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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society of Tribologists and Lubrication Engineers
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The Korean Society of Tribologists and Lubrication Engineers
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Volume & Issues
Volume 18, Issue 6 - Dec 2002
Volume 18, Issue 5 - Oct 2002
Volume 18, Issue 4 - Aug 2002
Volume 18, Issue 3 - Jun 2002
Volume 18, Issue 2 - Apr 2002
Volume 18, Issue 1 - Feb 2002
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A Study on Design Parameters to Improve Load Capacity of Spiral Grooved Thrust Bearing
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 18, issue 3, 2002, Pages 181~186
A numerical analysis is undertaken to show the influence of bearing design parameters on the load capacity of air lubricated spiral grooved thrust bearing. The governing equation derived from the mass balance is solved by the finite difference method. Optimal values for various design parameters are obtained to maximize the load capacity. The design parameters are the groove angle, the groove width ratio, the groove height ratio, and the seal ratio.
Discussion on Hardness Measuring of Bearing Steel by X-ray Diffraction
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 18, issue 3, 2002, Pages 187~193
The half-value breadth off-ray diffraction profile line is generally used for a factor in nondestructive hardness measuring method of steel. In this paper, the problem in using the half-value breadth for the hardness measuring method is evaluated in strain hardened steel. And new hardness measuring method using residual stress is proposed X-ray diffraction test after rolling contact fatigue test of ball bearing with inner race of various hardness are carried out to measure the distribution of residual stress and half-value breadth from surface. The result of this study shows that there is little correlation between half-value breadth and hardness in the higher strength region and in the region increasing the hardness by strain hardening. But the magnitude of residual stress on/under race after rolling contact fatigue test becomes clearly to be correlative with hardness. Thus, it is concluded that the hardness of strain hardened steel can be estimated by this relationship between residual stress and hardness.
The Development of Partial Model for Thermo-Mechanical Stress Analyses of Part with Coated Layer under Contact Load
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 18, issue 3, 2002, Pages 194~203
This paper is the first step fur thermo-mechanical stress analyses of part with coated layer under contact load. A lot of coated material is applied in many structures to endure severe situation, like thermal stresses, high temperature gradients, irradiation, impacts by microscopic meteorites, and so on. In this part we are going to apply the FEM to analyze space parts with a coated layer subjected to a contact load thermo-mechanically. Coating layer is very thin in comparision with the structure, therefore it should take more times and behaviors to analyze whole model. In these reason we develop the FEM method of analyzing part with coated layer under contact load using partial model. Steady state temperature distribution of the part is obtained first, and then we apply quasi-static external load on the part. To obtain the final stage of solution, we compute the total solution, and by subtracting the thermal strain from the total ones we get the mechanical strains to compute stresses of the parts. In using the FEM, one has to discretize the model into many sub-domain, finite elements. The method is consisited of two steps. First step is to analyze the whole model with rather coarse meshes. Second step we cut a small region near the loading point, and analyze with very fine meshes. This method is allowable by the Saint-Venant's principle. And then, we finally shall check the therma1 load on the stresses of the space part with coating layer with or without substrate cracks. Then, we predict the actual behaviors of the part used in space.
Tribological Behavior of Automotive Brake Pads with Different Sizes of zircon Particles
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 18, issue 3, 2002, Pages 204~210
Automotive brake pads with four different sizes of zircon particles (average sizes of 1㎛, 6㎛, 75㎛, and 140㎛, respectively) were investigated to evaluate the size effect of abrasive particles on friction performance. Results showed that the brake pads with the larger size of zircon particles tend to show better frictional stability and low pad wear. However, the rotor surface was severely abraded in the case of using larger zircon particles. On the other hand, the small zircon particles in the pads showed the fast increase of the coefficient of friction with friction force oscillation and the tendency was pronounced at low sliding speeds. The brake pads with small particle sizes also exhibited strong fade phenomena at elevated temperatures.
The Effect of Finished Surface Orientation on Friction Characteristics in Boudary Lubrication
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 18, issue 3, 2002, Pages 211~218
The effect of characteristic of surface roughness and roughness patterns on friction was studied experimentally in boundary lubrication with reciprocating tribometer. Roughness was changed from Ra=0.2(
). Three roughness pattern-transverse, oblique, longitudinal- were tested for various load and velocity. The experimental results show that the scuffing resistance of surfaces with transversal roughness pattern is higher than that of surface with longitudinal and obliq pattern. under the conditions of the roughness values of Ra=0.2, 0.5,1.0 and 1.2. surfacer roughness (Ra) was decreased with the normal load increased before scuffing occurred. oblique pattern and longitudinal pattern with Ra=0.2 and Ra=1.0 was higher scuffing load under low sliding velocity, but with Ra=0.5 was higher scuffing load under high sliding velocity.
Thermoelastic Finite Element Analysis of Double horizontal Subsurface Cracks Due to Sliding Surface Traction
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 18, issue 3, 2002, Pages 219~227
A linear elastic fracture mechanics analysis of double subsurface cracks propagation in a half-space subjected to moving thermomechanical surface traction was performed using the finite element method. The effect of frictional heat at the sliding surface on the crack growth behavior is analyzed in terms of the thermal load and peclet number. The crack propagation direction is predicted in light of the magnitudes of the maximum shear and tensile stress intensity factor ranges. When moving thermomechanical surface traction exists, subsurface horizontal cracks are propagation in-plane crack growth rate at the beginning but they are propagation out-of-plane crack growth rate by the frictional heat which is occurrence by the repeated sliding contact.
Thermo-Mechanica1 Stress Analyses of Part with Coated Layer under Contact Load Using Partial Model
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 18, issue 3, 2002, Pages 228~234
Generally, space structures are subjected to severe situations, such as, sublimation, strong evaporation of lubricants, thermal stresses, high temperature gradients, irradiation, impacts by microscopic meteorites, and other factors. Recent]y, various kinds of coatings are applied to the parts under heavy contact stresses, in order to insure long wear-free lives and/or reduce friction coefficients. In space structures, molybdenum disulfide is using frequently. Moreover TiN, Al
, PTFE(Poly Tetra Fluor Ethylene) are introduced recently for space structure. In this part we are going to apply the partial model method, developed in reference to analyze part with coated layer. In referencer[l1], we compute the reasonable size of partial model and aspect ratio. Using these data, we analyze the structures coated with TiN, Al
, PTFE under contact load, temperature and crack model . Beside, we consider the stress analysis under time dependent load and transient thermal effect.