LOW-CYCLE FATIGUE AND ULTIMATE STRENGTH RELATED TO GEAR DESIGN.

This paper describes the development of a method for assessing the ultimate tensile and limit load strength values required by MIL-A-8860(ASG) for aircraft actuator gear teeth, and the subsequent effect of a few very-high-load cycles with regard to bending and surface fatigue life. American Gear Manufacturers Association (AGMA) rating procedures are found to require modification for pitch point contact, modulus of rupture, higher contact ratios, and the extension of S-N curves to one load cycle. These modified rating procedures, combined with qualifying statements, provide for relatively simple calculation. Background and application data are provided for gear teeth under relatively common load conditions that are not included in AGMA standards.