University of Patras School of Engineering Mechanical Engineering & Aeronautics Department Applied Mechanics and Vibrations Laboratory Ph.D. Dissertation Design, Analysis and Optimization of a Micro-Satellite for the Study of Lower Thermosphere and Re-Entry conditions Andreas G. Ampatzoglou Dipl. Ing. Mechanical & Aeronautics Patras, 2017 Page 1 Ph.D. Dissertation Andreas G. Ampatzoglou This page has been left blank intentionally Page 1 Ph.D. Dissertation Andreas G. Ampatzoglou This thesis is dedicated to my father Sky is not the limit, when there are footprints on the moon! Paul Brandt Page 2 Ph.D. Dissertation Andreas G. Ampatzoglou This page has been left blank intentionally Page 3 Ph.D. Dissertation Andreas G. Ampatzoglou Examination Committee 1. Professor Vassilis Kostopoulos (Thesis supervisor) Mechanical Engineering and Aeronautics Department, University of Patras, Greece 2. Professor Dimosthenis Polyzos (Thesis advisor) Mechanical Engineering and Aeronautics Department, University of Patras, Greece 3. Professor Nick Anifantis (Thesis advisor) Mechanical Engineering and Aeronautics Department, University of Patras, Greece 4. Professor Antonis Tsourdos School of Aerospace, Transport and Manufacturing, Cranfield University, UK 5. Professor Theodoros Loutas Mechanical Engineering and Aeronautics Department, University of Patras, Greece 6. Professor Antonis Tzes Electrical and Computer Engineering Department, University of Patras, Greece 7. Professor Ioannis Daglis Physics Department, National and Kapodistrian University of Athens, Greece Page 4 Ph.D. Dissertation Andreas G. Ampatzoglou Page 5 Ph.D. Dissertation Andreas G. Ampatzoglou Acknowledgements As this thesis is a collection of works of a collection of people contributing to this final manuscript, I would like to talk a little about all these different people and their role in making this possible. First, I would like to express my gratitude to Prof. Vassilis Kostopoulos for offering me the chance to pursuit my dreams and my passion. The resources along with the freedom and open-mindedness he provided me all these years, made this thesis concluded successfully. His advices and the continuous academic/scientific guidance shaped me as a researcher and helped me through this long and difficult route. Through these years, some people played a distinct role in my personal/academic life, so I would like to thank them in particular; Panos (you know who you are!) many thanks for the tireless support, our weird transfers, your sweet irony and your company in the smoking area (I know mate, you don’t smoke!). Christina K., many thanks for your continuous support, psycho-therapies and the discussions (mainly from your side!) that helped me a lot throughout the years. Dimitrios “the uncle” Mazarakos thank you for making my everyday life in lab simpler and more tolerable and for the significant academic guidance whenever asked. Making it through a 7-years period and coming to the finish line, wouldn’t be possible without the help and support from the entire AML community. So many thanks to all you people: Nikos A., Thanos, Kotzak, Antonis, Teo, George S. (many thanks for the T-VAC chamber!), Nasos (aka the pharmacist!), Thodoris “the old man”, Stavros, Nastos, Dimitris (my buddy ♥), Christoforos, Nikos S., jimmie_keei, Sofia, MJ, Katerina, and anyone else I might have missed! Special thanks go to the people that may not have been close (geographically!) all these years, but a short phone call, a simple talk and a beer (or three…) with them always kept me sane. Filippos, Mitsos-Eugenia-Aggeliki, Vlachos, Nasa and the rest gang from hometown thank you very much. An exceptional “thank you” should be also stated to Konstadina (aka Little B.), for her priceless support, her patience throughout the numerous rehearsals and her understanding during the difficult last months of the thesis conclusion. A group of people that deserves special reference is the hackerspace family. Pierros “the Conan”, Manthos, Agis, Nanimo, Mashua, Aris, Elkos and all the guys of the hackerspace community, thank you very much for introducing me in the open source world and its principles and the perfect cooperation during the most difficult stages of the project; without you the UPSat project would still be a dream. Finally, Giannis K. (the beach guy!), Manos T. and G. Koveos are the people worked on this project from day one, so I want to thank you guys for all these years that you actually believed in this idea. Still, nothing would be possible without the education, the principles, the support (of any kind!) and the unconditional care provided by my family. George, Froso and Dimitris thank you very much for everything you gave me and all the tools you armed me with, for this long trip, that