• KSTLE International Journal
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• v.3 no.1
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• pp.60-67
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• 2002

Wear on the tube-to-spring contact is investigated experimentally, The vibration of the tube causes the wear while the springs support it As for the supporting conditions, the contacting normal farce of 5 N,0 N and the gap of 0.1 mm are applied. The gap condition is for considering the influence of simultaneous impacting and sliding on wear. The wear volume and depth decreases in the order of the 5 N,0 N and the gap conditions. This is explained from the contact geometry of the spring, which is convex of smooth contour, The contact shear force is regarded smaller in the case of the gap existence compared with the other conditions. The wear mechanism is considered from SEM observation of the worn surface. The variation of the normal contact traction is analysed using the finite element analysis to estimate the slip displacement range on the contact with consulting the fretting map.

• Journal of the Korean Society for Railway
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• v.17 no.1
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• pp.14-18
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• 2014

Wheel/rail contact is a significant problem in railway dynamics. In this paper, the wheel/rail contact is examined analytically and numerically as a contact problem between two cylinders where torque and friction have effect. Furthermore, the contact of a real wheel and rail is investigated numerically where the normal and shear force act. This study demonstrates that the wheel/rail contact is a process that generates traction force through creep where rolling and sliding occurs simultaneously depending on the shape of the wheel and rail, and the friction coefficient between them.

• Structural Engineering and Mechanics
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• v.72 no.6
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• pp.775-783
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• 2019

The present study deals with the numerical analysis of the symmetric contact problem of two bonded layers resting on an elastic half plane compressed with a rigid punch. In this context, Finite Element Method (FEM) based software called ANSYS and ABAQUS are used. It is assumed that the elastic layers have different elastic constants and heights and the external load is applied to the upper elastic layer by means of a rigid stamp. The problem is solved under the assumptions that the contact between two elastic layers, and between the rigid stamp are frictionless, the effect of gravity force is neglected. To validate the constructed model and obtained results a comparison is performed with the analytical results in literature. The numerical results for normal stresses and shear stresses are obtained for various parameters of load, material and geometry and are tabulated and illustrated.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.4
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• pp.598-614
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• 1998

This study was performed to investigate the influence of lateral guidance pattern and chewing pattern on masticatory muscle activity and occlusal contact pattern. Twenty-five patients with temporomandibular disorders and thirty students without temporomandibular disorders were selected for this study. Electromyographic examination and occlusal contact examination were performed simultaneously with Bio-Pak System (Bioresearch Inc.,U.S.A.) and T-Scan System(Tekscan Co., USA). The obtained results were as follows : 1. The EMG activity of masseter and anterior temporal muscle in patient group with canine guidance was higher than with non-canine guidance. but there was no significant difference (p>0.05). 2. The EMG activity of anterior temporal muscle in normal group with non-canine guidance was higher at preferred chewing side than at opposite side (p<0.05). 3. The EMG activity of masseter muscle was higher in normal group than in patient group (p<0.05). 4. The number of occlusal contact in patient group with canine guidance was higher than with non-canine guidance, but there was no significant difference (p>0.05). 5. The occlusal contact force at preferred chewing side was higher in patient group than in normal group(p<0.05).

• Tribology and Lubricants
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• v.29 no.3
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• pp.160-166
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• 2013

There is an indispensable need for force calibration for quantitative nanoscale force measurement using atomic force microscopy. Calibrating the normal force is relatively straightforward, whereas doing so for the lateral force is often complicated because of the difficulty in determining the optical lever sensitivity. In particular, the lateral force calibration of a colloidal probe in a liquid environment often has a larger uncertainty as a result of the effects of the epoxy, the location of the colloidal particle on the cantilever, and a decrease in the quality factor. In this work, the lateral force of a colloidal probe using a reference cantilever with a known spring constant was calibrated in a liquid environment. By obtaining the spring constant and the lateral sensitivity at the equator of a spherical colloidal particle, the damage to the bottom surface of the colloidal particle could be eliminated. Further, it was shown that the effect of the contact stiffness on the determination of the lateral spring constant of the cantilever could be minimized. It was concluded that this method can be effectively used for the lateral force calibration of a colloidal probe in a liquid environment.

