1. Luca Dassa – 02/03/2015 1 / 8 CRAB cavities meeting Bolt size (1) We are dealing with material where Yield strength and tensile strength are very close! We need to pay attention to the Safety Factor! Indian supplier: TorqBolt Inc.

2. Luca Dassa – 02/03/2015 2 / 8 CRAB cavities meeting Solution under analysisBolt size (2) Shear load for the bolts 1 V1 [N] 422 Shear load for the bolts 2 V2 [N] 422 Shear load for the bolts 3 V3 [N] 362 Normal load for the bolts 1 S1 without preload [N] 430 Normal load for the bolts 2 S2 without preload [N] 362 Normal load for the bolts 3 S3 without preload [N] 430 Normal load for the bolts 1 S1 with preload [N] 5784 Normal load for the bolts 2 S2 with preload [N] 5716 Normal load for the bolts 3 S3 with preload [N] 5784 Moment load for the bolts 1 due to V M1 [Nmm] 2111 Moment load for the bolts 2 due to V M2 [Nmm] 2111 Moment load for the bolts 3 due to V M3 [Nmm] 1811 Check preload for shear 1: OK if > 1 (at warm) 4.11 Check preload for shear 3: OK if > 1 (at warm) 4.06 Check preload for shear 3: OK if > 1 (at warm) 4.79 Max Shear load for the bolts [N] 422 Max Normal load with preload for the bolts [N] 5784 Max Moment load for the bolts due to V [Nmm] 2111 Shear stress for the bolts 1 τ1 [MPa] 26.2 Shear stress for the bolts 2 τ2 [MPa] 26.2 Shear stress for the bolts 3 τ3 [MPa] 22.5 Normal stress for the bolts 1 σ1 [MPa] 26.7 Normal stress for the bolts 2 σ2 [MPa] 22.5 Normal stress for the bolts 3 σ3 [MPa] 26.7 Bending stress for the bolts 1 σb1 [MPa] 199.6 Bending stress for the bolts 2 σb2 [MPa] 199.6 Bending stress for the bolts 3 σb3 [MPa] 171.3 Prestress σ0 [MPa] 332 Stress due to thermal contractio σth [MPa] 24.2 Combined stress σr1 [MPa] 585 Combined stress σr2 [MPa] 581 Combined stress σr3 [MPa] 556 Safety factor η1 1.42 Safety factor η2 1.43 Safety factor η3 1.49 Bolt Material Titanium gr. 5 Pitch p [mm] 1 Nominal diameter d [mm] 6 "Core" Bolt diameter d3 [mm] 4.7731 Outgassing hole diameter d [mm] 1.5 Bolt lenght L [mm] 10 Bolt length of the wolking thread Ld [mm] 9 Tensile stress area At [mm2] 16.13 Inertia of the Tensile stress area It [mm^4] 25.23 Corresponding bolt diameter in ANSYS d1 [mm] 4.53 Pretension constant K 0.4 Titanium gr 5 proof stress Sp [MPa] 830 Titanium gr. 5 Young's modulus E [MPa] 110000 Preload F [N] 5354 Pressure Pr [MPa] 0.18 Coefficient of static friction μ [-] 0.3

3. Luca Dassa – 02/03/2015 3 / 8 CRAB cavities meeting Bolt size (3) COMMENTS (2): We decrease the preload in order to not stress too much the bolts If the shear load is higher than the allowed one, we have a rigid body motion in the vessel between plates (stopped when the bolts touch the hole) If this happens, all the shear load is transferred on the weld seams COMMENTS (1): Previous analyses have been preformed with friction coefficient equal to 0.3 If I decrease the friction coefficient to 0.1, I need to increase the preload in order to have a SF(shear)=1.5 but I reduce the SF(bolts) COMMENTS (3) about Stainless steel bolts The huge stress due to differential thermal contraction decreases the SF(bolts). We need to further reduce the preload (down to 20%) in order to gain SF(bolts)=1.5 Stress due to thermal contractio σth [MPa] 284.7

4. Luca Dassa – 02/03/2015 4 / 8 CRAB cavities meeting Load cases QUESTION: When should I add the pre-tuning effect? Others QUESTION: Visit to Saclay (cryomodule assembly)?