• Journal of the Korean Society for Precision Engineering
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• v.10 no.4
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• pp.206-215
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• 1993

The finite element method is applied to analyze the mechanism of metal cutting, especially micro metal cutting. This paper introduces some effects, such as constitutive deformation laws of workpiece material, friction of tool-chip contact interfaces, tool rake angle and also simulate the cutting process, chip formation and geometry, tool-chip contact, reaction force of tool. Under the usual plane strain assumption, quasi-static analysis were performed with variation of tool-chip interface friction coefficients and tool rake angles. In this analysis, cutting speed, cutting depth set to 8m/sec, 0.02mm, respectively. Some cutting parameters are affected to cutting force, plastic deformation of chip, shear plane angle, chip thickness and tool-chip contact length and reaction forces on tool. Several aspects of the metal cutting process predicted by the finite element analysis provide information about tool shape design and optimal cutting conditions.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.539-544
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• 2004

This paper discusses the measurement of tire driving performance for 2 types of tire model. Tire is almost composed of rubber, and this is related with the bearing capacity of tire due to the external force. In this study, an explicit time integration method has been used to simulate steady state rolling along a straight path and over a cleat. And analysis for tire dynamic response rolling over a cleat is importnat to study automobile NVH properties. Besides, the evaluation of contact shear force is perfomed for steady state rolling and braking state. The results show that there are noticeable differences between 205/60R15 and 225/60R15 tire model.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.5
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• pp.142-149
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• 2009

This paper proposes and demonstrates novel flexible contact force sensing devices for 3-dimensional force measurement. To realize the sensor, polyimide and polydimethylsiloxane are used as a substrate, which makes it flexible. Thin-film metal strain gauges, which are incorporated into the polymer, are used for measuring the three-dimensional contact forces. The force sensor characteristics are evaluated against normal and shear load. The fabricated force sensor can measure normal loads up to 4N. The sensor output signals are saturated against load over 4N. Shear loads can be detected by different voltage drops in strain gauges. The device has no fragile structures; therefore, it can be used as a ground reaction force sensor for balance control in humanoid robots. Four force sensors are assembled and placed in the four corners of the robot's sole. By increasing bump dimensions, the force sensor can measure load up to 20N. When loads are exerted on the sole, the ground reaction force can be measured by these four sensors. The measured forces can be used in the balance control of biped locomotion system.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.389-395
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• 2001

To restrain contact failure, present study investigates the influence of edge machining of an indenter (punch). As for the edge machining, rounding, chamfering, and chamfering and rounding are considered. Contact mechanics is consulted to examine the traction profile and the size of the contact region which are directly influenced by the end profile of the indenter. The effect of rounding size (i.e., radius) in the case of the chamfering and rounding edge-indenter is studied. Shear traction is also evaluated within the regime of partial slip. Size of slip region and its expansion rate due to the increase of shear force are considered to investigate the shape effect of the indenter on contact failure.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.6
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• pp.1365-1381
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• 1990

A $C^{0}$ continuous displacement finite element method based on a higher-order shear deformation theory is employed in the prediction of the transient response of laminated composite plates subjected to low-velocity impact. A modified contact law was applied to calculate the contact force during impact. The discrete element chosen is a nine-noded quadrilateral with 5 degree-of-freedom per node. The Wilson-.theta. time integration algorithm is used for solving the time dependent equations of the impactor and the central difference method was adopted to perform time integration of the plate. Numerical results, including the contact force history, deflection, and velocity history, are presented. Comparisons of numerical results using a higher order theory and a first-order theory show that using a higher order theory provides more accurate results. Effects of boundary condition, impact velocity, and mass of the impactors are also discussed.d.

