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브레이크 디스크의 잔류응력이 제동 시 떨림 현상에 미치는 영향
장국현(Gug Hyun Jang),장호(Ho Jang),김희열(Hee Yeol Kim),김정규(Jeong Kyu Kim) 한국트라이볼로지학회 2009 한국트라이볼로지학회 학술대회 Vol.2009 No.11
Residual stress of the grey iron brake disk was studied by neutron scattering. A vacuum heat treatment schedule was employed to compare the change of residual stress in three principal orientations (i.e., normal direction, radial direction, and hoop direction) before and after stress relaxation. Dimensional variation of the disks after the heat treatment was also measured using a static disk thickness measurement device. The result shows that the residual stress in the disk was decreased after the heat treatment and the relative amounts of stress relaxation were dissimilar in three principal orientations. Permanent disk distortion was observed after dynamometer tests that simulated hot judder during brake applications, confirming the effect of residual stress on hot judder phenomena. The root cause of the residual stress induced thermal distortion was also discussed by examining the high temperature tensile strength of grey iron up to 600℃.
황희정(Heejeong Hwang),장호(Jang Ho),이완규(Wan gu Lee),장국현(Gug hyun Jang) 한국트라이볼로지학회 2009 한국트라이볼로지학회 학술대회 Vol.2009 No.6
In this study, friction and wear of stainless steel was examined as functions of time, speed, load, and grinding fluids. Surface roughness and the friction coefficient were monitored during tribotests using a block-on-disk tester. The surface roughness of the steel after tests was strongly affected by the load and type of grinding fluid used during grinding. Results showed that the steel ground with mineral oil as grinding fluid showed high surface roughness while the coefficient of friction was lower than other cases. In this paper, the possible mechanism for this salient result is discussed, providing a possible methodology for improving corrosion resistance of the steel surface after grinding operation.