Creation of a Finite Element Model andSystem Analysis for the Low and HighFrequency Cryogenic Telescopes of theSpace Mission LiteBIRD

Abstract: The Lite (Light) satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection (LiteBIRD) is a Japan Aerospace Exploration Agency (JAXA)-led Strategic Large-Class mission designed to search for the existence of the primordial gravitational waves produced during the inflationary phase of the early Universe, through the measurement of their imprint onto the polarization of the Cosmic Microwave Background (CMB). It is an international collaboration, with European Union (EU) operations being coordinated by France. A short study on the merits of 2-dimensional versus 3-dimensional elements in the Finite Element Model (FEM) meshing of basic plates and beams was performed as well as the analysis of two different methods of representing threaded connections in FEM models. Both these activities were in service of the creation of a FEM model of the structure of the contribution of the EU to LiteBIRD: the Medium-High-Frequency Telescope (MHFT). All analysis was done using the Siemens NX software and the Simcenter Nastran solver. This model has passed preliminary quality checks and will be used for future structural analysis intended to verify the integrity of the design, its compliance with JAXA requirements, and to perform screw dimensioning. The results of those analyses will inform possible future design changes or will support the current design. Logistical work on the project was also performed, consisting of the groundwork to initiate an Assembly, Integration and Testing (AIT) plan and an Assembly, Integration and Verification (AIV) plan. This primarily involved the creation of a Model Definition Document, which contained clear and complete descriptions of the different MHFT models to be used throughout project development. The document defines the purpose and components of the models, the dependencies between models, as well as the necessary tests to be performed on each as part of the AIT and AIV process. A list of the structure interfaces was also created, which will contribute to the development of an interface control document.