NASA Infrared Telescope Facility. Author: Institute for Astronomy University of Hawaii

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1 NASA Infrared Telescope Facility Author: Institute for Astronomy 2/16/2016 Morgan Bonnet 1 University of Hawaii

2 IRTF Upgrades - Dome drive system - Refurbishing of the dome rail - Primary mirror re-aluminization - HVAC system - Shutter drive (Alimak) - TCS upgrades - MIM re-inforcement - Telescope Balancing - Dome re-painting (not started, contracting ongoing) - Instrumentation 2/16/2016 2

3 Primary Mirror Re-aluminization 2/16/2016 3

4 Dome Drive System: Description - 12 bogie wheels at ~30 deg - Including 3 drives - 1 circular rail made of 12 sections - 24 guide rollers (Guide roller lip in rail groove => earthquake) 2/16/2016 4

5 Dome Drive System: Section View Guide Roller Dome Rail Spring Plate Bull Gear Bogie Wheel 2/16/2016 5

6 Root Causes: Ishikawa Diagram 2/16/2016 6

7 Main Root Causes Loose Spring Plates / uneven Rail bottom surface: => Improper tracking = Dome becomes off-centered rapidly => heavy loads on Guide Rollers (Bogie Wheel or/and Rail) => wedge effect Shortened Rail: => Contact between top of Guide Roller with top of Rail groove Worn down Bogie Wheel (due to contact with guide roller) => Contact between bogie wheel and spring plate Insufficient Motor Torque / inefficient Motor Control: => Dome can t pass hard spots, especially at low speed (insufficient Momemtum) => Improper tracking Accelerated Wear (vicious circle) 2/16/2016 7

tangent to the Rail - To insure that guide rollers aren t allowing the wheels to touch the spring plates (Remark:

8 Action Items (1/4) General Maintenance / Complete Check up: - To insure that issues aren t simply originating from a damaged bearing or lack of grease (no issue found) Bogie Wheels and Guide Rollers Tuning: - To insure wheels are tangent to the Rail - To insure that guide rollers aren t allowing the wheels to touch the spring plates (Remark: action is being repeated as needed) Damaged Bogie Wheel replacement: - Reduce sideways movement range of wheel 2/16/2016 8

Action Items (2/4) Spring Plates retightening and readjustment: - To insure proper tracking and to help

spring plates ) Dome Height Adjustment: - To re-center the guide roller s lip in the middle of the rail

the drive wheels: since the drive wheels can t be raised any further due to their bull gear, by placing

9 Action Items (2/4) Spring Plates retightening and readjustment: - To insure proper tracking and to help keeping the dome centered (Remark: the dome needs to be supported from the concrete ground to work on the spring plates ) Dome Height Adjustment: - To re-center the guide roller s lip in the middle of the rail groove - On the non-drive wheels: by raising the wheel height using the stud shaft adjustment nut - On the drive wheels: since the drive wheels can t be raised any further due to their bull gear, by placing shims under their spring plate and replacing the guide rollers with newly designed ones (lowered lip) 2/16/2016 9

10 Action Items (3/4) Dome Drive Motors Upgrade: - 2x more torque and across full speed range (Cont. Stall Torque: 10 ft-lb / Peak Torque: 31 ft-lb.) - Improved Control Strategy: speed based control with anti torque runaway function instead of torque based. 2/16/

Action Items (4/4) Rail Resurfacing: (Remark: Cold flown rail debris buildup was already grinded down) - Rail tracking improvement - Elimination of the dips (constant rail height) In-situ machining

11 Action Items (4/4) Rail Resurfacing: (Remark: Cold flown rail debris buildup was already grinded down) - Rail tracking improvement - Elimination of the dips (constant rail height) In-situ machining needed. Required a special custom setup. A Request for Proposal was written and several vendors were identified. A local machine shop was chosen for the contract. Very long and complicated process which took over a year. 2/16/

12 Dome Drive Improvements: Rail Resurfacing Setup: Grinder Attachment to Dome Station Pier Motor Hydraulic System to adjust grinder height

