Zakrajsek, James J.

NASA Technical Reports Server

Tribology & Mechanical Components 
Branch Overview!
!
James J. Zakrajsek!
Dr. Robert F. Handschuh!
NASA Glenn Research Center!
Cleveland, Ohio, U.S.A.!
https://ntrs.nasa.gov/search.jsp?R=20150010188 2019-08-31T07:43:41+00:00Z
Topics 
•  View from 30,000 feet 
•  Structures and Materials Division 
•  Tribology & Mechanical Components Branch 
•  Drive system activities 
•  Summary 
NASA Glenn Research Center!
Aeroshells 
TPS; Cooled strs. 
Cryogenic tanks 
Nacelles 
Combustors 
Engine fan system 
Mechanisms 
Oil-Free engines 
Injectors 
High-power motors 
Space lubricants 
Protective Coatings 
Sensors 
Thermoelectrics 
Surface mobility systems 
Nozzles 
In-space & on-surface modules 
Rotor discs and systems 
Turbine vanes 
Energy absorbing systems 
Mechanical drive systems 
Human health systems 
Thrusters 
Bearings and flywheels 
Solid oxide fuel cells, batteries 
High temp. and cryogenic seals 
Porous membranes 
BN nanotubes 
 
 Probabilistic methods     Matl. and strl. Concepts       Design technology     
  Mechanical power transfer   Health prognostics       Experimental methods
 Impact dynamics   Blast mechanics       Measurement technology 
 Structural mechanics          Structural dynamics       Aeroelasticity 
         Material modeling   Joining technology       Durability and life   
 Material characterization   Failure and damage growth     Fatigue and fracture 
         Functional materials   Processing technologies         High temp. and cryo seals 
         Metallic alloys   Shape memory alloys               Ceramic materials                   
         Computational materials   Protective coatings                   Multifunctional Materials 
         Surface science   Extreme environment effects   Lubricant chemistry 
         Materials science   High temperature chemistry     Friction and wear 
  
Materials and Structures Division Capabilities for !
Aeronautics  and Exploration Systems"
Advanced Drive 
Systems 
Advanced Thermal 
Barrier Seals 
Actively 
Controlled 
Nozzle 
Oil-Free Foil 
Gas Bearings 
Energy Absorbing 
Systems 
Engine 
Components 
Propulsion and Power System Components!
Cryo Tanks 
Nanotubes GRCop Thrust 
Chamber 
Materi ls and Structures Division!
Core R&T Capabilities!
Tribology & Mechanical Components Branch 
 
!
!
Heat Shield 
Interface Seal 
Docking Seal 
Aerospace Seals Research !
•  Space habitat seals for extreme environments 
•  Structural / thermal protection seals 
•  Non-contacting turbine seals 
•  Accelerated space lubricant life testing under vacuum 
•  New mechanism concepts for planetary environment 
•  New space lubricant development 
•  Terramechanics modeling & testing for efficient wheels 
 
Space Mechanisms & Lubrication!
Aero Drive Systems !
•  Gear fatigue research 
•  High speed gear lubrication 
•  Drive system diagnostics  
•  Fatigue crack modeling 
•  Dynamic mechanical components 
•  Rotorcraft transmission systems  
•  Advanced rolling element and 
wave bearing technologies 
Advanced Bearing Technology !
•  Aero / Space application 
•  World-leading bearing experts 
•  Advanced modeling methods 
•  Foil bearing predictive design 
From basic 
research to 
application 
Tribology & Mechanical Components Branch 
"
Branch Teams: 
Ø  Advanced Bearings 
Ø  Space Mechanisms & Lubrication  
Ø  Aerospace Seals   
Ø  Aero Drive Systems 
Aero Drive System Team Mission is to conduct basic research 
and technology on mechanical components and drive systems.  
Results lead to first principal understanding of complex 
phenomena of component or system operation in normal and 
extreme conditions.  Technology transfer results in improved 
operation efficiency and safety of Subsonic Rotary Wing 
Aircraft.  
   
