Tribology Challenges in the Aerospace Industry

Transcription

1 Tribology Challenges in the Aerospace Industry Ulf Jonsson United Technologies Research Center Presented at the LTU Tribology Days September 26-27, 2013 This page contains no technical data subject to the EAR or the ITAR.

2 United Technologies? The biggest company you never hear about. UTC Climate, Controls & Security Otis Sikorsky Pratt & Whitney UTC Aerospace Systems Segment 51% Commercial & Industrial 49% Aerospace 2012 Sales: $57.7 billion Lean more at Pratt & Whitney 24% This page contains no technical data subject to the EAR or the ITAR. Sikorsky 12% Otis 21% UTC Climate, Controls, & Security 29% UTC Aerospace Systems 14% 2

3 UTRC...UTC s Innovation Engine Defining what s next Define new frontiers... AIS Autonomous & intelligent systems Co-develop new technologies... HPC ATOM High Additive Performance Topology Computing Optimized Manufacturing Otis Gen2 coated Next Gen steel belt centrifugal compressor compute power Solve tough problems... Materials characterization Surface topology and wear analysis Measurement science Digital imaging strain analysis Failure analysis Scattering to measure residual stress Serve as hub for technical interchange... Leverage global network of innovation... Tech scouting Crowdsourcing Rare Earth Magnets REM workshops This page contains no technical data subject to the EAR or the ITAR. 3

4 Technology Readiness Level, TRL NOT SUBJECT TO THE EAR PER 15 CFR Part 734.3(b)(3) Image Credit: NASA / Maria Werries 4

5 UTC Standard Work for Tribology Test Methodology & Characterization Metallurgical Evaluation & Characterization TRL 2 Laboratory & Elemental Testing TRL 3 Sub-scale Rig Testing TRL 4 Full-scale Testing TRL 5 System Test Full-scale Components TRL 6 Field Trial, Cert. & Flight TRL 7 & 8 Define new frontiers... Co-develop new technologies... Tribology TRL Characterization $$ Specimen Testing under standard test conditions $ Ranking of Material Pairs ONLY Specialized Specimen Testing under System Relevant conditions. $$ Generate Data relevant to DESIGN. 1. Wear rates 2. Wear limits 3. Etc. Full-scale Component testing under System Relevant Conditions. $$$ Endurance Testing Thermal Mapping, Wear & Skid Wear Failure Progression Margin testing Etc. This page contains no technical data subject to the EAR or the ITAR.

6 Tribology issues can result in significant setbacks! Significant cost and delays can occur if tribology issues are not properly considered and managed with proper tools during the development. Grounded aircraft fleets Early replacement of components Unrelated costs, if you open an engine to replace a $20 pin you might spend $N00k in additional work, consumables etc. Customer Job Ticket. Design for performance TRL 1 to 4 TRL 6 to 7 OMG!! We have a WEAR Problem Problem Resolved. Move on. Not our favorite things to do.. WEAR Resolution: Cost, schedule, and customer dis-satisfaction Solve tough problems... This page contains no technical data subject to the EAR or the ITAR. 6

7 Following a project through the TRL process, Bearings for active rotors Metallurgical Evaluation & Characterization TRL 2 Laboratory & Elemental WEAR Testing TRL 3 Sub-scale system relevant Testing TRL 4 Full-scale subsystem Testing TRL 5 System Test Full-scale Components TRL 6 Bearing spin rig Sub scale spin test Full scale blade section spin test Full scale rotor test in NASA-AMES 80x40 ft wind tunnel Double row ACBB Electromechanical actuator Blade section with full actuation Complete rotor This page contains no technical data subject to the EAR or the ITAR.

8 UTC Std Work for Material Wear Test Methodology & Characterization Metallurgical Evaluation & Characterization TRL 2 Laboratory & Elemental Testing TRL 3 Sub-scale Rig Testing TRL 4 Full-scale Testing TRL 5 System Test Full-scale Components TRL 6 Field Trial, Cert. & Flight TRL 7 & 8 WEAR TRL Characterization $$ Specimen Testing under standard test conditions $ Ranking of Material Pairs ONLY Specialized Specimen Testing under System Relevant conditions. $$ Generate wear Data relevant to DESIGN. 1. Wear rates 2. Wear limits 3. Etc. Full-scale Component Testing under System Relevant Conditions. $$$ Endurance Testing Thermal Mapping, Wear & Skid Wear Failure Progression Margin testing Etc. TRL 4 is where the biggest opportunity is! This page contains no technical data subject to the EAR or the ITAR.