• Tribology and Lubricants
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• v.21 no.5
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• pp.209-215
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• 2005

Nano/micro friction with the contact area was studied on Si-wafer (100) and diamond-like carbon (DLC) film. Borosilicate balls of radii $0.32{\mu}m,\;0.5{\mu}m,\;1.25{\mu}m\;and\;2.5{\mu}m$ mounted on the top of AFM tip (NPS) were used for nano-scale contact and Soda Lime glass balls of radii 0.25mm, 0.5mm, 1mm were used for micro-scale contact. At nano-scale, the friction between ball and surface was measured with the applied normal load using an atomic force microscope (AFM), and at micro scale it was measured using ball-on flat type micro-tribotester. All the experiments were conducted at controlled conditions of temperature $(24\pm1^{\circ}C)$ and humidity $(45\pm5\%)$. Friction was measured as a function of applied normal load in the range of 0-160nN at nano scale and in the range of $1000{\mu}N,\; 1500{\mu}N,\;3000{\mu}N\;and\;4800{\mu}N$ at micro scale. Results showed that the friction at nano scale increased with the applied normal load and ball size for both kinds of samples. Similar behavior of friction with the applied normal load and ball size was observed for Si-wafer at micro scale. However, for DLC friction decreased with the ball size. This difference of in behavior of friction in DLC nano- and microscale was attribute to the difference in the operating mechanisms. The evidence of the operating mechanisms at micro-scale were observed using scanning electron microscope (SEM). At micro-scale, solid-solid adhesion was dominant in Silicon-wafer, while plowing in DLC. Contrary to the nano scale that shows almost a wear-less situation, wear was prominent at micro-scale. At nano- and micro-scale, effect of contact area on the friction was discussed with the different applied normal load and ball size.

• The Journal of Korea Robotics Society
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• v.12 no.3
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• pp.322-331
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• 2017

In this paper we present a novel robotic palpation method for the lump shape estimation using contact pressure distribution. Many previous researches about the robotic palpation have used a stiffness map, which is not suitable to obtain geometrical information of a lump. As a result, they require a large data set and long palpation time to estimate the lump shape. Instead of using the stiffness map, the proposed palpation method uses the difference between the normal force direction and the surface normal to detect the lump boundary and estimate its normal. The palpation trajectory is generated by the normal of the lump boundary to track the lump boundary in real-time. The proposed approach requires small data set and short palpation time for the lump shape estimation since the shape can be directly estimated from the optimally generated palpation trajectory. An experiment result shows that our method can find the lump shape accurately in real-time with small data and short time.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.1
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• pp.59-68
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• 2013

The objective of this study was to analyze occlusal contact pattern of 33 young adult males with normal occlusion during lateral excursion using T-scan III system which can measure the dynamic occlusion. Occlusal contact patterns were examined and categorized in non-working side disclusion point(more functionally acceptable position) not canine-to-canine position. Disclusion time, occlusal force, and occlusal force distribution ratio of upper canine at disclusion point during lateral excursion movement was also measured and compared among the groups divided according to contact patterns. The results showed that group function was clearly more dominant than canine guidance and other occlusal contact patterns different with existing patterns were found. There were significantly difference between groups in variables of T-scan measurement. T-scan III system is effective tools to analyze and evaluate occlusal contact patterns, disclusion time, occlusal force, and occlusal force distribution ratio of upper canine at disclusion point.

• Journal of the Korean Geotechnical Society
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• v.23 no.3
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• pp.77-88
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• 2007

A micromechanics-based model to simulate the elastic and elastic-plastic behavior of granular soils is developed. The model accounts for the fabric anisotropy represented by the statistical parameter of the spatial distribution of contact normals, the evolution of fabric anisotropy as a function of stress ratio, the continuous change of the co-ordination number relating to the void ratio, and the elastic and elastic-plastic microscopic contact stiffness. Using the experimental data for metallic materials, the elastic-plastic contact stiffness is derived as a power function of the normal contact force as well as the contact force initiating the yielding of contact bodies. To quantitatively assess microscopic model parameters, approximate solutions of cross-anisotropic elastic moduli are derived in terms of the micromechanical parameters.

• Journal of Mechanical Science and Technology
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• v.20 no.6
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• pp.806-818
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• 2006

The shear spinning process, where the plastic deformation zone is localized in a very small portion of the workpiece, shows a promise for increasingly broader application to the production of axially symmetric parts. In this paper, the three components of working force are calculated by the newly proposed deformation model in which the spinning process is understood as shearing deformation after uniaxial yielding by bending, and shear stress, $\tau_{rz}$ becomes $\kappa$, yield limit in pure shear, in the deformation zone. The tangential forces are first calculated and the feed forces and the normal forces are obtained by the assumption of uniform distribution of roller pressure on the contact surface. The optimum contact area is obtained by minimizing the bending energy required to get the assumed deformation of the blank. The calculated forces are compared with experimental results. A comparison shows that theoretical prediction is reasonably in good agreement with experimental results.