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.