to be compatible with the related rigid model. These two aspects are important to avoid significant impact on the project budget. The flexible bodies are generated using the user friendly interface of PATRAN (avoiding or minimizing manual inputs in NASTRAN) and then importing this flexible bodies in an ADAMS adapted rigid  model (avoiding to re-built the flexible model from the beginning).

BEPI COLOMBO MPO and AMOS-3 solar arrays are used as applied examples for the model.