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윤활유의 수분혼입 및 베어링강의 표면 조도가 구름접촉 피로수명에 미치는 효과
허태현 ( Tae Hyeon Heo ),심충기 ( Chung-ki Sim ),김홍석 ( Hong Seok Kim ),신기훈 ( Ki-hoon Shin ),정성균 ( Seong Kyun Cheong ) 한국안전학회(구 한국산업안전학회) 2017 한국안전학회지 Vol.32 No.1
A large amount of research has been performed on the rolling contact fatigue(RCF) life of bearings, since it directly affects the safety and reliability of mechanical systems. It is well known that rolling contact fatigue life is influenced by several parameters including contact pressure, oil contamination by water or metal particles, and the surface conditions of bearings. However, the detailed damage mechanisms involved in rolling contact fatigue have not been clearly identified yet. In this paper the effects of water contamination of the lubricant and surface roughness of bearing steel on the rolling contact fatigue life were investigated. Two types of specimens with different surface roughness values were prepared through turning and lapping operations. They were tested under two different lubrication conditions, i.e. oil lubricant with 100% of oil and the water contaminated condition with 80% of oil and 20% of water using the rolling contact fatigue testing machine. The surface damage induced by the rolling contact fatigue was observed by using atomic force microscope(AFM). Experimental results show that the rolling contact fatigue life, L<sub>10</sub> was reduced by 24 to 33% depending on the lubrication condition. The reduction of fatigue life in the range of 53 to 57% was also observed at different surface roughness conditions.
김정석(Kim Jung Seok),이재헌(Lee Jae Hun),정성균(Chung Seong Kyun),김승철(Kim Seung Chul),서승일(Seo Sung Il) 한국철도학회 2007 한국철도학회 학술발표대회논문집 Vol.- No.-
This paper explains compressive behaviors of sandwich composite laminates with adhesively bonded patches. The sandwich composite laminate is used for a train carbody structure and is of an aluminum honeycomb core and CF1263 woven fabric carbon/epoxy faces. The sandwich composite laminates were damaged by low velocity impact. The damaged sandwich composite laminate was repaired using scarf repair method. Then, the strength restoration of it was assessed by compressive test. From the test, it could be known that the compressive strength was restored up to 91% of undamaged one.
정성균,정동건,박충식,김태형,이재헌 서울産業大學校 2002 논문집 Vol.53 No.1
In this paper, the effect of shot peening on the fatigue characteristics have been investigated. Two types of specimens were used to obtain the experimental results. One type of specimen was made by machining and heat-treating SCM415 steel. The other type of specimen was made by machining, heat-treating, and shot peening SCM415 steel. The hydraulic testing machine was used to do the fatigue test (R=0.1, 10Hz). The experimental results show that the fatigue life and strength of shot peened gear were largely improved compared with the unpeened gear.