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PLATO - TOU Mechanical Design & Future Activities. Osservatorio Astronomico – Catania June 11 th , 2014. Overview. TOU Mechanical Design Overview Architecture Materials Future Activities L6 failure: Investigation & design improvement
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PLATO - TOUMechanical Design&Future Activities Osservatorio Astronomico – Catania June 11th, 2014
Overview • TOU Mechanical Design Overview • Architecture • Materials • Future Activities • L6 failure: Investigation & design improvement • Architecture consolidation: FPA interface, integration, baffle, … • Modelling activities (FEM & TMM) • Prototype lens mounts • Resources Availability
TOU Mechanical Design (1) The TOU consists of: • Structural tube • Machined AlBeMeT part (outstanding combination of properties) • Outside gold coated to minimize radiative coupling • Inside black coated to optimize straylight behavior • Thermal connection between FPA and baffle (which acts as radiator) • Lens mounts and interface parts • Multi-finger design to minimize bonding surface and provide isostaticity to the lenses • Materials choice to match the glasses CTE • Isostatic interface to tube to compensate for CTE mismatch • Isostatic mounts to the S/C optical bench • 3-points interface to allow alignment by shimming
Materials • Material choice drivers • Main Structure: combination of properties (, CTE, Cp, E) • Lens Mounts: Minimization of thermo-elastic stresses in the lenses (CTE, E)
L6 failure:Investigation & design improvement • During the DM campaign cracks were observed at the four bonded interfaces of L6. • The failure is reproducibele, therefore workmanship can be excluded. • The root cause nees to be identified. • A plausible hypotesis is an excessive bonding area, which leads to high thermo-elastic stresses in the glass. • The flexibility of the mount has to be verified • Breadboards will be used to prove the improvements implemented.
Architecture Consolidation The following points will be investigated to update and improve the design: • FPA interface • The last FPA developments were not considered. • Optics integration • Accessibility, fixation points of dedicated tooling, ... • Baffle interface • Requiements consolidation for the interface to the S/C OB. • Handling interfaces for integration at S/C level.
Modelling activities (FEM & TMM) • Currently, at UBE there is a strong team capable of performing mechanical and thermal modelling. • NASTRAN, ESARAD, SYSTEMA available. • Performing FEM and TMM at the same location allows a more efficient and fast optimization of the overall design. • Such activities will be included in our PRODEX proposal.
Prototyping • UBE is ready to support prototyping activities, e.g. lens mounts with improved design and/or alternative materials. • Small scale BB are, as well, foreseen to verify envisaged design improvements.
Short-Term Planning & Resurces • Due to the very high work loat at UBE it is not possible to allocate full time personnel to PLATO right now. • To support PDCR (mid March 2015) some resources will be made available. In particular FEM/TMM. • In the second quarter of 2015 experienced personnel will be available for PLATO.