1. Daniele Piazza PLATO TOU Meeting, Catania, 11.06.2014 PLATO - TOU Mechanical Design & Future Activities Osservatorio Astronomico – Catania June 11 th, 2014

2. Daniele Piazza PLATO TOU Meeting, Catania, 11.06.2014 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

3. Daniele Piazza PLATO TOU Meeting, Catania, 11.06.2014 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 TOU Mechanical Design (1)

4. Daniele Piazza PLATO TOU Meeting, Catania, 11.06.2014 TOU Mechanical Design (2)

5. Daniele Piazza PLATO TOU Meeting, Catania, 11.06.2014 Materials  Material choice drivers  Main Structure: combination of properties (, CTE, Cp, E)  Lens Mounts: Minimization of thermo-elastic stresses in the lenses (CTE, E)

6. Daniele Piazza PLATO TOU Meeting, Catania, 11.06.2014 Future Activities

7. Daniele Piazza PLATO TOU Meeting, Catania, 11.06.2014  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. L6 failure: Investigation & design improvement

8. Daniele Piazza PLATO TOU Meeting, Catania, 11.06.2014 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. Architecture Consolidation

9. Daniele Piazza PLATO TOU Meeting, Catania, 11.06.2014  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. Modelling activities (FEM & TMM)

10. Daniele Piazza PLATO TOU Meeting, Catania, 11.06.2014  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. Prototyping

11. Daniele Piazza PLATO TOU Meeting, Catania, 11.06.2014  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. Short-Term Planning & Resurces