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Hydraulic Engine Mount(HEM)의 동강성이 샤시진동에 미치는 영향
유완석,강동권,김명규 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.6_2
Hydraulic Engine Mount(HEM) are replacing rubber mounts to get better ride quality and to reduce engine vibration. The stiffness of a HEM is consisted of two portions, i.e., the hydraulic stiffness K_e from fluid and the structural stiffness Km from rubber containing the fluid. In this paper, effects of HEM parameters on ride quality are investigated by changing the values Kt, crosssectional area of orifice A_o and fluid mass in the orifice m. Eighteen cases are compared and an optimum value for a quarter car is proposed.<br/>
SUGGESTION OF MSTV (MODIFIED-STICK-TRANSITION-VELOCITY) MODEL FOR HYSTERETIC DAMPING MECHANISM
유완석,Jae-Cheol Lyu,Gyung-Hun Nho,Bo-Sun Chung,Jeong-Han Lee,Sung-Woon Jung 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.7
To decrease vibration and noise in washing machines, lubricated friction dampers were installed. Although the struc-ture of the friction damper is simple, it was not easy to develop a mathematical model for the dynamic behavior of the lubrication damper. To see the dynamic behavior of a friction damper, physical tests were carried out via a material testing machine by changing exciting amplitudes and frequencies. Complicated curves of spring characteristics and damping showed a hysteretic behavior. In this paper, a reasonable model for a friction damper is suggested. To model iction model was first applied. To get a refined model for stick and transition, an STV (stick transition velocity) model was analyzed. To develop a more accurate mathematical model, an MSTV (modified stick transition velocity) model was proposed. In the MSTV model, the friction force could be changed due to the velocity of the damper, and the damping force was calculated according to the relative velocity between the external displacement and the deformation of the sponge in the friction damper. The MSTV model was in a good agreement with the experimental results. Keywords
Relationship between subjective and objective evaluations of steering wheel vibration
유완석,Sang-Do Na,김민석 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.7
Two passenger cars were driven at several speeds over several road profiles to evaluate the subjective ratings of steering wheel vibration. A 3-axis translational accelerometer was mounted on the steering wheel to measure the acceleration signal transmitted to the hands. Correlations were determined between the measured accelerations and the subjective ratings of 4 expert drivers and 10 general drivers by using Stevens’ power law. The subjective ratings were found to be more highly correlated with the r.m.q. (root mean quad) values of the frequency-weighted acceleration than the r.m.s. (root mean square) values of the frequency-weighted acceleration. Also, the maximum values of r.m.q. (i.e., the component values in the dominant axis) had the highest correlation with the subjective ratings.