Modular Coil Assembly Bolted Joint PDR 2/22/07

Objectives The review objectives include... Define the location of additional inboard bolts Finalize the material selection and design of the shim and washers Establish the minimum bolt preloads for both types of joint Establish the adequacy of the bolted joint design through analysis consistent with NCSX Structural and Cryogenic Design Criteria and the NCSX Handbook for Bolted Joint Design Document the envisioned assembly sequence and assembly requirements

Three-Coil Assembly A-A A-B B-C C-C

Interface A-B 25 tapped holes, most on Type-A 1 through hole Type-A Type-B

Interface B-C 29 tapped holes, most on Type-B Type-B Type-C

Interface A-A 20 tapped holes

Interface C-C 24 through holes 8 tapped holes

A1 is special

A1 Welded Adaptor w/ Tapped Hole A-A 4 plcs A-B 2 plcs A-B 3 plcs

Inventory of Tapped/Through Holes

Tapped Hole

Through Hole

Assembly Requirements Position the coils accurately Minimize gaps

Assembly Sequence 1- Position coils and measure shim 2- Fabricate and install shim insulating bushing insulating layer

Assembly Sequence (2) 3- Position coils and measure bushing 4- Fabricate and install bushing Insulating washer

Assembly Sequence (3) 5- Install ½ in. thk load washer 6- Install spherical washers & nut

Bolt Tightening (1) CAD model layout of wrenches has been performed Options include low-profile torque wrench, supernut, hydraulic tensioner Hole catalog being developed by visual inspection, template checking Table A-B based on CAD layout low profile torque wrench

Bolt Tightening (2) Table B-C based on CAD Layout Supernut Dw=2.5-in D= 2.46-in L=1.93-in T= 1.75-in A286 (4340 is std)

Bolt Tightening (3) Table C-C based on CAD layout

Bolt Tightening (4) Table A-A based on CAD layout

Bolt Tightening (5) Layout of hydraulic tensioner is in progress 4.6 DIA 4.9

Bolted Joint Parameters (1) MATERIALS-

Bolted Joint Parameters (2)

Bolt Preload Nominal preload of 75-kips based on 85% of A286 yield strength Cool-down relaxation is -4% with Inconel load washer, +2% with Titanium Preload uncertainty for hydraulically tensioned studs w/ ultrasonic inspection

Joint Stiffness joint separates at 90-kip min preload

Maximum Shear Load Local model analyzed for 25-kips shear Max bushing stress is 67.4-ksi Compare to bushing material: Compressive strength = 60-ksi Min bearing strength = 30-ksi Max shear load = ~11-kip Local FEA model Through hole Tapped hole

Global Analysis w/ Bonded Flange Joint Three coils w/ rotational bc, bonded flange joint, 2T EM load Shear, normal force by region determines required friction coefficient Clamping force increased by addition of inboard bolts abint abinb Interface A-B inboard regions compression (blue) bolts added mu to prevent slip Normal pressure without inb bolts with inb bolts

Global Analysis (2) Additional inboard bolts reduces required coefficient of friction to 0.45 Bolts added to A-B (3), B-C (4), and A-A (2) interfaces

Friction Testing Additional bolts Friction tests with diamond, alumina shim coatings can increase mu to ~0.5 Design criteria limits value to 2/3 achievable or 0.3 Custom shims at interface B-C Standard shim concept

Location of Inboard Holes (1) Type-A, Flange Datum-D, Winding Side-A

Location of Inboard Holes (2) Type-A, Flange Datum-E, Winding Side-B

Location of Inboard Holes (3) Type-B, Flange Datum-D, Winding Side-A

Location of Inboard Holes (4) Type-B, Flange Datum-E, Winding Side-B

Location of Inboard Holes (5) Type-C, Flange Datum-D, Winding Side-A

Global Analysis w/ Equivalent Bolt Model Three coils w/ rotational bc, discrete attachments, sliding interface, 2T EM load Inboard bolts added, mu=0.3 Results show slipping w/ “residual” shear load taken by bolts Some shear loads >11-kips limit for bushing Interface A-B

Global w/ Bolts (2) Interface B-C

Global w/ Bolts (3) Load step difference (preload/EM) used to determine alternating bolt load Results preliminary, but suggest alternating load is ~8% of preload Interface A-A

Global w/ Bolts (4) Interface C-C No problem here

Conclusion Minimum friction condition (mu=0.3) does not work for all bolts, however both analyses indicate that the friction coefficient seen in testing is adequate Tests of bolted joint mockups are planned Additional analysis needed to check joint fatigue life LVDT connecting rods Test joint Shear Test Setup -K Freudenberg

Conclusion (2) The review objectives include... Define the location of additional inboard bolts Hole location drawings are being prepared. Finalize the material selection and design of the shim and washers Hardware models/drawings are in final final checking for procurement of tension and shear test joint components. Establish the minimum bolt preloads for both types of joint Preload defined according to design criteria. Access and tooling for bolt tightening is being evaluated. Establish the adequacy of the bolted joint design through analysis consistent with NCSX Structural and Cryogenic Design Criteria and the NCSX Handbook for Bolted Joint Design Bolt and joint have been shown to have adequate strength if friction is increased or other shear constraint is considered. Fatigue evaluation is in progress. Document the envisioned assembly sequence and assembly requirements Basic assembly sequence has been defined, but details TBD. Hole catalog and planned coil-to-coil fitup tests are critical.