9 TRL 4 Example: Testing under system relevant conditions Synergistic Link between Aerospace System Component CONTACT TRIBOLOGY Sliding velocity Design: Cylinder and Piston Materials: Through hardened AISI 440C Stainless Steel Lubricant: Kerosene or Hydraulic Fluid NOT SUBJECT TO THE EAR PER 15 CFR Part 734.3(b)(3) By Courtesy of David Haluck, P&W, AISI 440C/440C Stainless Steel Tribological Performance in Kerosene and Hydraulic Fluids Presented at the 15th. International Conference on Experimental Mechanics. Porto/Portugal, July 2012 by Herbert Chin1 David Haluck1, Matthew Disselkoen2, & William Black

10 Objective of Study and Technical Approach AISI 440C/440C Stainless Steel Tribological Performance in Kerosene & Hydraulic Fluids Objective: Determine sensitivity of corrosion resistant martensitic stainless steel, AISI 440C, to adhesive wear in kerosene and hydraulic fluid under aerospace actuator system relevant conditions. Technical Approach: Develop test machine and test protocol that replicates adhesive wear observed in aerospace actuators 1. Test Machine: Configure a test machine and specimen to conduct Tribological Testing that mimic & bounds the Actuator Operating conditions. 2. Test Protocol: Define and conduct a test protocol that covers the actuator operating range and challenges the response to the material/fluid couple NOT SUBJECT TO THE EAR PER 15 CFR Part 734.3(b)(3)

11 Test Method and Set-up Fretting motion: +/ at 200 Hz Two motions may be used simultaneously or separately. Normal Load Lubricant Reservoir Translational motion: +/-.250 at 2 Hz Specimen Contact Area Plate Specimen Grooved Specimen NOT SUBJECT TO THE EAR PER 15 CFR Part 734.3(b)(3) Mentor, Grand Master of Tribology Testing in System Relevant conditions, Vern Wedeven,

12 Value of testing under system relevant conditions! Test #: 29a Grooved Speicmen: #24 (56 HRC) Plate Specimen: #24 (60 HRC) Lubricant: Mixed Fluid Lubricant Condition: Submerged Normal Load: Increasing, 20 lb per cycle Frequency: Translation at 2 Hz, Fretting at 200 Hz Debris: Al2O Friction Coefficient Normal Load (lb) 250 Translational + Fretting Friction Coefficient Normal Load (lb) Normal load, lb Test #: 28a Grooved Speicmen: #23 (56 HRC) Plate Specimen: #23 (60 HRC) Lubricant: Mixed Fluid Lubricant Condition: Submerged Normal Load: Increasing, 20 lbs per cycle Frequency: Translation at 2 Hz Debris: Al2O Normal Load (lb) 250 Translational Only Friction Coefficient Friction coefficient Run Time (min) Friction Coefficient Normal Load (lb) Run Time (min) Plate Specimen Run time, minutes NOT SUBJECT TO THE EAR PER 15 CFR Part 734.3(b)(3) 12 of 15

13 Example: M50NiL, Its never as easy as one think Synergistic Link between Aerospace System Component Processing Tribology Design: Materials: Lubricant: TRIBOLOGY: Inner Ring Piloted CAGE Case hardened M50NiL Ring Silver plated steel CAGE Aerospace turbine oil Sliding contact & abrasive contaminants in the lubricant NOT SUBJECT TO THE EAR PER 15 CFR Part 734.3(b)(3) By Courtesy of David Haluck, Presented at : 15 th International Conference on Experimental Mechanics. Porto/Portugal, July 2012by David A. Haluck 1, Herbert A. Chin 1 and William Black 2 1 UTC-Pratt & Whitney, Materials & Processes Engineering, East Hartford, CT USA. 2 Wedeven Associates, Inc., Edgemont, PA USA