Drive System Legacy Test Facilities 
Spur Gear Fatigue Test Rigs Spiral Bevel / Face Gear Test Facilities Gear Noise / Dynamics Test Facility 
Split Torque Test Facility OH-58 Transmission Test Facility High Speed Helical Gear Train Facility 
Drive System Analytical Capabilities 
•  Finite element, boundary element, finite difference  
  modeling used for structural and thermal analysis 
•  Condition based maintenance signal analysis tools 
•  Computational fluid dynamics analysis tools  
Finite Element Analysis of Spiral Bevel Gear" CFD Analysis of spur gear 
operating at high"
rotational speed."
Technologies for Propulsion – Drive Systems 
•  Advanced Drive System Components and Systems	

–  Multi / variable speed drives 	

–  Improved gear alloys	

–  Enhanced gear operation / control 	

–  Composite material application to dynamic components	

–  Non-traditional materials (Ni-based, ceramic,…)	

–  Modified geometry gear design, bearings & system arrangements	

–  High temperature operation of drive systems	

	

•  Lubrication Technology	

–  Improved loss-of-lubrication (longer time, lighter weight,…)	

–  Reduced power loss – windage drag reduction	

	

•  Condition Based Maintenance – HUMS	

–  Improved detection techniques – i.e. non-metallic sensors	

–  Improved data algorithms	

–  Validated methods – rotorcraft field verification 	

	

•  Up to 10,000 rpm, 220+ ft⋅lb torque (new test 
rigs) 
•  Investigate effect of material, heat 
treatments, surface treatments, tooth profiles, 
contact ratio, lubricant chemistry, ………. 
Legacy Test Rig" New Test Facilities"
Gear Contact Fatigue Testing 
Example Test Gear"
 "Single Tooth Bending Fatigue 
•  Unique single tooth bending capability 
•  Operation up to 1000 Hz 
•  Heated – cooled test capability 
•  Conduct test without removing adjacent teeth 
Hybrid Bearing Test Facility 
•  150 hp, 21,000 rpm motor	

•  Test bearing subjected to 
variable axial and radial 
loads	

•  Oil debris monitoring and 
vibration instrumentation 	

•  Test bearing isolated from 
drive-train vibration by fluid 
film bearings	

•  Near term to conduct hybrid 
bearing fatigue experiments 
and diagnostics, data fusion	

•  1 input, 1 output, each 250 hp and 15,000 rpm maximum 
•  Concepts for variable/multi-speed drive developed and down-
selected, then tested in this facility 
•  Positive feedback from industry on variable speed drive-train  
technologies for rotorcraft   
GRC Leveraged Rigs and Facilities:  
Variable Speed Transmission Rig	
Variable / Multi-speed Test Facility 
Multi-Speed Concepts!
Offset Compound Gear Drive with Dry Clutch 
Two gear drive arrangements: Offset Compound Gear Drive and Dual Star   
                                                 Idler Planetary 
 
Two clutch configurations: Dry and Wet Clutch 
NASA Windage Test Results!
Single Gear Test Results 
(13 inch pitch diameter gear) 
Penn State University Analysis Comparison 
(NRA) 
PSU Analysis to NASA 
Results Comparison 
Possible Performance  
Improvement - Trailing  
Surface Ramp 
NASA GRC Loss of Lubrication Evaluation 
Post-Test: Gear that failed "
Failed 6 
minutes"
Successful operation 
> 1 hour"
3x increase in mist flow rate 
Objective/Approach: 
 
•  Validate gearbox dynamic model 
•  Model developed at Penn State University 
NRA, two-speed Chariot gearbox modeled. 
•  Experimental tests performed on Chariot 
gearbox 
•  Dynamics during up-shift and down-shift 
measured and compared to predictions 
Two-Speed Gearbox Dynamics 
Load 
Disk Pack 1 Disk Pack 2 
Motor 
Motor 
Gears Gears 
Two-Speed Gearbox Dynamics	

Test
Gearbox
output
speed
(rpm)
0
100
200
300
Simulation
Time, sec
0 2 4 6 8
Gearbox
output
speed
(rpm)
0
100
200
300
Test
Gearbox
output
torque
(lb-in)
0
200
400
600
800
1000
Simulation
Time, sec
0 2 4 6 8
Gearbox
output
torque
(lb-in)
0
200
400
600
800
1000
Smart Gear – Feasibility Experiment!
•  Mechanical components are beginning to get ‘smart’ 
o  Future components will have integrated sensors, actuators, and communication. 
  