13 Dome Drive Improvements: Rail Resurfacing After 1 st Roughing Pass After 0.19 of Material Removed. Most of the rail was cleaned up. Worst/Last spot after 0.23 of Material Removed. Finish Pass Quality Worst/Last spot after of Material Removed. 13

Dome Drive Improvements: Rail Resurfacing Servo Motor

current distribution) AMP Servo Motor Currents AFTER

current by about 50% Most of the current values are now

14 Dome Drive Improvements: Rail Resurfacing Servo Motor Currents BEFORE resurfacing: (Histogram showing the current distribution) AMP Servo Motor Currents AFTER resurfacing: AMP AMP Rail Resurfacing reduced the needed current by about 50% Most of the current values are now under 11.4 amps, well within the rated current for the motors. 14 AMP

15 MULTIPLE INSTRUMENT MOUNT (MIM)

16 MULTIPLE INSTRUMENT MOUNT (MIM)

17 MULTIPLE INSTRUMENT MOUNT (MIM)

18 MULTIPLE INSTRUMENT MOUNT (MIM) UPGRADE In preparation to adding a new instrument (ISHELL) to the facility, we needed to insure that the current structure could support it. Quartus Engineering was selected with a RFP to perform a structural analysis of the MIM: Goal: verify that the addition of ishell can be supported by the existing system. if calculated strengths are below safety margins, identify components to be re enforced or re designed. Method: static, seismic and fatigue FEA analysis

MIM STRUCTURAL ANALYSIS Components that are explicitly modeled include: Mirror Cell Plates (8X) Interface Boxes w/ Shims (4X) MIM Quadmount Weldment North Rail Assembly Mirror Cell Plate Cabinet and

19 MIM STRUCTURAL ANALYSIS Components that are explicitly modeled include: Mirror Cell Plates (8X) Interface Boxes w/ Shims (4X) MIM Quadmount Weldment North Rail Assembly Mirror Cell Plate Cabinet and Electronics MIM Weldment Cooler I/F Box North Truck Cabinet Support Weldments (4X) Components that are modeled as concentrated masses attached via rigid elements include: West, South, and East Rail Assemblies and Trucks Coolracks Cabinets & Electronics (4X) Cabinet Support Weldment Coolracks Coolers (2X) Instruments (4X) North Truck Instrument ishell Instrument North Rail Assembly 19

20 MIM SEISMIC ANALYSIS: OVERVIEW Structure analyzed in 3 different orientations: Zenith: DEC = 19 N; RA = 0 Horizon East: DEC = 19 N; RA = 60 E Horizon Southeast: DEC = 31 S; RA = 60 E Seismic loads of 0.95G Horizontal and 1.14G Vertical are applied to the structure in each orientation: Load levels and directions calculated using ASME code 9 load cases total analyzed: 3 telescope orientations X 3 earthquake horizontal directions Von Mises Stresses are recovered from shell elements Forces are recovered from weld lines, fasteners, and truck wheels Weld material strengths receive a knockdown factor of 0.6 Safety factors used for margin of safety calculations are defined in AISC: Safety factor of = 1.67 used for: Material Von Mises yield Safety factor of = 2.0 used for: Material Von Mises ultimate & bearing stress Weld tensile & shear stress Fastener stress (tensile yield, tensile ultimate, shear ultimate) Fastener gapping and slipping Truck wheel axial & radial loads 20

MIM SEISMIC ANALYSIS Material Stress Summary Conclusion: Mirror Cell Plates, Interface Boxes and Rail Support need to be reenforced Rail was later

21 MIM SEISMIC ANALYSIS Material Stress Summary Conclusion: Mirror Cell Plates, Interface Boxes and Rail Support need to be reenforced Rail was later verified as being hardened, so margin are actually positive. No change needed. Fasteners size to be increased at the Interface Box / Shim junction.

around 3 rd bolt on mirror cells INTERFACE BOXES: Min. Margin of Safety: 0.43 yield; 0.23 ultimate Max. Stress = 37.

