• Coupled systems mechanics
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• v.4 no.3
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• pp.237-249
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• 2015

In the gear meshing process, gear temperature field concerns the meshing surface friction, the friction heat depends on the contact pressure, the contact pressure is affected by the elastic deformation of gears and the temperature field caused by the thermal deformation, so the temperature field, stress field and displacement field should be mutual coupling. It is necessary to consider in meshing gear pair in the operation process of thermodynamic coupling contact stress (TCCS) and thermodynamic coupling deformation (TCD), and based on thermodynamic coupling analysis (TCA) of gear teeth deformation.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.645-650
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• 2003

Wheel/Rail geometric constraint relationships, such as effective conicity and gravitational stiffness, strongly influence the lateral dynamics of railway vehicles. In general, these geometric contact characteristics are nonlinear functions of the wheelset lateral displacement. There is a need to develop a wheel/rail contact simulation program for wheels and rails with arbitrary profiles for the prediction of the dynamic behavior of railway vehicles. An algorithm to simulate any combination of wheels and rails is employed and a GUI for easy analysis is constructed. The simulation program is applied to KTX which will run on both KTX and conventional rails, two rail standards having different rail profiles. The results show that the two rail systems have different geometric contact characteristic

• Journal of applied mathematics & informatics
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• v.39 no.1_2
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• pp.31-43
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• 2021

A homogeneous circular disk undergoing a contact force is considered to investigate the thermo-elastic characteristics, and the inquiry is based on the variations of outer surface temperature and angular velocity. The intensity of stresses grows with the increase of outer surface temperature, and the circumferential strain reacts more sensitively to the change of outer surface temperature than the radial strain. In general, higher angular velocity produces; (i) larger expansion in the radial direction, (ii) smaller displacement in the circumferential, (iii) diminished intensity in the stresses. It is demonstrated that outer surface temperature and angular velocity are critical factors in the determination of thermo-elastic characteristics of homogeneous circular disks subjecting to a contact force. The results obtained can be applied on the design of a homogeneous circular cutter to promote proper and reliable thermos-elastic characteristics in service by the proper operation of these parameters.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.4
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• pp.119-126
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• 1995

This paper presents a non-contact measuring system using one point measuring method to measure surface profiles of dies and clay models for practical use in the field of production engineering. The system has a laser beam probe similar to a measuring probe in a contact measuring system and CCD linear sensor used to detect 300mm measurement range, displacement of measured surfaces, from an origin. There is no mechanical interference between this measuring system and a measured surface in this system. In this measuring system, it was needed 500-600ms including data processing time to measure one point. The experiments showed that the standard deviation was 800 .mu.m and the reproducibility was also 100-210 .mu. m.

• Korean Journal of Applied Biomechanics
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• v.14 no.3
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• pp.135-147
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• 2004

This study was conducted to investigate the technical factors of Lu Yu Fu vault actually performed by three men gymnasts participated in artistic gymnastics competition of 2003 summer Universiade in Daegu through the DLT method of three dimensional cinematography. To analyze these vaults, the instant events of Lu Yu Fu were set in the board touchdown(BTD), the board takeoff(BTO), the horse touchdown(HTD), the horse takeoff(HTO), the peak height(PH), the mat touchdown(MTD) respectively and the phases of that vault were set in the board contact(BC), the preflight(PRF), the horse contact(HC), the postflight(POF), the grounding on mat(GM) respectively After calculating the performance times, the CG displacement velocity, the kinetic energy impulse reaction force moment arm torque at the horse, the released angle piked angle addressed angle, the angular momentum angular velocity of whole body in x axis, and the horizontal displacement between the feet and CG, the following conclusions were reached. To perform the better Lu Yu Fu vault, a gymnast must have the large horizontal velocity of whole body with fast run-up, decrease the duration time and the horizontal vertical displacement of whole body in PRF, have the enough time to judge the correct magnitude and direction of force to brake or push the horse so as to lengthen the HC duration time at any cost. Also it is desirable to increase the horizontal vertical displacement of whole body in POF if possible, maintain the adequate piked position to decrease the angular velocity of whole body in x axis, prepare the grounding on mat previously and delay the release of the hand from the body to keep the angular momentum.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.5
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• pp.1947-1955
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• 2013

The purpose of this paper is to present an photoelasticity technique for measuring the displacement and stress distribution in particle assembly subjected to shallow foundation loading. Photoelastic measurement technique was employed to visualize the force transmission of a particle assembly. A model assembly bounded by a steel frame was built by stacking bi-dimensional circular particles made of polycarbonate elastomer. Each particle was coated by a thin photoelastic sheet so that the force transmission represented by bright light stripes can be visualized. In a contacted particle, both magnitude and orientation of principal stress difference can also be measured via the photoelasticity technique. The different distributions of the contact stresses at the initial loading and near the failure were quantitatively compared. The photoelastic patterns and displacement fields observed in the pre-failure state disappears immediately after the buckling of confined force chains.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.5
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• pp.94-100
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• 2002

