• Structural Engineering and Mechanics
• /
• v.81 no.4
• /
• pp.481-492
• /
• 2022

Cycloidal ball planetary transmission (CBPT) has many applications as precision reducer, such as precision machinery and automation drive systems etc. The traditional analytical model of CBPT cannot accurately describe the change of the normal force of meshing points, and thus cannot describe the precise transmission process of meshing pairs. In the paper, a method for deriving the normal force equation is put forward by using the non-linear relationship between force and deformation in elastic mechanics. The two-point contact analytical models of all the meshing pairs are established to obtain the micro-displacement analytical model of CBPT under axial pre-tightening. Then, the non-real-time two-point contact analytical models of all the meshing pairs are further constructed to obtain the normal force expression to determine the critical compression coefficients. Experimental investigations are performed to verify the analytical model using the critical compression coefficients.

• Tribology and Lubricants
• /
• v.38 no.5
• /
• pp.199-204
• /
• 2022

This paper presents a numerical investigation of the influence of water molecule thickness on frictional behavior at the nanoscale using molecular dynamics simulation. Three different models, comprising water thin films of various thicknesses, were built, and indentation and sliding simulations were performed using the models. Various normal loads were applied by indenting the Si tip on the water film for the sliding simulation to evaluate the interplay between the water thin film thickness and the normal load. The results of the simulations showed that the friction force generally increased with respect to the normal load and thickness of the water thin film. The friction coefficient varied with respect to the normal load and the water film thickness. The friction coefficient was the smallest under a moderate normal force and increased with decreasing or increasing normal loads. As the water film became thicker, the contact area between the tip and water film became larger. Under well-lubricated conditions, the friction force was proportional to the contact area regardless of the water film thickness. As the normal force increased above a critical condition, the water molecules beneath the Si tip spread out; thus, the film could not provide lubrication. Consequently, the substrate was permanently deformed by direct contact with the Si tip, while the friction force and friction coefficient significantly increased. The results suggest that a thin water film can effectively reduce friction under relatively low normal load and contact pressure conditions. In addition, the contact area between the contacting surfaces dominates the friction force.

• Proceedings of the KIEE Conference
• /
• 2000.07b
• /
• pp.894-896
• /
• 2000

In this paper, we have designed the advanced DVT HLSM inserted a permanent magnet into the slot in order to improve the thrust force without increasing the normal force. And it was analyzed the characteristics of thrust force and normal force of the new HLSM by using Finite Element Method and Virtual Work Method. As a result of this paper it was confirmed that the thrust force characteristics of the new HLSM improved about 23% in comparision with DVT HLSM without increasing the normal force.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.51 no.12
• /
• pp.659-663
• /
• 2002

The brake systems of high-speed train are to be equipped with three different brake systems, such as regenerative brake with regenerative feedback in driving car, a pneumatic disc brake, and non-contact linear eddy-current brake(ECB). The regenerative brake and the pneumatic disc brake are acting on the wheels. Their achievable braking force depends on the adhesive coefficient, which is influenced by the weather condition and speed, between the wheel and The linear eddy current brake gets an economical solution in the high-speed train because of the independence of the adhesive coefficient, no maintenance needed. and the good control characteristics. The braking force and the normal force of ECB for korean high-speed train are analysed by the 2D FEM(Finite Element Method). Finally the normal force is compared with the experiential values to verify the analysis.

• Journal of the Korean Wood Science and Technology
• /
• v.39 no.5
• /
• 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.

• The Bulletin of The Korean Astronomical Society
• /
• v.44 no.2
• /
• pp.71.3-71.3
• /
• 2019

Previously we developed a method of coronal force-free field construction using vector potentials. In this method, the boundary normal component of the vector potential should be adjusted at every iteration step to implement the boundary normal current density, which is provided by observations. The method was a variational method in the sense that the excessive kinetic energy is removed from the system at every iteration step. The boundary condition imposing the normal current density, however, is not compatible with the variational procedure seeking for the minimum energy state, which is employed by most force-free field solvers currently being used. To resolve this problem, we have developed a totally new method of force-free field construction. Our new method uses a unique magnetic field description using two scalar functions. Our procedure is non-variational and can impose the boundary normal current density exactly. We have tested the new force-free solver for standard Low & Lou fields and Titov-Demoulin flux ropes. Our code excels others in both examples, especially in Titov-Demoulin flux ropes, for which most codes available now yield poor results. Application to a real active region will also be presented.

• Journal of Institute of Control, Robotics and Systems
• /
• v.20 no.6
• /
• pp.663-668
• /
• 2014

This paper presents a hook-type finger force measuring system with force sensors. The system is composed of a body, two three-axis force sensors, a hook, and so on. The two three-axis force sensors system was specially designed using FEM(Finite Element Method) and fabricated using strain-gages. The sensors measure the finger forces of both normal people and handicapped people in the system, and the forces are combined. The developed hook-type finger force measuring system can measure the pulling finger force of both normal and handicapped people. The pulling force tests of men and women were performed using the developed the system. It is thought that the developed system can be used to measure the pulling force of fingers.

• Transactions on Electrical and Electronic Materials
• /
• v.10 no.5
• /
• pp.156-160
• /
• 2009

In an ultrasonic motor, a piezoelectric ceramic material forms the active element which vibrates the stator, thus initiating the rotational motion. In the operation of ultrasonic motors, many factors exist that can affect the resonance characteristics of the piezoelectric ceramic component. For examples, these factors are the bonding conditions with the piezoelectric element, the magnitude of the input voltage, the normal force in the frictional drive and the emission of heat due to vibration and friction etc. Therefore, it is important to research properly the inclination for variation of piezoelectric ceramics in the circumstance where complex elements are involved. In this paper, we focus on the analysis of the resonance characteristics of an ultrasonic motor as a function of the magnitude of the input voltage and the normal force.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.55 no.11
• /
• pp.582-588
• /
• 2006

This paper presents the characteristics analysis and normal force minimization of a synchronous permanent magnet planar motor(SPMPM) with Halbach magnet way. Firstly, the flux density distribution is calculated by analytical method; then, the characteristics of this SPMPM are evaluated, some experiments have been done to verify the analysis propriety and to investigate the interaction among the characteristics; At last, the normal force is minimized by using genetic algorithm and it is decreased from 672.83[N] to 144.24[N] remarkably.

• Proceedings of the KIEE Conference
• /
• 1999.07a
• /
• pp.151-153
• /
• 1999

The normal force and vibration characteristic are affected by tooth shapes of linear pulse motor. In this paper, we obtained the normal force according to the position of mover and tooth shapes using the finite element analysis. From the result, we can find the vibration characteristics. Also we predict the characteristics of normal force and vibration.