• Tribology and Lubricants
• /
• v.15 no.2
• /
• pp.199-205
• /
• 1999

Using a coupled thermal-mechanical analysis, the thermal distortion of the ventilated disk brakes has been investigated based on the air cooling effects during 15 braking operations. The FEM results show that the bendings and distortions of the disk toward the left side are decreased, but the sinusoidal distortion of the disk rubbing surface along the arc length of the vent hole is highly increased by increasing the convective air cooling effects, which is heavily related to the squeal, wear and micro-thermal crackings at the rubbing surfaces due to uneven dissipation rates of friction heatings.

• 한국금형공학회:학술대회논문집
• /
• 2008.06a
• /
• pp.27-30
• /
• 2008

It was investigated that two rods of aluminium can be welded by hot extru-welding method with extru-welding dies, and that the extru-welding on the welding surface were analyzed by computer simulation according to the steped shapes of welding dies. It was known by computer simulation that welding pressure on the welding section of rods welded using extru-welding dies and that the welding pressure on the welding section of rods using extru-welding dies is lowerer than the welding pressure of rods using stepped welding dies. And it was known by experiments that two rods of aluminium can be welded on the end sections by hot extru-welding method using fan-shaped stepped welding dies without relative rotational movement of contacted aluminium rods needed for the purpose of friction heating and pressure.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2001.06a
• /
• pp.248-256
• /
• 2001

Capacities of screw are pumping, steady flow of polymer melts, volumetric efficiency, steady volumetric throughout etc. they are affected by geometry of screw, heat flux, pressure on inside barrel, rotating velocity, friction coefficient at screw surface etc. Also the temperature of polymer melts by heating pad and injection pressure play a very important role in the injection molding machine. by computation volumetric efficiency increases as rotating velocity increases, flight number increses, and decreases as friction coefficient increases. but volumetric throughout is different :s flight number increases with helix angle variability. so in this paper we analyze thermal distortion and stress of screw includes pressure and temperature distributions by finite element analysis to understand what design factors influence on thermo-mechanical characteristics of screw.

• Journal of the Korean Institute of Gas
• /
• v.19 no.3
• /
• pp.49-53
• /
• 2015

The purpose of this paper is to study and analyze the failure examples for fire by friction on clutch, manual transmission and tire system in a car. In the first example, the driver took the pedal with foot to act the clutch. But the clutch disk did not return from flywheel by leakage of clutch hydraulic line. The heat was produced between clutch disk and flywheel by surface contacting. As a result, it was produced the fire by oil sludge sticked with transmission. In the second example, the transmission system was operated to transfer power of engine by contacting with gear and gear. But, as if the oil of transmission was caused the oil insufficiency because of leaking by crack of transmission case, it found the fact that was produced the fire by deposit material on transmission case. In the third example, when the car's driver continuously pushed an accelerator pedal for escaping from dry pit, the tire took the heat by the friction force between tire and surface of road. As a result, it became the direct cause for the fire. Therefore the driver must manage not to produce the fire with friction parts by heating during running.

• Tribology and Lubricants
• /
• v.12 no.3
• /
• pp.79-84
• /
• 1996

One of the greatest dangers in mechanical face seals is the formation of heat checking and thermal stress cracks on the sliding surfaces. These thermal distortions due to non-uniform heating lead to increase the leakage of the sealed fluids and wear, and with balance of the seal can cause the seal faces to part. In this study heat checking and thermal stress cracks are investigated experimentally. These thermal distortions are explained using the thermal models of the conatct geometries between the seal ring and the seal seat. To overcome these thermal problems, the thermohydrodynamic seal is presented. The newly developed mechanical seal may substantially reduce the friction torque, frictional heating which causes heat checking and thermal stress cracks, and wear.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1997.04a
• /
• pp.232-241
• /
• 1997

The tribological behavior for MoS$_2$ bonded films is evaluated according to the international standard testing methods, such as ASTM D 2625(Falex tester) and ASTM D 2714(LFW-1 tester). It has been well known that the tribological behavior for MoS$_2$ bonded films is affected by several factors. However, in this work, the wear life for MoS$_2$ bonded films is mainly experimentally measured with different contact geometry, and evaluated in terms of the frictional heating according to the contact geometry of tribotester. The test results show that the wear life of MoS$_2$ bonded films is significantly affected not only by the frictional heating, but also by the contact pressure, test running-in conditions, and the contact conformity.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.20 no.3
• /
• pp.175-180
• /
• 2008

Flow quantity to supply to a coil in floor heating system is important to achieve comfortable indoor air condition in the winter season. The hot water header is used to distribute the water into the coil. Experimental study has been performed using the water header that have 5 branches consisted of flow control valves and automatic shut-off valves. Each branch line connected it with X-L pipe. Experimental tests accomplished it to investigate the flow distribution characteristics of the hot water header. Experimental results show that the selection of the pump head and differential pressure are very important to save running energy of the system, and high differential pressure needs more friction loss in the case of suitable differential pressure for balancing of the header.

• Nuclear Engineering and Technology
• /
• v.49 no.8
• /
• pp.1654-1659
• /
• 2017

The boundary layer of a two-dimensional forced convective flow along a persistent moving horizontal needle in an electrically conducting magnetohydrodynamic dissipative nanofluid was numerically investigated. The energy equation was constructed with Joule heating, viscous dissipation, uneven heat source/sink, and thermal radiation effects. We analyzed the boundary layer behavior of a continuously moving needle in Blasius (moving fluid) and Sakiadis (quiescent fluid) flows. We considered Cu nanoparticles embedded in methanol. The reduced system of governing Partial differential equations (PDEs) was solved by employing the Runge-Kutta-based shooting process. Computational outcomes of the rate of heat transfer and friction factors were tabulated and discussed. Velocity and temperature descriptions were examined with the assistance of graphical illustrations. Increasing the needle size did not have a significant influence on the Blasius flow. The heat transfer rate in the Sakiadis flow was high compared with that in the Blasius flow.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.13 no.12
• /
• pp.1275-1281
• /
• 2001

Aqueous polymer solutions are known to have small pressure reduction. Paraffin slurries are known to have high thermal capacity. Paraffin particles are mixed into an aqueous polymer solution to make a new heat transfer fluid having high thermal capacity but low pressure reduction. The heat transfer characteristics of the new slurry was tested in a circular tube having a constant heat transfer boundary condition. The new slurry was found to have high Nusselt numbers as well as high thermal capacity and low pressure reduction in the laminar flow. The trends of the Nusselt numbers along the heating test section were studied for various heating conditions.

• Tribology and Lubricants
• /
• v.13 no.3
• /
• pp.20-27
• /
• 1997

The tribological behavior for $MoS_2$ bonded films is evaluated according to the international standard testing methods, such as ASTM D 2625 (Falex tester) and ASTM D 2714 (LFW1 tester). It has been well known that the tribological behavior for $MoS_2$ bonded films is affected by several factors. However, in this work, the wear life for $MoS_2$ bonded films is mainly experimentally measured with different contact geometry, and evaluated in terms of the frictional heating according to the contact geometry of tribotester. The test results show that the wear life of $MoS_2$ bonded films is significantly affected not only by the frictional heating, but also by the contact pressure, test running-in conditions, and the contact conformity.