Iqbal Shareef, Ph.D., CMfgE , P.E. Bradley University, Peoria, Illinois (309) 677-2981

www.nasa.govwww.bradley.edu

International Space Station SARJ Race Ring Damage Simulation and Durability Test

For Life Extension

Iqbal Shareef, Ph.D., CMfgE, P.E.Bradley University, Peoria, Illinois

(309) [email protected]

1

Presented at

NASA Academy of Aerospace Quality WorkshopCape Canaveral, Florida

March 22, 2012

mailto:[email protected]


Outline

• Overview of the International Space Station SARJ(Solar Alpha Rotary Joint)

• SARJ mechanism, tribology and contact mechanics• SARJ degradation and remedy

• Lab experiments to simulate and study the ongoing tribology condition of the SARJ– Goals of the experiments– Description of the test rig and test parameters– Typical test results and insights gained from experiments

• Summary

2


• International Space Station (ISS) is a research facility assembled in low Earth orbit. (~220 miles or 354 km from Earth)

• The ISS project is a multi-national effort led by• United States, with partners from Russia,

Canada, the European Union, Japan, and others.• Construction of the ISS began in 1998 and completed in

2011 with operations to continue until at least 2015, and likely 2020+

• ISS is the largest artificial satellite that has ever orbited the Earth, it can be seen with a naked eye

www.nasa.govwww.bradley.edu 4


• ISS is much longer than the length of Boeing 777. It is larger than 5BR house, weigh ~ 1 million lbs, and its 16 solar panels generate ~84 kW and cover more than 3 times the US Senate Chamber

• Since First Launch Nov 20, 1998– More than 1.8 billion statute miles on the odometer.– ~10 round trips to the Sun– ~70,000 orbits around the Earth– More than 105 launches to ISS– More than 200 visitors to ISS from 8 different countries– 67 Russian vehicles, 36 space shuttles, 2 European, 1

Japanese– More than 150 Spacewalks


International Space StationAs seen from the departing Space Shuttle Atlantis on May 23, 2010

Starboard SARJ

Port SARJ

Pressurized Modules

Sola

r Pa

nels


Space Station SARJ (Solar Alpha Rotary Joint)

The SARJ is a mechanism and is a structural assembly that transfers electricity from the arrays.


SARJ Assembly Overview


SARJ Race Rings and Rollers - Design Details Affecting the Tribology

9

• 12 rollers (following members) ~ 63 mm diameter, gold-plated 440C steel

• Race ring (driving member)~ 3.2 meter diameter, Nitrided 15-5 steel

• Normal load ~4.4 kN, nominal line contact length 21.5 mm

• Ring speed 1 revolution per orbit (~ 92 minutes)

• Initially operated without liquid lubricants

• Now operating with a grease(perfluorinated polyether type base oil + moly-disulfide)


Problem Statement and Objective

• ~ 83 days of operation, Starboard SARJ exhibited increased drive motor current and structural vibrations.

• EVA showed nitrided Starboard SARJ race ring had extensive damage.

• To reduce damage effect, astronauts lubricated the race ring with grease that significantly reduced drive motor current and structural vibrations.

• GRC simulated the race ring damage in dry running condition.

• GRC investigated the life of the lubricant in a simulated VRR.

• Objective is to find the # of cycles it takes for the grease to lose its effect.


Inspection of Starboard SARJ by Astronaut(After 83 days of operation)

11


Trundle Bearing Assemblies and Race Rings

12

Cross Section View

Starboard SARJ Race Ring

A B

C

Trundle Bearing Assembly SARJ


Alignment of Rollers with Race Ring

Overall Race Ring with Roller

Enlarged View of Aligned Roller

Enlarged View of Misaligned

Roller

Ft≈0

FsFt

Fs

Ft ≥ 0

Fs


Why is Roller Misalignment Important ?

misalignment angle (degrees)

-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5

axia

l for

ce /

norm

al lo

ad

-0.7-0.6-0.5-0.4-0.3-0.2-0.10.00.10.20.30.40.50.60.7

gold plated 440C vs nitrided 15-5bare 440C vs nitrided 15-5bare 440C vs nitrided 15-5 with grease

