Follow this link to go to the text only version of nasa.gov
NASA - National Aeronautics and Space Administration
+ Contact NASA
Go
Structures and Materials Division Research and Technology Directorate NASA Glenn Research Center

Tribology and mechanical Components Branch
Tribology and mechanical Components Home
Research Areas
Facilities
Personnel
Publications
Computer Codes
Partner with Us
Contact Information
Aero Drive Systems - Gear Surface and Bending Fatigue
Research Objectives
The objective is to discover and validate methods to increase the power density of gears to allow for the lightest weight possible for a given application. This research area focuses on knowledge about the fatigue properties of gears. Research is directed towards two types of fatigue. Surface fatigue occurs on the contacting surface of the gear tooth profile. Bending fatigue occurs near the base of the gear tooth on the non-contacting region. Many aspects of this topic have been and continue to be studied including material composition and processing, gear geometry, lubrication technology, experimental assessments of fatigue life, stress analysis and fatigue theory, and statistical treatment of fatigue data.
Technical Challenges
  • Assessment of emerging research on new materials, steel alloying, material quality control and processing, control and manipulation of residual stress for application to gears
  • Testing of new technology to develop stress-cycle data for design and for comparison of competing technologies
  • Use of emerging surface engineering to enhance surface fatigue power density
Current Research
Gear Bending Fatigue Behavior Assessed
Low cycle fatigue behavior of AISI 9310 steel gears was established via single tooth bending fatigue testing and a recently developed alloy was tested and compared to the currently used AISI 9310 alloy. For more information refer to NASA research reports TM-2007-214914 and TM-2007-215009.

Gear bending fatigue data from two steel alloys

 
Above: Gear bending fatigue data from two steel alloys. The numbers in the left column indicate the "Bending Stress Index (GPa)" and the bottom numbers indicate the "Cycles to crack initiation".
 

Laboratory tool for gear tooth strains demonstrated
The capability to measure gear tooth strains during single tooth bending testing using a laser-based instrument was recently established.

Gear tooth under test
 
Above: Gear tooth under test
 
Measuring gear tooth strains
 
Above: Display of measured gear tooth strains as a crack begins to develop during gear durability testing.
 


+ Return to the branch research page...
Point of Contact
Dr. Tim Krantz
Publications
View a list of published NASA reports
+ View related publications
Related Facilities
Learn more about our Aero Drive Systems Facilities
+ View Facility Listing


MORE INFO IN NASA SITE NETWORK

+ Freedom of Information Act
+ NASA Web Privacy Policy and Important Notices
NASA - National Aeronautics and Space Administration
NASA Official: Ajay K. Misra
+ Web Curator
+ Contact NASA
Last Updated: April 21, 2009