ATLAS ITk Upgrade: SLIM Update Diego Álvarez Feito PH-DT Engineering Office, CERN CERN, January 2015 20/01/2015

SLIM Stave: Mechanical Analysis Mechanical/deformation analysis of two ‘longeron’ design concepts Mass optimisation started by S. Michal Six ribs (0.3mm thick) connecting the longerons Module cells & barrel section assumed not to play structural role “Open” Longerons Longerons with “stiffening box” 20/01/2015

SLIM Stave: Open Longeron “Open” Longerons Sandwich construction for longerons 0.2mm thick CFRP longerons (Quasi-isotropic 67µm ply, [-60,0,60]) 1.5mm thick core (PVC foam, 80kg/m3) CFRP Ribs (Quasi-isotropic 67µm ply, [-45,0,45,90]) Cells modelled as forces (applied to bolt holes) Tilted Cells: 8.99g each Barrel Cells: 36.4g each Quasi-kinematic supports at the ends of the cooling lines Layered shells Solid elements Layered shells Unidirectional K13D has been assumed in all the simulations to see the lower limit of the deformation. However, alternatives such as M55J or M50J will be investigated next. Woven plies could also be considered next to meet specific thickness requirements. 20/01/2015

Open Longeron: Results Total mass: 525g Max. deformation (Gravity) ≈ 192µm 20/01/2015

Open Longeron + Central Covers: Results Top and bottom covers for increased stiffness 0.2mm thick CFRP (Quasi-isotropic 67µm ply, [-60,0,60]) Bonded to longerons and first two ribs Total mass: 548g Max. deformation (Gravity) ≈ 154µm 20/01/2015

SLIM Stave: Longeron + Stiffening Box Sandwich section 0.3mm skins (67µm ply, [-45,0,45,90]) 1.5mm thick core (PVC foam, 80kg/m3) Stiffening box 0.3mm skins (67µm ply, [-45,0,45,90]) 2mm thick top core (PVC foam, 80kg/m3) Longerons with “stiffening box” CFRP skins: Layered shells Solid bodies: Solid elements CFRP Ribs (Quasi-isotropic 67µm ply, [-45,0,45,90]) Cells modelled as forces (applied to bolt holes) Tilted Cells: 8.99g each Barrel Cells: 36.4g each Quasi-kinematic supports at the ends of the cooling lines Unidirectional K13D has been assumed in all the simulations to see the lower limit of the deformation. However, alternatives such as M55J or M50J will be investigated next. Woven plies could also be considered next to meet specific thickness requirements. 20/01/2015

Longeron with SBox: Results Total mass: 586g Max. deformation (Gravity) ≈ 153µm 20/01/2015

Longeron + Reinforced SBox Core at the top of stiffening box made out of QI T300 for increased inertia Total mass: 633g Max. deformation (Gravity) ≈ 95µm 20/01/2015

Future Work Material optimisation Alternative materials (e.g. M55J, M50J, M46J) Optimised layups and skin thickness Structural analysis/integrity of tilted cells 20/01/2015