Thrust Force for 3 lubrication conditions and varying

misalignment angle - vacuum ~ 5x10-6 Torr

Axial Force(thrust force)


Why is Roller Misalignment Important ?( roller tipping )

Case “A”Axial Force = 0

Camber Axis

Case “B”Moderate Axial Force

Case “C”Large Axial Force

Roller

Race Ring

Roller Axis of

Rotation

Roller Roller

Race Ring Race Ring


Image from NASA/CP-2010-216272 (Almon, Wilkinson, Loewenthal),

Laboratory Observation of Roller Tipping


Contact Pressure

17

Contour plot of calculated pressure distribution for SARJ roller and raceway operating with a 4500 N normal load and 800 N axial load


Contact Pressure in Vacuum Roller Rig

18

Roller contact simulation and contour plot of calculated pressure distribution in GRC VRR operating with a 780 N normal load


Condition of the Nitrided RollerAfter the Damage Propagation Test

Loca

tion

1Lo

catio

n 2


Profile Inspections of the Nitrided 15-5 Roller at Circumferential Position #4.

20


NASA GRC Vacuum Roller Rig


NASA GRC Vacuum Roller Rig - Schematic

22

drive motor

ferrofluid sealsand bearings

“axial” force/thrust sensor

brake

pivot point for drive motor plate relative to turntable

bedplate

air piston

“normal load”force sensor

vac chamber

turntable

bedplate

bellows drive motor

ferrofluid sealsand bearings


brake


bedplate

air piston

“normal load”force sensor

vac chamber

turntable

bedplate

bellows

ferrofluid seal and bearing


brake

drive motor

bedplate

turntable on bearing

load cell for “tangential” force,mounted to turntable

ferrofluid seal and bearing


brake

drive motor

bedplate

turntable on bearing

load cell for “tangential” force,mounted to turntable



Use of the NASA GRC Vacuum Roller Rigto Simulate Ongoing Tribology Condition of SARJ

• Certain tribology conditions were matched well material type and manufacturing processes same type of grease able to match Hertz contact pressure misalignment angle of “X” on SARJ matched by ~”2X” angle on VRR

• Certain tribology conditions were not completely matchedX contact passing frequency on VRR ~60X greater compared to SARJX entraining velocities; VRR at 10 rpm ~ 19 mm/sec ; SARJ ~ 1.9 mm/sec

X space radiation, atomic oxygen X residual “atmosphere” in VRR (at 5 x 10-6 Torr)X space thermal conditionsX gravity effects ?


Testing Goals / Approach

24

• Keeping in mind the differences of VRR and SARJ, a parametric study was completed to determine relative effects and give qualitative understanding of expected SARJ behavior as grease loses effectiveness

• Parameters were varied systematically

• Rotating speed

• Normal load

• Misalignment angle Volume of grease applied

• 19 “lubrication interval tests” were completed (LIT1 – LIT19)


Normal Force, Thrust Force and Ratio of Ft/Fn for LIT 1-9LIT 1

LIT 6LIT 4

LIT 3LIT 2

LIT 5

LIT 7 LIT 8 LIT 9


LIT 10

LIT 15LIT 13

LIT 12LIT 11

LIT 14

LIT 16&17 LIT 18 LIT 19

Normal Force, Thrust Force and Ratio of Ft/Fn for LIT 10-19


Normal, Thrust, Ft/Fn from LIT3


Normal, Thrust, Fs/Fn from LIT3




Normal, Thrust, Ft/Fn from LIT16-17


Summary of 19 LIT Test ResultsTe

st N

ame

Rol

ler P

air

Mis

alig

nmen

t A

ngle

(Deg

)Sp

eed

(RPM

)

Bat

ch o

f Gre

ase

Am

ount

of

Gre

ase

(gm

)

Ave

rage

Nor

mal

Lo

ad F

n (lb

f)

Ave

rage

Thr

ust

Forc

e Ft

(lbf

)

