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[論文] 鋼材의 衝擊疲勞破壞壽命에 미치는 Tempering 效果에 관한 硏究
정재천(Chae-Cheon Cheong) 한국자동차공학회 1981 오토저널 Vol.3 No.3
The fatigue characteristics of Si-Mn spring steel (AISI'9260-H, JIS SUP-6) were investigated on several heat treatment conditions, Repeated impact loads of 10kg-cm and 15kg-cm energy were applied with a cam roller drop hammer type impact fatigue testing machine.<br/> Specimens were oil-quenched, and tempered at 350℃, 400℃, 450℃ and 500℃, respectively. Results obtained in these experiments are summerized as follows. :<br/> 1) The fatigue life of the specimen is decreased as the magnitude of constant impact energy is increased, regardless of heat treatment.<br/> 2) Generally, the fatigue life of the specimn is decreased as the tensile strength of the materials is increased.<br/> 3) Within the limit of these experiments, the fatigue life showed abrupt decrease at the tempering temperature of about 400℃.<br/> 4) The fatigue life is increased as the initial value of applied stress intensity factor (K₁) is decreased. This tendency is apparent for the low tensile strength materials.
ER 유체와 압전 작동기를 이용한 엔진마운트의 모델구성 및 성능해석
최승훈(Seung-Hoon Choi),최승복(Seung-Bok Choi),정재천(Chae-Cheon Cheong) 한국자동차공학회 1994 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This paper presents a new prototype of an engine mount for a passenger vehicle featuring ER(electro-rheological) fluids and piezoelectric actuators. A mathematical model of the proposed engine mount is derived using the bond graph method which is inherently adequate to model the interconnected hydro-mechanical system. In the low frequency domain, the ER fluid is activated upon imposing electric field for vibration isolation while the piezoactuator is employed in the high frequency domain. On-off control algorithm is formulated for the ER fluid, and the H_∞ control technique is adopted for the piezoactuator. Computer simulation is undertaken in order to demonstrate the isolation effect of the engine mount over wide operating frequency range.<br/>