still goes on. I will always be grateful! Andreas G. Ampatzoglou Patras, April 2017 Page 6 Ph.D. Dissertation Andreas G. Ampatzoglou This page has been left blank intentionally Page 7 Ph.D. Dissertation Andreas G. Ampatzoglou Executive Summary - ΕΝ The scope of this thesis is to design, built and test a Double-Unit nanosatellite, with the view of launching and operate it in the lower thermosphere. The key innovative approach is the design optimization for an actual space mission, creating a hybrid design for the structural subsystem. The new design approach based on both aluminum and composite materials for the structural frame, fulfilling all design and test requirements and successfully delivered and set into orbit, proving the feasibility of the new design. Initially, the potentiality of building full composite CubeSat structures was explored. Two different designs were created, that met all design requirements and manufactured, using the vacuum bag- autoclave methodology (carbon-epoxy prepreg). Both structures were tested verifying the FEA results and the mass reduction between the new designs and the commercial available structure (CubeSat-kit) was close to 40%. Despite that, these designs proven not feasible, for use in an actual space mission, as no consideration was made for the internal subsystems. The design optimization, driven by mass-stiffness principles, led to a new “hybrid” design that met all system requirements, considering all the necessary subsystems of a CubeSat mission. Through Finite Element Analysis the feasibility of the new design was proved and this way it could be used in a space mission concerning a Triple-Unit CubeSat having onboard a deorbiting device (FP7-DeorbitSAIL). The author dealt with the design, analysis and manufacturing of the entire structural subsystem of the mission (electronics bus, 3U CFRP panels, and several small parts) following the aforementioned design approach. All structural components were manufactured using a space approved Cyanate-Ester/Carbon prepreg and autoclave methodology and met all design tolerances and mass requirements. The structural system was passed all required tests, withstood the launch loads and set into orbit fulfilling its mission. This way, the first attempt of delivering a flight model (subsystem level) is considered successful as the entire system (and thus the structural subsystem) was labeled as flight proven. The next step was the designing of a complete space mission (UPSat) from scratch, delivering a fully assembled, fully tested and fully functional Double-Unit CubeSat, under the framework of the FP7- QB50 project. The same design principles as before were followed concerning the structural sub-system, creating from scratch a “hybrid” design using both aluminum alloy and composite materials; the same composite material and lamination was also used for this chassis. The design was based on the use of composite materials as primary structural components, for mass reduction and enhancement of the structural integrity of the entire system and also the ease of access during the assembly and integration procedure. The design of all different subsystems and the assembly management in order to fulfill all design requirements, was one the major difficulties, during the Critical Design Review. Although, the fully assembled CAD model, and the FEA results from the required loading scenarios (Resonance, Quasi-Static, Sine and PSD vibrations, Thermal) passed successfully the CDR phase as the structural integrity and normal operation of all designed subsystems verified. The entire manufacturing, assembly and integration process took place in Greece and the systems engineering principles applied were in line with the ECSS standards. The author had major involvement Page 8 Ph.D. Dissertation Andreas G. Ampatzoglou and key role during this procedure; assembly and integration sequence, harnessing plan, test sequence etc. The in-house manufactured components met all design requirements, the system assembly performed inside a relatively clean environment, built in-house and all PCBs designed and built according to ECSS recommendations (NO involvement for the author during the PCBs manufacturing and software writing). The assembled system withstood all required tests, simulating the launch and operational environments verifying the FEA results for an adequately robust CubeSat system. All tests during the vibration campaign (HAI facilities) did not reveal any malfunctions in subsystem level while only visual inspection was performed for verifying the perfect condition of the external components. On the other hand, for the needs of the Thermal Vacuum Campaign, an in-house (AML/UPAT) TVAC chamber designed and manufactured and both tests (thermal cycling and