Ave

rage

Sid

e Fo

rce

Fs (l

bf)

Tota

l # o

f Cyc

les

No.

of C

ycle

s to

Lo

se L

ub E

ffec

t

Ave

rage

cyc

les

to lo

ss o

f lub

e ef

fect

iven

ess

Cum

ulat

ive

tota

l cy

cles

on

rolle

r pa

ir

LIT 1 1st -1 40 A 0.140 184.27 -82.6 11.90 57,581 16,000LIT 2 1st -1 40 A 0.234 178.99 -46.7 11.63 102,207 70,000LIT 3 1st -1 40 A 0.314 181.21 -59.3 11.92 121,792 60,000LIT 4 1st -1 40 A 0.450 177.06 -74.6 11.36 121,042 16,000LIT 5 1st -1 40 A 0.356 186.97 -71.7 11.53 122,325 18,000LIT 6 1st -1 20 A 0.430 175.49 -66.3 9.81 92,616 19,000LIT 7 1st -1 9 A 0.295 174.49 -64.4 8.35 101,309 14,000LIT 8 1st -1 20 A 0.560 180.95 -72.8 9.49 60,024 38,000LIT 9 1st -1 10 A 0.550 183.55 -65.2 8.41 106,113 12,000 29,222 885,009LIT 10 2nd -1 9 A 1.482 181.91 -41.2 8.35 104,476 84,000LIT 11 2nd -1 20 A 1.486 188.08 -65.1 9.24 109,680 95,000LIT 12 2nd -0.5 20 A 1.411 192.35 -49.6 8.93 100,450 77,000LIT 13 2nd -0.5 10 A 1.400 190.43 -49 8.36 102,466 66,000LIT 14 2nd -1 10 A 1.589 99.73 -23.4 8.43 66,215 64,000LIT 15 2nd -1 10 B 1.617 107.08 -19.4 8.63 103,498 20,000LIT 16 2nd -1 10 B 1.390 106.00 -23.1 7.59 100,650 80,000LIT 17 2nd -1 10 B N/A Continuation of LIT 16 18,815 80,000LIT 18 2nd -1 10 B 1.354 192.30 -56.7 8.28 91,887 10,000LIT 19 2nd -1 10 B 2.048 189.49 -33 3.17 51,752 51,752 60,417 849,889


Conditions of Rollers after LIT9 and LIT19

Nitrided15-5PH

440C GoldAfter LIT9

Nitrided15-5PH

440C GoldAfter LIT19


Roughness and Wear After LIT 9m

icro

met

erm

icro

met

er


Roughness and Wear After LIT 18


Start Date, Time and Operator End Date, Time and Operator

Hours Test

No.

Ang

le (D

eg)

Spee

d (R

PM)

Nor

mal

Loa

d (v

)

Bat

ch o

f Gre

ase

Am

ount

of G

reas

e A

pplie

d (G

ram

s)

# of

Cyc

les

Tuesday August 03, 2010 - 11:00 Richard Wednesday August 04, 2010 - 12:00 Richard 25.00 LIT19-1 -1 10 2.5 B 2 15000Wednesday August 04, 2010 - 12:00 Richard Wednesday August 04, 2010 - 14:00 Richard 2.00 BWednesday August 04, 2010 - 14:00 Richard Wednesday August 04, 2010 - 17:00 Iqbal 3.00 LIT19-2 -1 10.26 2.5 B 0 1846Wednesday August 04, 2010 - 17:00 Iqbal Wednesday August 04, 2010 - 21:00 Iqbal 4.00 BWednesday August 04, 2010 - 21:00 Iqbal Thursday August 05, 2010 - 00:00 Richard 3.00 LIT19-3 -1 10.26 2.5 B 0 1846

