Study on Ground Verification for Large Deployable Modular Structures

A quantitative assessment is provided of the difficulty of ground deployment tests and evaluates the validity of modularized deployment testing for large space structures. An index that well shows the difficulty of ground deployment tests is the ratio of gravity force to deployment force. The relationship between this index and the accuracy of deployment tests is calculated using an analysis model of the large deployable antenna reflectors onboard Engineering Test Satellite VIII (ETS-VIII). The index showed that a deployment structure whose diameter is more than 10 m has insufficient evaluation accuracy; thus the structure should be divided into modules. The index also showed that the single module of the large deployable antenna onboard ETS-VIII is of the appropriate size to evaluate deployment reliability. The influence of module connection on the deployment motion is also examined. The cross correlation between the changes in strain energy profile during deployment in a single module and those in combined modules is calculated to show how many modules should be connected and tested. The resistance force that arose due to the module connection is also calculated using the beam strain energy. It is clarified that ground deployment testing for four combined modules should be conducted in addition to the ground deployment testing for a single module when the deployment force margin is not large enough.