22 MIM SEISMIC ANALYSIS Material Stress Details (Negative Margins) MIRROR CELL PLATE: Min. Margin of Safety: 0.26 yield; 0.01 ultimate Max. Stress = 29.2 ksi (Horizon East) Occurs on upper interface to mirror cell around the top bolt Bolted joint takes 6150 lb of shear load Negative margins show in all 3 telescope orientations Always located around 3 rd bolt on mirror cells INTERFACE BOXES: Min. Margin of Safety: 0.43 yield; 0.23 ultimate Max. Stress = 37.7 ksi (Horizon East) Occurs on upper interface to mirror cell at junction of 3 welded plates Major load path for center bolt to MIM as well as outer bolt to shim Three negative margin locations exist in I/F boxes: Welded plates 3 way junction (37.7 ksi) Bolted joints to mirror cell (27 ksi) Bolted joints to shim (37 ksi)

MIM SEISMIC ANALYSIS Material Stress Details (Negative Margins) RAIL SUPPORT ASSEMBLY: Min.

3 ksi (Horizon East) Occurs on rail mount aligned near center of truck Peak stress is driven by bending in

rail support assembly material FASTENERS (Interface Box to Shim) Negative gapping and stress margins exist in

08 Tensile yield stress margin = 0.26 Tensile ultimate stress margin = 0.

23 MIM SEISMIC ANALYSIS Material Stress Details (Negative Margins) RAIL SUPPORT ASSEMBLY: Min. Margin of Safety: 0.48 yield; 0.30 ultimate Max. Stress = 41.3 ksi (Horizon East) Occurs on rail mount aligned near center of truck Peak stress is driven by bending in rail mount flange Negative margins show in all 3 telescope orientations Positive stress margins in all other rail support assembly material FASTENERS (Interface Box to Shim) Negative gapping and stress margins exist in bolts from interface boxes to shims Gapping margin = 0.41 Shear ultimate stress margin = 0.08 Tensile yield stress margin = 0.26 Tensile ultimate stress margin = 0.15 These smaller bolts react a large portion of the moment induced by the MIM Wide rectangular pattern forces them to take more load than the central 3/4 10 bolt to the MIM Bolt size = 3/8-16 Max axial force = 7821 lb Max shear force = 4012 lb

24 Structure analyzed in two telescope orientations MIM FATIGUE ANALYSIS: OVERVIEW Horizon Southeast: DEC = 31 S; RA = 60 E Horizon Northwest: DEC = 59 N; RA = 60 W Fatigue load of 1G applied in the gravity direction Fatigue analysis performed for 90,000 cycles (10 cycles/night, 300 nights/year, 30 year lifespan) For steel components (including welds), AISC gives a variety of fatigue strengths based on the location of the material (bolted joint, welded joint, etc) Stress ranges are determined for the maximum to minimum stresses that the structure sees as it moves from Horizon Southeast to Horizon Northwest orientation Forces are recovered from weld lines and truck wheels No safety factors are used for fatigue analysis as specified in AISC Bolted joints will not fatigue as long as joint does not gap

25 MIM FATIGUE ANALYSIS Material Stress Summary Same conclusion as for the Seismic Analysis. Upgrades needed for the same components. 25

26 MIM RE-ENFORCEMENT Increased Plates thickness Increased weld filets width Increased fasteners size Added 4 side braces All fasteners minimum Grade 8 26

27 MIM RE-ENFORCEMENT WORK SCHEDULE Re-design + Drawings Fabrication Preparation: Cable labeling, remove unscheduled instruments, Telescope Shutdown: OCT 19 th 29 th 2015 Preparation work: (4 days) - Remove Electronic cabinets, chillers, instrument - Lower MIM onto platform - Prep welding area - Protect Primary mirror Welding work: (4 days) - Cut-out old interface plates (x4) - Weld new interface plates (x4) Telescope Re-assembly: (3 days) Other parallel tasks: - Chillers Fans upgrade (6 days max) - SpeX work (8 days max) Note: Contingency built-in within different Tasks Oct 30 th = engineering = add l day of contingency 27