Thursday August 05, 2010 - 00:00 Richard Thursday August 05, 2010 - 06:00 Richard 6.00 BThursday August 05, 2010 - 06:00 Richard Thursday August 05, 2010 - 09:00 Richard 3.00 LIT19-4 -1 10.26 2.5 B 0 1846Thursday August 05, 2010 - 09:00 Richard Thursday August 05, 2010 - 17:00 Iqbal 8.00 BThursday August 05, 2010 - 17:00 Iqbal Thursday August 05, 2010 - 20:00 Iqbal 3.00 LIT19-5 -1 10.26 2.5 B 0 1846Thursday August 05, 2010 - 20:00 Iqbal Friday August 06, 2010 - 08:00 Richard 12.00 B

Friday August 06, 2010 - 08:00 Richard Friday August 06, 2010 - 11:00 Richard 3.00 LIT19-6 -1 10.26 2.5 B 0 1846Friday August 06, 2010 - 11:00 Richard Friday August 06, 2010 - 13:00 Richard 2.00 BFriday August 06, 2010 - 13:00 Richard Friday August 06, 2010 - 16:00 Iqbal 3.00 LIT19-7 -1 10.26 2.5 B 0 1846Friday August 06, 2010 - 16:00 Iqbal Friday August 06, 2010 - 20:00 Iqbal 4.00 BFriday August 06, 2010 - 20:00 Iqbal Friday August 06, 2010 - 23:00 Richard 3.00 LIT19-8 -1 10.26 2.5 B 0 1846Friday August 06, 2010 - 23:00 Richard Saturday August 07, 2010 - 05:00 Richard 6.00 B

Saturday August 07, 2010 - 05:00 Richard Saturday August 07, 2010 - 08:00 Richard 3.00 LIT19-9 -1 10.26 2.5 B 0 1846Saturday August 07, 2010 - 08:00 Richard Saturday August 07, 2010 - 16:00 Iqbal 8.00 BSaturday August 07, 2010 - 16:00 Iqbal Saturday August 07, 2010 - 19:00 Iqbal 3.00 LIT19-10 -1 10.26 2.5 B 0 1846Saturday August 07, 2010 - 19:00 Iqbal Sunday August 08, 2010 - 07:00 Richard 12.00 B

Sunday August 08, 2010 - 07:00 Richard Sunday August 08, 2010 - 10:00 Richard 3.00 LIT19-11 -1 10.26 2.5 B 0 1846Sunday August 08, 2010 - 10:00 Richard Sunday August 08, 2010 - 12:00 Iqbal 2.00 BSunday August 08, 2010 - 12:00 Iqbal Sunday August 08, 2010 - 15:00 Iqbal 3.00 LIT19-12 -1 10.26 2.5 B 0 1846Sunday August 08, 2010 - 15:00 Iqbal Sunday August 08, 2010 - 19:00 Iqbal 4.00 BSunday August 08, 2010 - 19:00 Iqbal Sunday August 08, 2010 - 22:00 Richard 3.00 LIT19-13 -1 10.26 2.5 B 0 1846Sunday August 08, 2010 - 22:00 Richard Monday August 09, 2010 - 04:00 Richard 6.00 B

Monday August 09, 2010 - 04:00 Richard Monday August 09, 2010 - 07:00 Richard 3.00 LIT19-14 -1 10.26 2.5 B 0 1846Monday August 09, 2010 - 07:00 Richard Monday August 09, 2010 - 15:00 Iqbal 8.00 BMonday August 09, 2010 - 15:00 Iqbal Monday August 09, 2010 - 18:00 Iqbal 3.00 LIT19-15 -1 10.26 2.5 B 0 1846Monday August 09, 2010 - 18:00 Iqbal Tuesday August 10, 2010 - 06:00 Richard 12.00 BTuesday August 10, 2010 - 06:00 Richard Tuesday August 10, 2010 - 09:00 Richard 3.00 LIT19-16 -1 10.26 2.5 B 0 1846Tuesday August 10, 2010 - 09:00 Richard Tuesday August 10, 2010 - 11:00 Richard 2.00 BTuesday August 10, 2010 - 11:00 Richard Tuesday August 10, 2010 - 14:00 Richard 3.00 LIT19-17 -1 10.26 2.5 B 0 1846Tuesday August 10, 2010 - 14:00 Richard Tuesday August 10, 2010 - 18:00 Iqbal 4.00 BTuesday August 10, 2010 - 18:00 Iqbal Tuesday August 10, 2010 - 21:00 Iqbal 3.00 LIT19-18 -1 10.26 2.5 B 0 1846Tuesday August 10, 2010 - 21:00 Iqbal Wednesday August 11, 2010 - 03:00 Richard 6.00 B

