http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Boundary Lubrication in Transient Elliptical Contact: Part 1- Theoretical Formulation and Results
Di-Chu Xu,Qi Zhang,Jiu-Gen Wang 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.4
The transient elliptical contacts in boundary lubrication widely exist in modern mechanical systems with high durability. However, little attention has been paid to the squeeze effect of fluid film in this condition. A deterministic model which combines the contact mechanics with the pure squeeze lubrication model has been developed with the aim of understanding the squeeze effect of fluid film under the transient boundary lubrication. The leakage coefficient was introduced to capture the fluid leakage of rough surfaces. The squeeze effect of trapped fluid film was confirmed through comparing the fluid film stiffness in boundary lubrication with that of the elastohydrodynamic lubrication. Additionally, the effects of fluid film entrapment/leakage on the boundary lubrication performance were numerically analyzed during transients. The load capacity of the squeeze films is built up due to the trapped fluid film in the micro-valleys, which can be significantly affected by the interfacial shear coefficient of the boundary films. The simulation results show a good agreement with the experiments and justify the present numerical model is feasible in the boundary lubrication regime.
Transient Elastohydrodynamic Lubrication Film Thickness in Sliding and Rolling Line Contacts
Siyoul Jang 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.5
The contact behavior between cam and follower is greatly influenced by the kinematics and dynamics of the whole valve train system. This is the reason that both shape and thickness of the fluid film in the contact gap are mainly determined by applied loads and relative contact speeds as well as the curvatures of contacting elements. Most of the studies about lubricant film behavior between cam and follower have been performed without a consideration of transient effects in the contact gap. For the computational difficulties of transient effects, most contact conditions such as relative contacting speeds have been regarded as quasi-steady state during the whole operating cycle. In this work, in order to obtain stable convergence, a multigrid multi-level method is used for the computation of load capacity in the lubricant film. Nonlinear valve spring dynamics are also considered in the same way as Hanachi’s. From the computational results, transient EHL film thicknesses under the conditions of different contact geometries are computed for a pushrod type valve train system during an engine cycle. Several results show the squeeze film effect, which is generally not found with conventional EHL computations of the cam and follower contact. The results are also compared with those by the Dowson-Hamrock (D-H) formula, which does not consider the dynamic film effect. Without the dynamic film effect as in D-H’s formula, the minimum film thickness is highly dependent on the entraining lubricant velocity, whereas the minimum film thickness including the squeeze film effect is dependent on the applied loa
Design of an Haptic Tactile Interface (HTI) with Friction Coefficient Measurements
Winter, Christophe,Perriard, Yves Journal of International Conference on Electrical 2013 Journal of international Conference on Electrical Vol.2 No.4
An haptic tactile interface (HTI) is presented with its modeling. Its design is dedicated to perform friction coefficient measurement to characterize reachable feelings with that kind of interface. Friction measurements are presented and discussed.
장시열(Siyoul Jang),임홍재(Hong Jae Yim),강윤석(Yun Seok Kang) 한국트라이볼로지학회 2006 한국트라이볼로지학회 학술대회 Vol.2006 No.6
Surface contacts between mold and target should be in parallel for the imprinting mechanism. However, the size of contacting area makes it difficult for both mating surfaces to be in all contact because of precision level of the imprinting machine and the waviness of mold and target. The gripping force for both mold and target with the vacuum chuck is also major effect to interrupt the full contact, which must be avoided in imprinting mechanism. In this study, the preliminary study for the causes of non-uniformity of contacting surfaces such as mold and target is performed with 470 × 370㎟ LCD panel size.
진공척 흡착패드 형태에 따른 대면적 임프린팅 균일 접촉 향상 연구
장시열(Siyoul Jang) 한국트라이볼로지학회 2008 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.24 No.6
The contact surfaces between mold and target should be in parallel for a proper imprinting process. However, large size of contacting area makes it difficult for both mating surfaces (mold and target planes) to be in all uniform contact with the expected precision level in terms of thickness and position. This is caused by the waviness of mold and target although it is very small relative to the area scale. The gripping force for both mold and target by the vacuum chuck is other major effect to interrupt the uniform contact, which must be avoided in imprinting mechanism. In this study, the cause of non-conformal contact mechanism between mold and target is investigated with the consideration of deformation due to the vacuum gripping for the size 470×370㎟ LCD panel.