• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 2000년도 제31회 춘계학술대회
• /
• pp.42-47
• /
• 2000

The friction and lubrication characteristics of joint cartilage were investigated using the metatarso-phalangeal joint cartilage of rabbit against rotating stainless steel disk. Friction tests were conducted by dry and bovine serum lubricated sliding at room and body temperatures. For the dry sliding tests, low friction coefficient of 0.1-0.15 was observed at the early period of test, and then the friction coefficient increased as a test continued. With increasing applied load the early period of low friction lengthens. For the lubricated sliding tests, the coefficient of friction decreased as the applied load increased. And also the coefficient of friction decreased continuously to 0.07 as the test duration increases. These results can be interpreted that the squeeze or weeping lubrication mechanism dominates the friction and lubrication characteristics in the joint cartilage of rabbit.

• Tribology and Lubricants
• /
• 제17권4호
• /
• pp.307-311
• /
• 2001

The friction and lubrication characteristics of joint cartilage were investigated using the metatarso-phalangeal joint cartilage of rabbit against rotating stainless steel disk. Friction tests were conducted by dry and bovine serum lubricated sliding at room and body temperatures. For the dry sliding tests, low friction coefficient of 0.1-0.15 was observed at the early period of test, and then the friction coefficient increased as a test continued. With increasing applied load the early period of low friction lengthens. For the lubricated sliding tests, the coefficient of friction decreased as the applied load increased. And also the coefficient of friction decreased continuously to 0.07 as the test duration increases. These results can be interpreted that the squeeze or weeping lubrication mechanism dominates the friction and lubrication characteristics in the joint cartilage of rabbit.

• Tribology and Lubricants
• /
• 제24권5호
• /
• pp.215-220
• /
• 2008

An internal friction model was developed to model the frictional behavior of automotive Constant Velocity (CV) joints by using the test data from an instrumented CV joint friction apparatus with actual driveshaft assemblies. Experiments were conduced under different realistic operating conditions of oscillatory speeds, CV joint articulation angles, lubrication, and torque. The experimental data were used to develop a physics-based semi-empirical CV joint internal friction coefficient model as a function of different CV Joint operating parameters. It was found that the proposed friction model captures the experimental results well not only the static behavior of friction coefficient, but also the dynamic friction terms, which is the main source of force that causes vehicle vibration problems.

• Tribology and Lubricants
• /
• 제23권2호
• /
• pp.61-65
• /
• 2007

It is very important to connect machinery and maintain it. This is usually done by bolt joint. There are two ways in connecting the bolt joint : the angle method and the torque method. The torque method is a method that let the clamping force maintain. The underhead of the bolt's head and the thread friction are the main influences. This study focuses on how the clamping farce and friction coefficient change under the condition in vibrating the underhead of the bolt's head part. As a result, under vibration condition, we found out that the clamping farce increases, while the friction coefficient decreases.

• International Journal of Automotive Technology
• /
• 제8권6호
• /
• pp.723-730
• /
• 2007

The typical design of automotive driveshafts generally utilizes Constant Velocity(CV) joints as a solution to NVH. CV joints are an integral part of vehicles and significantly affect steering, suspension, and vehicle vibration comfort levels. Thus, CV joints have been favored over universal joints due to the constant velocity torque transfer and plunging capability. Although CV joints are common in vehicle applications, current research works on modeling CV joint friction and assumes constant empirical friction coefficient values. However, such models are long known to be inaccurate, especially under dynamic conditions, which is the case for CV joints. In this paper, an instrumented advanced CV joint friction apparatus was developed to measure the internal friction behavior of CV joints using actual tripod-type joint assemblies. The setup is capable of measuring key performance of friction under different realistic operating conditions of oscillatory speeds, torque and joint installation angles. The apparatus incorporates a custom-installed triaxial force sensor inside of the joint to measure the internal CV joint forces(including friction). Using the designed test setup, the intrinsic interfacial parameters of CV joints were investigated in order to understand their contact and friction mechanisms. The results provide a better understanding of CV joint friction characteristics in developing improved automotive driveshafts.