This paper is concerned with the development, and performance test of LIPCA (Lightweight Piezo-composite Curved Actuator) that is lighter than other conventional piezo-composite type actuators. LIPCA is composed of top fiber composite layers with a high modulus and low CTE (Coefficient of Thermal Expansion), a middle PZT cermaic wafer, and base layers with a high modulus and high CTE. The performance of each actuator was evaluated using an actuator test system consisting of an actuator supporting jig, a high voltage actuating power supplier, and a non-contact laser measuring system. The simply supported condition actuator was excited by the power supplier with 1.0Hz cycle and up to $100\sim400V_{pp}$. The displacement at the center point of actuator was measured with non-contact laser displacement measuring system, It has been shown that the LIPCA-C2 can 34% decrease in mass and 13% increase in displacement compared to THUNDER.

• Journal of the Korea Society of Computer and Information
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• v.16 no.5
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• pp.61-71
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• 2011

To measure the fatigue of metallic objects at high speed vibration while non-contact precision displacement measurement on how to have a lot of research conducted. Noncontact high-speed vibration detection sensor of the eddy current sensors and laser sensors are used, but it is very expensive. Recently, High-speed vibrations detection using an inexpensive inductive sensor to have been studied, but is still a beginner. In this paper, a new design of an inexpensive inductive proximity sensor has been suggested in order to measure high frequency dynamic displacements of metallic specimens in a noncontact manner. Detection of the existing inductive sensors, detection, integral, and amplified through a process to detect the displacement noise due to weak nature of analog circuits and integral factor in the process of displacement detection is slow. The proposed method could be less affected by noise, the analog receive and high-speed signal processing is a new way, because AD converter (Analog to Digital converter) without using the vibration frequency signals directly into digital signals are converted. In order to evaluate the sensing performance, The proposed sensor module using non-contact vibration signals were detected while shaker vibration frequencies from 30Hz to 1,100 Hz at intervals of vibrating metallic specimens. Experimental results, Vibration frequency detection range of the metallic specimins within close proximity to contactless 5mm could be measured from DC to 1,100Hz and vibration amplitude of the resolution was $20{\mu}m$. Therefore, the proposed non-contact inductive sensor module for precision vibration detection sensor is estimated to have sufficient performance.

• Tribology and Lubricants
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• v.22 no.3
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• pp.119-126
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• 2006

In this paper, the contact behavior characteristics of a primary sealing components such as a seal ring and a seal seat has been presented for a small hydro-power turbine. Using the non-linear FEM analysis, the maximum temperature, the axial displacement, radial differences between a seal ring and a seal seat, and maximum contact normal stress have been analyzed for three optimized sealing profiles in which are designed based on the FEM analysis and Taguchi's experimental method. The three primary sealing profiles between a seal ring and a seal seat are strongly related to a leakage of a water for a hydro-power turbine and wear of a primary sealing component. The computed results show that the contact rubbing area between a seal ring and a seal seat is very important for reducing a friction heating and wear in a sealing gap, and increasing a contact normal stress in primary sealing components. Based on the FEM computation, models II and III in which have a small rubbing surface of seal rings show low dilatation of primary sealing components, and high normal contact stress between a seal ring and a seal seat. Thus, the FEM computed results recommend a short contacting width of a primary sealing component for reducing a leakage and thermal distortions, and expanding a seal life. This means that a conventional primary sealing component may be switched to a reduced sealing face of seal rings.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.3
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• pp.292-301
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• 2008

A linearized model for hysteretic acoustic nonlinearity of imperfectly joined interface is proposed and analyzed by using Coulomb damping to investigate the characteristics of the reflection and transmission coefficients for harmonic waves at the contact interface. Closed crack is modeled as non welded interface that has nonlinear discontinuity condition in displacement across its boundary. Based on the hysteretic contact stiffness of the contact interface, the reflected and transmitted waves are determined by deriving the tractions on both sides of the interface in terms of the discontinuous displacements across the interface. It is found that the amplitudes of the reflected and transmitted waves are dependent on the frequency and the hysteretic stiffness. As the frequency of the incident wave increases, the higher reflection and lower transmission are obtained. It also shows that the hysteresis of the interface increases the reflection coefficient, but reduces the transmission coefficient. A fatigue crack is also made in aluminum specimen to demonstrate these characteristics of the reflection and transmission of contact interfaces.