Wednesday August 11, 2010 - 03:00 Richard Wednesday August 11, 2010 - 06:00 Richard 3.00 LIT19-19 -1 10.26 2.5 B 0 1846Wednesday August 11, 2010 - 06:00 Richard Wednesday August 11, 2010 - 14:00 Richard 8.00 BWednesday August 11, 2010 - 14:00 Richard Wednesday August 11, 2010 - 17:00 Iqbal 3.00 LIT19-20 -1 10.26 2.5 B 0 1846Wednesday August 11, 2010 - 17:00 Iqbal Thursday August 12, 2010 - 05:00 Richard 12.00 B

Thursday August 12, 2010 - 05:00 Richard Thursday August 12, 2010 - 08:00 Richard 3.00 LIT19-21 -1 10.26 2.5 B 0 1846

A Test Plan to Investigate Influence of “Strategic Pauses” (this required actions at odd hours; special thanks to Mr. Richard Manco)




Results of the LIT Tests

• During LIT 1-9 the average number cycles for lubricant to become ineffective was 29,200 cycles using first pair of rollers.

• During LIT 10-18 experiments the average number cycles for lubricant to become ineffective was 60,400 cycles.


Results of the LIT Tests

• During the LIT1-9 experiments there were more than 885,000 rotations using the first pair of rollers.

• During LIT 10-19 there were more than 850,000 rotations without significant damage to render the rollers functionless.

Note: SARJ makes nearly 96,000 rotations per year.


Summary

• SARJ was vulnerable to inadequate lubrication• Large friction can produce SARJ roller tipping• Relative effects of operating parameters were studied by test• Loss of lubrication effectiveness was determined from the rise

of the axial force to a critical value• The most influential parameter was the mass of grease applied • “Strategic pauses” were effective to extend lube effectiveness

in the VRR and be an effective strategy for SARJ


Acknowledgements

Dr. Alice Smith Professor and Chair of IE at Auburn

Dr. Timothy L. Krantz Scientist S&T Division at NASA GRC

Dr. Phil Abel Asst. Chief, S&T Division at NASA GRC

Dr. Jim Zakrajsek Chief of S&T Division at NASA GRC,

Dr. Richard Johnson Dean College of E&T at Bradley University

40



Back up Slides

42


Condition of rollers after lab testing to simulate SARJ ring operating with a combination of "tipped" and "not tipped" rollers

Ref: NASA Technical Memorandum, to be published, draft manuscript under review


References

• “Investigation Of The Vacuum Tribological Property Of Damaged Surfaces In Presence Of Grease,” 2011 STLE Annual Meeting & Exhibition, Control ID: 980140, Category: Grease, Atlanta GA, May 15-19, 2011. by Timothy Krantz and Iqbal Shareef.

• NASA CP-2010-216272 (Conference Proceedings, includes three reports related to SARJ)

• “Roller Testing to Mimic Damage of the ISS SARJ Ring and Durability Test to Simulate Fifteen Years of SARJ Operation Using the Damaged Surface”; NASA TM (under technical review) by Krantz; Elchert; DellaCorte, Dube and Stanford

•“The ISS SARJ Bearing Failure and Recovery: Technical and Project Management Lessons Learned”; NASA TP (under technical review) by DellaCorte, Krantz, and Dube

44


Spacewalks to Clean and Lubricate the SARJ Mechanismswere Successful, and Systems are Operating Well

• Will the SARJ mechanism require additional applications of grease ? • Can we expect “warning signs” that the lubrication condition is

becoming inadequate?


Dr. Iqbal Shareef and Michael Freeman

46

Documents

Iqbal Shareef, Ph.D., CMfgE , P.E. Bradley University, Peoria, Illinois (309) 677-2981