14 M50 is great but not all that tough. Aerospace Bearing Challenges & Steel Options Bearing Speeds > 2 million DN*, any spall event in through hardened steels, like AISI M50 can lead to sudden and catastrophic ring fractures. Case hardened fracture tough core bearing steel AISI M50NiL was developed to solve this and gave better RCF performance as bonus. Remnants of a Through Hardened Bearing Inner Ring Photo courtesy of Pratt & Whitney *DN defined as (bore dia., mm x rpm) NOT SUBJECT TO THE EAR PER 15 CFR Part 734.3(b)(3)

15 Lets fix it! M50NiL takes care of it! Tougher than nails! M50NiL is the answer to tougher rings. On top of that it has better fatigue properties due to better micro structure! M50 Steel (AMS 6490) Composition: Fe-0.81C-4Cr-4.25Mo-1V Through hardened (martensitic) steel. Hardness: 64 Rc (800 Hv) Fracture toughness ~ 25 MPa. m. Microstructure: Large carbides + fine secondary hardened M 2 C & M 3 C carbides dispersed in a high carbon tempered martensite matrix M50NiL Steel (AMS 6278) Composition: Fe-0.13C-4.1Cr-4.2Mo-1.2V-3.4Ni+MnSi CASE hardened (martensitic) steel. Hardness: Case = 64 Rc. Core = 48 Rc Fracture toughness, core >40 MPa. m. Microstructure: Case: high carbon (<1%) tempered martensite + Uniform fine carbide dispersion Core: low carbon tempered martensite Carburized case Steel core NOT SUBJECT TO THE EAR PER 15 CFR Part 734.3(b)(3)

16 What About The Cage-Ring Sliding Contact Bearings using M50 ring lands have experienced cage land wear when exposed to abrasive contaminants. Wear to inner ring land has occurred. Outer Race Will M50NiL with finer carbides it be resistant to abrasive contaminants? Inner Race Abrasive contaminants, embedded in cage land Inner ring cage land wear NOT SUBJECT TO THE EAR PER 15 CFR Part 734.3(b)(3)

17 Test Method, Set-up and Test Protocol Objective: Compare the wear resistance of M50NiL to M50 when exposed to contaminants in system relevant test conditions and environments. Contact stress Outer ring Contact stress Split inner ring Silver coated 4340 steel specimen Oil drip feed with Al 2 O 3 abrasive Vel: 3.3 m/s (1800 rpm) Load: 17.7 N (4 lbs) Cylinder NOT SUBJECT TO THE EAR PER 15 CFR Part 734.3(b)(3)

18 Results: M50 versus M50NiL with Al2O3 contaminant M50 steel: Abrasive causes plowing and results in a roughened surface M50NiL steel: Abrasive causes cutting and results in grooved surface and material removed Large carbides in steel disrupt cutting action. Fine carbides in steel do not resist cutting action NOT SUBJECT TO THE EAR PER 15 CFR Part 734.3(b)(3) Page 18 of 15

19 M50NiL Abrasive Wear Resistance Large Carbides in Martensitic Steels can (a) reduce RCF Life but (b) increases Abrasive Wear Resistance Stress concentration effect of large carbide particle Abrasive Wear Large Carbide resists abrasive cutting Material capability Equiv. Stress Fine carbide structure Distance from surface Finer Carbides in M50NiL Steel Coarser Carbides in M50 Steel NOT SUBJECT TO THE EAR PER 15 CFR Part 734.3(b)(3)

20 Solution! Lets TiN coat the land guiding the cage! Results for TiN coated M50NiL steel and Al 2 O 3 debris: Minimal wear & fine scratches observed on TiN surface Titanium Nitride (TiN) coated steel specimen Edge of wear track Abrasive wear scratches NOT SUBJECT TO THE EAR PER 15 CFR Part 734.3(b)(3)

21 M50NiL Abrasive Wear Resistance Summary of Test Cylinder Wear Results 12 micron Al 2 O 3 M50NiL M50 12 micron Al 2 O 3 12 micron Al 2 O 3 M50 NiL + TiN Coating NOT SUBJECT TO THE EAR PER 15 CFR Part 734.3(b)(3)

22 Ok, Lets validate RCF properties Wait a minute.. What's up with the legends, M50NiL is better, right? Local delamination of the TiN coating caused premature fatigue in the M50NiL.. NOT SUBJECT TO THE EAR PER 15 CFR Part 734.3(b)(3)

23 THANK YOU FOR LISTENING! This page contains no technical data subject to the EAR or the ITAR.