The Tape Spring Hinge Deployment System of the EU:CROPIS Solar Panels

Abstract

Eu:CROPIS is a compact satellite featuring a biological. The cylindrical Satellite of 1m diameter has four deployable panels for power generation. Those panels are connected to the main structure by glassfiber reinforced polymer (GFRP) tape spring hinges. The hinges, comparable to curved metallic measuring tapes, have elastic energy stored when flattened and folded and thus deploy the panels by simply unfolding. When unfolded the hinges snap into their original shape and support the panels with considerable stiffness. No friction or mechanical locking is involved in the deploying process, which increases the systems reliability. Despite all these advantages other design aspects need special consideration. The GFRP needs to be protected against environmental influences like atomic oxygen and heat. Depending on the folded state and the hinge configuration the length of the hinges cannot be chosen freely. The installation process requires consideration as well. While the hinges are very flexible in the folded state they have to be installed quite accurately to be able to snap into their deployed position and fully support the panel. The panels do not deploy around one single axis but also do lateral movements. Even though the hinges are able to support the panels in the deployed position, they provide very low support during deployment. Therefore, gravity compensation is required for testing which should have a very low influence on the deployment. The presented paper gives an insight into the tape spring hinge deployment system of Eu:CROPIS. Design iterations are explained with the background of the decision making process influenced by the overall satellite configuration, tests and testability, experiences gained during integration and PA considerations. Further details of the manufacturing and integration process are described. The verification concept is outlined and explained. Tests performed for verification or gaining experience are described including the setup and considerations for the tests to be representative.