Modular Coil AssemblyBolted 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-A4 plcs

A-B2 plcs

A-B3 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

insulatingbushing

insulatinglayer

Assembly Sequence (2)

3- Position coils and measure bushing 4- Fabricate and install bushing

Insulatingwasher

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-inD= 2.46-inL=1.93-inT= 1.75-inA286(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

-80000

-60000

-40000

-20000

0

20000

40000

60000

80000

100000

120000

0 10 20 30 40 50 60 70 80 90 100

System Load

Lo

ad

in

Me

mb

ers

Bolt Force

Joint Force

jointseparates at 90-kip

minpreload

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

inboardregions

compression(blue)

boltsadded

mu to prevent slip Normal pressure

withoutinb bolts

withinb bolts

Global Analysis (2)

Coefficent of Friction Needed to Prevent IL SlipCombined Coil Model (Mod/TF/PF)

Inboard Regions With and Without Added Bolts - Dead Load+EM+CD

0.000

0.150

0.300

0.450

0.600

0.750

0.900

cc2i

nt

cc2i

nb

bc2i

nt

bc2i

nb

ab2i

nt

ab2i

nb

aain

t

aain

b

abin

t

abin

b

bcin

t

bcin

b

ccin

t

ccin

b

Joint-Location

mu

• 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

Additionalbolts

• 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 LVDTconnectingrods

Testjoint

Shear TestSetup-K Freudenberg

Conclusion (2)

The review objectives include...

• Define the location of additional inboard boltsHole location drawings are being prepared.

• Finalize the material selection and design of the shim and washersHardware 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 jointPreload 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 frictionis increased or other shear constraint is considered.Fatigue evaluation is in progress.

• Document the envisioned assembly sequence and assembly requirementsBasic assembly sequence has been defined, but details TBD.Hole catalog and planned coil-to-coil fitup tests are critical.