• Tribology and Lubricants
• /
• 제29권4호
• /
• pp.223-227
• /
• 2013

A GAF (generated axial force) is produced at a plunging-type CVJ (constant velocity joint). A high GAF can cause vibrations in a vehicle. Grease is used to reduce friction between the roller and the track of the outer case of a CVJ. The grease performance depends on the surface conditions and operating temperature. The surface of the outer case is extremely rough and hard. In recent times, the maximum operating temperature of CVJs has crossed $140^{\circ}C$, because the exhaust line is now located close to the CVJ. In this study, we examined the friction characteristics of friction additives at $25-150^{\circ}C$ and determined an optimal formulation with a low friction coefficient. This formulation can be used to develop low-friction grease that can reduce the GAF produced at a CVJ by approximately 7-26%.

• 한국운동역학회지
• /
• 제25권3호
• /
• pp.363-370
• /
• 2015

Objective : The purpose of this study was to give the basic data for the cutting movement with the various angels on the poly urethane. Method : Ten healthy men voluntarily participated in this study. A three-dimensional motion analysis system (VICON) and force plates were used to analyze the movements of the joints for the lower extremities. For the statistical analysis the IBM SPSS 21.0 was used to perform repeated measured ANOVA and post-hoc comparison result was used to perform the Scheffe and the level of significance was set up at ${\alpha}=.05$. Results : There were significant differences for the time required for the increasing angles of the cutting movement(p<.05). In addition, there were significant differences for the maximum dorsiflexion, plantarflexion of ankle joint, maximum flexion of knee joint and hip joint with the increasing the angles of cutting movement(p<.05). Also, there were significant differences for the maximum adduction and abduction angle of the hip joint with the increasing of the angles of cutting movement. There was signigicant difference for the resultant utilized coefficient of friction(RuCOF) for the increasing angles of cutting movement(p<.05). Conclusion : There was a pattern to increase the coefficient friction with the angle of cutting direction. Also, it would be possible to use the poly urethane for the outdoor floor with the results of this study.

• Journal of the Korean Wood Science and Technology
• /
• 제39권5호
• /
• pp.437-443
• /
• 2011

In Korea, there has been a traditional post and beam wood construction with large roof load. Because a large friction is generated in wooden joint or members, it is important to evaluate the friction between wood members according to wood direction. Because most of studies have been concerned with friction between wood and steel, excluding effect of real area of contact, there are a few studies on the friction between wood members. The object of this study was to evaluate friction or coefficient of friction according to normal force and real area of contact of wood. With Japanese larch (Larix kaempferi) test specimens, five steps of normal force and combinations of test were prepared. Results indicated that normal force had almost no affection on the friction, however there was difference about friction or coefficient of friction according to real contact conditions of wood grain and contact area.

• Tribology and Lubricants
• /
• 제27권6호
• /
• pp.332-337
• /
• 2011

The object of this experimental study is to investigate influences of vibrator amplitude on clamping force in vibration for bolted joint. The experiment is that change the vibrator amplitude to check clamping force. also the friction coefficient calculated by equation to use an obtained in experiments. The main purpose of generation vibrations is decreasing the clamping force dispersion. also If vibration occurs while tightening the bolt is reduced coefficient of friction. In this paper, In experiments to measure the clamping force before vibrator's amplitude changing. Vibrator's amplitude changes to 5.5mm from 4.4mm. As a result, under various vibration condition, relationship of clamping force and Vibrator amplitude.

• 한국소음진동공학회논문집
• /
• 제23권12호
• /
• pp.1090-1095
• /
• 2013

This paper describes the FEM analysis for squeak problem of the ceramic-on-ceramic hip joint system. The onset of hip squeak is estimated by the positive real parts of the eigenvalues in the hip joint system. From the complex eigenvalue analysis, the unstable frequencies and the corresponding mode shapes are determined at the certain severe friction coefficients. It is found that some bending and torsion modes of the femoral stem can be unstable due to the mode-coupling mechanism. It also shows that the magnitude of the friction coefficient plays a key role on the occurrence of hip squeak.