28 TELESCOPE BALANCING SYSTEM Movable Counterweights 28

29 TELESCOPE BALANCING SYSTEM Movable Counterweight locations 29

30 TELESCOPE BALANCING SYSTEM Fixed Counterweights 30

31 TELESCOPE BALANCING MODEL AND OPTIMIZATION TOOL Goal: - verify that the existing system can still be balanced after the addition of ISHELL - optimize the location and amount of the static counterweights - predict optimal location of the movable counterweights Method: - calculate sum of moments on the RA and DEC axis. Run theoretical balancing routine to find the smallest possible moments by moving the movable counterweights. 31

32 TELESCOPE BALANCING MODEL AND OPTIMIZATION TOOL 1) Model Inputs: Fixed values: - Masses: calculated/estimated from CAD model or measured - Center of Gravity: calculated/estimated from CAD model Parameters: - Instruments CoG: stowed and operation - Movable Counterweight: range and orientation vector Existing balanced configurations: - to determine / estimate unknown weights - Allocate Dummy Weights to compensate for approximations 2) Model Outputs: DEC and RA Moments (are they small enough to allow for stable telescope tracking?) Movable counterweights positions (and corresponding voltages) 32

33 TELESCOPE BALANCING MODEL AND OPTIMIZATION TOOL 3) Model Calculations: Moments are calculated for each component Assume movable CWs are centered DEC axis moments Zenith pointing M = W*y 90 South pointing M = W*z M = moment [in*lb] W = weight [lb] [x,y,z] = [x,y,z]-direction coordinate of CoG [in] RA axis moments Zenith pointing M = W*x 19 South, 90 East pointing (DEC and RA axes are perpendicular to each other) For components on CS: M = W*(z+7.992) For components on YK: M = W*( y*sin(19 )+z*cos(19 )+7.992) Sum moments for each axis in both orientations (4 moment sums total) DEC axis only sums components on CS RA axis sums components on CS and YK Use movable counterweights to try and zero moment balances 33

34 TELESCOPE BALANCING MODEL 4) Balancing steps: AND OPTIMIZATION TOOL Step 1: DEC 90 South Pointing (Tube Top/Bottom Balance) Calculate optimal position for the following Movable Counterweight Tube Vertical SW Tube Vertical NW Tube Vertical SE Tube Vertical NE Step 2: DEC Zenith Pointing (North/South Balance) Calculate optimal position for the following Movable Counterweight Tube Horizontal Bottom Tube Horizontal Top Step 3: RA 19 South, 90 East Pointing (Yoke Top/Bottom Balance) Calculate optimal position for the following Movable Counterweight Yoke Vertical W Yoke Vertical E Step 4: RA Zenith Pointing (East/West Balance) Calculate optimal position for the following Movable Counterweight Yoke Horizontal Center Yoke Horizontal S Bottom Yoke Horizontal S Top 34

35 TELESCOPE BALANCING MODEL AND OPTIMIZATION TOOL 35

36 TELESCOPE BALANCING METHOD Model is missing too much data (weight, CoG) or estimates are too far off to determinate the dummy weight accurately. Optimization of the static CW locations can still be done by hand For each instrument configuration, the movable CWs which are maxed out indicate where the unbalance resides. (Yoke or Tube Top/Bottom, North/South, East/West) Then, static CWs are added/removed to compensate. The telescope balancing procedure is run again to find new movable CWs locations Repeat until none of the configurations have maxed out movable CWs. Model equations can be used to predict the amount of static CWs to be added/removed. 36

Chapter 11. Keys, Couplings and Seals. Keys. Parallel Keys

Chapter 11. Keys, Couplings and Seals. Keys. Parallel Keys Chapter 11 Keys, Couplings and Seals Material taken for Keys A key is a machinery component that provides a torque transmitting link between two power-transmitting elements. The most common types of keys