• Geomechanics and Engineering
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• v.14 no.1
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• pp.61-69
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• 2018

The first part shows the optimal contact surface for T-shaped combined footings to obtain the most economical dimensioning on the soil (optimal area). This paper presents the second part of a new model for T-shaped combined footings, this part shows a the mathematical model for design of such foundations subject to axial load and moments in two directions to each column considering the soil real pressure acting on the contact surface of the footing with one or two property lines restricted, the pressure is presented in terms of an axial load, moment around the axis "X" and moment around the axis "Y" to each column, and the methodology is developed using the principle that the derived of the moment is the shear force. The classic model considers an axial load and a moment around the axis "X" (transverse axis) applied to each column, i.e., the resultant force from the applied loads is located on the axis "Y" (longitudinal axis), and its position must match with the geometric center of the footing, and when the axial load and moments in two directions are presented, the maximum pressure and uniform applied throughout the contact surface of the footing is considered the same. To illustrate the validity of the new model, a numerical example is presented to obtain the design for T-shaped combined footings subjected to an axial load and moments in two directions applied to each column. The mathematical approach suggested in this paper produces results that have a tangible accuracy for all problems.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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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.

• Korean Journal of Applied Biomechanics
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• v.30 no.2
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• pp.145-154
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• 2020

Objective: The purpose of this study was to determine the relationship between impact and shear peak force, and tibia-accelerometer variables during running. Method: Twenty-five male heel strike runners (mean age: 23.5±3.6 yrs, mean height: 176.3±3.3 m/s, mean mass: 71.8±9.7 kg) were recruited in this study. The peak impact and anteroposterior shear forces during treadmill running (Bertec, USA) were collected, and impact shock variables were computed by using a triaxial accelerometer (Noraxon, USA). One-way ANOVA was used to test the influence of the running speed on the parameters. Pearson's partial correlation was used to investigate the relationship between the peak impact and shear force, and accelerometer variables. Results: The running speed affected the peak impact and posterior shear force, time, slope, and peak vertical and resultant tibial acceleration, slope at heel contact. Significant correlations were noticed between the peak impact force and peak vertical and resultant tibia acceleration, and between peak impact average slope and peak vertical and resultant tibia acceleration average slope, and between posterior peak (FyP) and peak vertical tibia acceleration, and between posterior peak instantaneous slop and peak vertical tibial acceleration during running at 3 m/s. However, it was observed that correlations between peak impact average slope and peak vertical tibia acceleration average slope, between posterior peak time and peak vertical and resultant tibia acceleration time, between posterior peak instantaneous slope and peak vertical tibial acceleration instantaneous slope during running at 4 m/s. Conclusion: Careful analysis is required when investigating the linear relationship between the impact and shear force, and tibia accelerometer components during relatively fast running speed.

• Applied Microscopy
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• v.24 no.3
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• pp.87-93
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• 1994

In order to elucidate the machinability of lead brass, orthogonal machining experiment was conducted in SEM(Scanning Electron Microscope) equipped with a micro-machining device at a cutting speed of $7{\mu}m/s$ for brass containing 0.2 to 3wt% Pb. The microfactors (i.e., shear angle, contact length between chip and tool) were determined by in-situ observations. Machinability of brass containing lead is discussed in terms of the microfactors and the cutting resistant force tested by lathe cutting. The dynamic behavior of the chip formation of lead brass during the machining process was examined: The chips of lead brass form as a shear angle type. The shear angle increases with the content of lead in (6:4) brass. The pronounced effect of lead on the contact length between chip and tool was observed above 1% Pb. The cutting resistant force tested by lathe decreases remarkably with the lead content in brass. The observed microfactors are in close relation to the tested resistant force in macromachining.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.2
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• pp.252-261
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• 1988

Through the careful interpretation of the results of the cutting tests carried out in this study, it is found that under the cutting conditions when the internal shear of the chips take place the cutting can be treated essentially as a steady state problem. A new shear angle equation has been developed employing the conditions of force and moment equilibrium about the tool edge and the stress distribution model suggested by Zorev.The equation contains the chip-tool contact length C and stress distribution index n as important parameters.