• Journal of Advanced Marine Engineering and Technology
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• 제16권1호
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• pp.27-34
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• 1992

In eliminating the nonlinear characteristics such as piston displacement dift and difference in speeds of the reciprocating motion due to their nonsymetrical structure of single rod cylinder, the linear model can be given by equivalent outside disturbance, etc. The position control method of single rod cylinder servosystem using the sliding mode control of VSS was suggested and the good results without off-set are compared with PD control of fixed structure system.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.173-174
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• 2002

To study the effects of mating materials on the tribological properties of DLC films. we used a ball-on-plate reciprocating friction tester in dry air and mating materials of martensite stainless steel (hardened, annealed SUS440C), austenite stainless steels (SUS304), and bearing steel (hardened, annealed SUJ2). At a light load of 0.6 N, the friction coefficient always exceeded ${\mu}>0.3$. Tribological properties of DLC film were still excellent above 0.6 N, except in sliding against annealed SUJ2. Analysis using micro-laser Raman spectroscopy showed that the difference between annealed SUJ2 and others materials appears mainly due to structural change in film.

• KSTLE International Journal
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• 제2권1호
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• pp.55-58
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• 2001

The most widely-used orthopaedic grade polymer bearing liner material, ultrahigh molecular weight polyethylene (UHMWPE), for the total joint arthroplasty degrades after gamma-irradiation sterilization through the progressive oxidation in a shelf and in vivo. Oxidative degradation makes UHMWPE brittle and leads to decrease in mechanical properties. In this study the relationship between post-gamma-irradiation aging time and wear of UHMWPE was investigated. Six retrieved polyethylene hip liners implanted for 3-16 years and then stored in air for 1.5-6.5 years until tests were used. Two types of pin-on-disk wear testing were conducted by the uni-directional repeat pass rotating and by the linear reciprocating stainless steel disks against stationary polyethylene pins under 4Mpa at 1Hz with bovine serum lubrication in ambient environment. Wear of retrieved polyethylene hip liners does not have direct correlation with in vivo or total aging time. Linear reciprocal sliding motion generated more remarkable wear than uni-directional repeat pass sliding motion. It indicates that kinematic motion affects very crucially on the wear of aged UHMWPE having brittle white band region.

• Tribology and Lubricants
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• 제18권3호
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• pp.211-218
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• 2002

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($\mu\textrm{m}$)to Ra=1.2($\mu\textrm{m}$). 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.

• Tribology and Lubricants
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• 제25권2호
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• pp.114-119
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• 2009

Fretting occurs wherever short amplitude reciprocating sliding between contacting surfaces is sustained for a large number of cycles. The fundamental characteristic of fretting is the very small amplitude of sliding and combination of different wear mechanism. Predicting wear is important to enhance reliability of the parts. The objective of this paper is to predict fretting wear by using a contact analysis considering wear process. This construction will give us important information to know a property of fretting wear.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.367-373
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• 2001

The effect of characteristic of surface roughness and roughness patterns on friction and sliding wear was studied experimentally under reciprocating boundary lubricant sliding conditions. The test was conducted with specimens which have various arithmetic mean value and roughness pattern under the condition of different normal load. The experimental results show that the friction coefficient is decreased because of oxidation mass and valley effect as the normal loads increasing It was found that the specimens with surface roughness with a transverally oriented pattern have a smaller firction coefficient than the other two roughness patterns under the condition of the roughness values of Ra=0.5 and Ra=0.2 .

• Tribology and Lubricants
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• 제13권2호
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• pp.89-95
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• 1997

This paper considers two dimensional analysis for lubrication between the single piston ring and the cylinder liner. The piston ring is treated as a reciprocating, hydrodynamic bearing with combined sliding and squeeze motion. Reynolds' equation is used, to model lubrication with Reynolds' cavitation boundary condition. This analysis is developed to get the cyclic variation of minimum film thickness and viscous frictional force. Two types of piston ring face shape are considered. This result can be used to study the influence of ring shape design parameter to improve the characteristics of sealing and lubrication.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제34회 추계학술대회 개최
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• pp.19-26
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• 2001

The wear characteristic of Zircaloy-4 tube, which is used for a cladding of light water reactor fuel rod, is investigated experimentally. The experiment is conducted with contacting the crossed tube specimens in air as well as in water at room temperature with various combination of contact normal force and sliding distance of reciprocating motion. The contour and the volume of each wear are examined to study the effect of contact condition and environment on wear. As a result, it is found that the wear volume in the water environment is larger than that in the air for all the contact (i.e., force and sliding distance) conditions. However, the wear depth is greater in air than in water if the contact normal force and the sliding distance are larger. These are explained by the ease of detachment of wear particles from the contact surface. On the other hand, workrate model is applied with the contact shear force range measured by our wear tester. Investigated is the correlation between the workrate and the wear volume increase rate of the present experiment. The parabolic curve is found to fit well for the present wear data.

• 한국추진공학회지
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• 제18권4호
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• pp.67-73
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• 2014

고온고압의 밸브에서 연소가스의 유입을 방지하는 흑연 씰은 밸브 축의 구동으로 인한 마찰 및 마모에 노출된다. 흑연 씰의 마모로 인해 고온 가스 제어가 불가능해지기 때문에 씰의 마모 특성을 예측하는 것은 매우 중요하다. 본 논문은 비마모율을 마모 특성에 대한 척도로 설정하고 접촉하중, 미끄럼 속도, 온도 등을 변수로 하여 흑연의 왕복동 마모 시험을 수행하였다. 반응표면분석법에 근거하여 실험계획을 정립하고 시험 결과에 대하여 분산분석법을 통하여 유효한 수학적 모델을 제시하였다. 또한, 마모된 표면의 SEM 분석을 통해 특정 조건에서의 마모 메커니즘을 분석하고 비교하였다.

• Tribology and Lubricants
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• 제35권6호
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• pp.337-342
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• 2019

This paper presents an experimental investigation of friction and wear characteristic with respect to patterns occurring on the surface of 3D printed polymer products by fused deposition modeling method. The purpose of this study was to investigate the effect of the patterns and sliding directions on the tribological properties of 3D printed polymer surface. A cubic specimen was printed using polylactic acid filament as the printing material. Friction tests were conducted for different directions with respect to the patterns that were generated on the top and the side surfaces of the specimen, by using a ball-on-reciprocating type tribotester. SUJ2 bearing ball of which the diameter was 11 times greater than the width of the largest pattern was used as the counter surface to assess the frictional behavior. Friction tests were conducted on the top and the side surfaces with respect to the patterns in 3 (0°, 45°, 90°) different directions respectively. Coefficient of friction increased as cycles increased in all cases. The results of the tests showed that the lowest coefficient of friction was measured with the 45° sliding direction on the side surface. The wear rate was the lowest at 45° sliding direction on the side surface, while it was the highest at 0° sliding direction on the top surface. Coefficient of friction of about 0.45 was determined to be the converging value on the top compared to the side surface.