국내 최대 기계 및 로봇 연구정보

기술보고서

기술보고서 게시판 내용
타이틀	Advanced Gear Alloys for Ultra High Strength Applications
저자	Shen, Tony;; Krantz, Timothy;; Sebastian, Jason
Keyword	BENDING FATIGUE;; COMPRESSION LOADS;; FAILURE ANALYSIS;; FATIGUE TESTS;; GEARS;; HARDNESS;; HIGH STRENGTH;; MICROMECHANICS;; PITTING;; RESIDUAL STRESS;; STEELS;; TRANSMISSIONS (MACHINE ELEMENTS)
URL	http://hdl.handle.net/2060/20110023751
보고서번호	NASA/TM-2011-217121
발행년도	2011
출처	NTRS (NASA Technical Report Server)
ABSTRACT	Single tooth bending fatigue (STBF) test data of UHS Ferrium C61 and C64 alloys are presented in comparison with historical test data of conventional gear steels 񣻞 and Pyrowear 53) with comparable statistical analysis methods. Pitting and scoring tests of C61 and C64 are works in progress. Boeing statistical analysis of STBF test data for the four gear steels (C61, C64, 9310 and Pyrowear 53) indicates that the UHS grades exhibit increases in fatigue strength in the low cycle fatigue (LCF) regime. In the high cycle fatigue (HCF) regime, the UHS steels exhibit better mean fatigue strength endurance limit behavior (particularly as compared to Pyrowear 53). However, due to considerable scatter in the UHS test data, the anticipated overall benefits of the UHS grades in bending fatigue have not been fully demonstrated. Based on all the test data and on Boeing s analysis, C61 has been selected by Boeing as the gear steel for the final ERDS demonstrator test gearboxes. In terms of potential follow-up work, detailed physics-based, micromechanical analysis and modeling of the fatigue data would allow for a better understanding of the causes of the experimental scatter, and of the transition from high-stress LCF (surface-dominated) to low-stress HCF (subsurface-dominated) fatigue failure. Additional STBF test data and failure analysis work, particularly in the HCF regime and around the endurance limit stress, could allow for better statistical confidence and could reduce the observed effects of experimental test scatter. Finally, the need for further optimization of the residual compressive stress profiles of the UHS steels (resulting from carburization and peening) is noted, particularly for the case of the higher hardness C64 material.