•  To counteract gear induced noise in helicopters, a ‘Smart Gear’ is being developed 
o  Noise originates between gear teeth, and takes numerous paths to the cabin. 
o  Smart Gear would sense and actively counteract noise at the source. 
•  Feasibility depends on ability to generate counteracting vibration on a rotating gear 
Counter-vibration actuators in 
gear body!
Simulated source on 
tooth!
First prototype under construction!
Magnetic gearing – exploratory work!
Magnetic teeth!
Overload plate!
Torque transfer without  
contact!
•  Gears create mechanical advantage in the drive system 
o  E.g. Helicopter engine torque is increased by 20x or more  
•  Tooth contact generates noise, and failures from wear and heat. 
o  Oil lubrication is needed for gears to survive. 
•  Magnetic gearing is being explored to eliminate tooth contact. 
o  Experiments demonstrate that magnetic gears can be virtually silent. 
o  Permanent magnets cannot sustain high torque 
o  Electromagnetic gears should be explored. 
Hybrid Gear !
• Weight: 0.8847 lbs !
• Machined away steel 
from web and hub 
(hexagonal shape)."
"
• Weight: 0.7081 lbs !
• Applied 36 layers of 
the composite system 
into 3 sections "
Bonded 
interfaces"
"
Spur Gear Testing Facility	

Driver Gear 	
 Loaded Gear	

Accelerometers	

Hybrid Gear Testing!
Status:  "
•   Gears currently undergoing dynamic – fatigue test "
•   Vibration tests completed"
•   Processing improvements identified"
•   Other applications identified"
CBM Functions	

Propulsion System Health	

•  Health monitoring of dynamic mechanical components 	

•  Monitored by vibration signature analysis methods (condition indicators-CI) 
and oil condition	

Structural Health	

•  Fatigue life management/component lifing based on actual usage & regime 
recognition	

Exceedance Monitoring	

•  Aircraft operational/parametric data (torque, speed, temperature)	

Engine Perfromance	

•  Power assurance check/Power Management	

Rotor Smoothing	

•  Automated track & balance of rotors to decrease vibrations	

Fleet Maintenance	

•  Logging maintenance actions/CBM data	

	

	

Propulsion System Health	

–  Improved detection techniques	

–  Improved diagnostic algorithms	

•  Multi-sensor data fusion	

•  Performance metrics	

•  Damage magnitude assessment	

–  Validated methods – rotorcraft field verification 	

•  Test methods representative of fielded faults	

–  Future prognostic algorithms	

•  Damage life prediction models – predict remaining useful life	

Structural Health & Exceedance Monitoring	

–  Correlate aircraft operational parameters to component life.  	

	

Research enabled through Partnerships with the FAA and US Army	

–  FAA funded Space Act Agreements	

–  Access to > 2000 Army HUMS equipped helicopters	

	

   	

	

	

	

NASA GRC CBM Focus !
Planetary Fault Detection	
 
Objective: 	

Demonstrate diagnostics to detect gear and bearing planetary system faults in 
main-rotor gearbox	

Approach	

Develop vibration algorithms from seeded fault tests on the OH-58 main-rotor 
transmission (AATD/Bell OSST)	

Propulsion System Health!
Bearing Fault Detection Methodology	

Magnitude
0
5000
10000
15000
Accelerometer number
A1 A2 A3 A4 A5 A6 A7 A8
Magnitude
0
5000
10000
15000
20000
Planet Bearing Fault Detection!
Outer-race frequencies!
Outer-race 
defect!
Inner-race frequencies!
Inner-race 
defect!
Healthy!
28 
Time Domain	

Frequency Domain	

time steps"
"
undamaged	

damaged	

Su
n G
ea
r D
isp
lac
em
en
t 	

	

Objective: 	

Develop analysis method to simulate 
dynamic response of gear or bearing surfaces 
with damage	

	

	

	

	

	

Approach:  
• Defect geometries defined by actual 
measurements	

• Forces between components calculated via 
contact mechanics	

• Deformations and vibration responses 
calculated via finite element	

• Bearing module also available	

Propulsion System Health!
	

Objective: 	

•  Demonstrate (CI) responds to 
failure progression  & correlates to 
remaining useful life 	

Approach: 	

•  UH60 tail gearbox output shaft 
thrust bearings 	

•  Removed from helicopters 
installed in test stand	

•  Periodic inspections to measure 
spall growth	

•  CI data mapped to the damage 
state did not perform well for 
magnitude assessment	

•  Oil debris sensor monitored debris 
generation & indicated 
progression & remaining life.	

	

Propulsion System Health!
Summary!
•  Three main R&D focus areas at NASA Glenn: 
  * Advanced Components and Systems 
  * Lubrication Technologies  
  * Condition Based Maintenance 
•  Currently conduct / manage research within our 
center as well as at contractor and university 
locations 
•  Involved in analytical and experimental 
developments 
•  Work closely with the space & aerospace industry, 
other government agencies / NASA centers, …. 


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