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정적압축하중 하에서 임플란트 시스템의 파손 및 파괴 거동
김경난(Kyung-Nan Kim),최광훈(Kwang-Hoon Choi),오환섭(Hawn-Sup Oh),박준봉(Joon-Bong Park),권긍록(Kung-Rock Kwon) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
Dental implant system have gotten treatment again, because failure of dental implant system frequently occurred during dental implant treatment or use. Therefore, the aim of this study was to evaluate causes of failure. So we investigated deformation behavior by using load-displacement curve of fixture-abutment combination, and failure mechanism of implant system about tightening torque. As a result, (1)deformation behavior under bending moment didn't combine a system of solid type in lower tightening torque. (2)Fracture of the tightening bolt started the root of the first thread by tensile plastic crack, and then compressive plastic crack occurred at the opposite side. After these two cracks grew, they should finally meet near the center. (3)Plastic crack should grow by Von-Mises stress in stress concentration zone more than by maximum stress in the root of thread.
김경난(Kyung-Nan Kim),최광훈(Kwang-Hoon Choi),오환섭(Hawn-Sup Oh) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
In this study, the problem of Fitness for Abutment and Fixture was to define Contact ratio and Contact area ratio as tightening torque and to evaluate by using load-displacement curve. As a result, (1)when tightening torque was 30Ncm, Contact ratio and Contact area ratio were 0.2~0.6 and 0.27 respectively. When tightening torque was 50Ncm, Contact ratio and Contact area ratio were 0.4~1.0 and 0.41 respectively. (2)When using load-displacement curves under bending moment to evaluate the tightening state, two deformation regions exist in 30Ncm, and in the case of 50Ncm, the implant system appears to have deformation behavior of solid type.
이종마찰압접재 압접계면의 잔류응력이 기계적 성질에 미치는 영향
최광훈(Kwang-Hoon Choi),김경난(Kyung-Nan Kim),오환섭(Hawn-Sup Oh) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
In this study, evaluated the strength behavior of the friction welded material of suh3 and suh35 that it normally used to made vehicle valve. Friction welding of dissimilar materials caused a difference of residual stress in the connection and it is possible to break the machine. To find out a influence of factor in the fracture, it is necessary to observe the plastic flow through the tensile test according to the variation in diameter and heat treatment, microstructure of welding interface and hardness test As a result, the specimens without heat treatment caused the fracture in the interface while the specimens which remove residual stress through heat treatment caused the fracture around interface. In short the residual stress in the interface is proved to be decisive factor to fracture. However plastic flow did not affect the broken.
최광훈(Choi Kwang Hoon),오환섭(Oh Hwan Sub),김경난(Kim Kyung Nan) 한국생산제조학회 2010 한국공작기계학회 추계학술대회논문집 Vol.2010 No.-
Electropolishing is used to improve mechanical properties such as surface roughness and corrosion resistance . In addition, It is used to remove deformed layer by machining process. In this study, Electropolishing behaviour of SUH35 has been evaluated in the acetic anhydride-percholic acid system. In order to success in the electropolishing, It is important to find the influence of parameter such as current density, electrode gap and electropolishing time, etc. As a result, there were three distinct regions of current density-voltage curve and good electropolished surface is obtained at plateau area(18V, 0.7A/㎠). Also It is possible to see optimum surface condition in the 3~7㎜ electrode gap and processing time over a period of time.