• Structural Engineering and Mechanics
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• v.53 no.3
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• pp.429-442
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• 2015

The measurement from the indentation process depends on the amount of pile-up or sink-in around the contact impressions. In this paper, finite element concept is utilized to study the pile-up and sink-in behaviour for the wide range of materials with different young's modulus, yield stresses, strain-hardening exponents and coefficient of friction values. The exact indentation model is created by using the two dimensional axisymmetrical model for simulating the spherical indentation process on the lines of Taljat and Pharr (2004) work. The result shows that during spherical indentation process the amount of pile-up is greatly influenced by the strain hardening exponents in addition to other material properties and depth of penetration. The numerical results from the finite element analysis are also validated using the exact multilinear material properties obtained from the tensile testing for the materials like mild steel, brass and aluminium.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.120-122
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• 2006

This study deals with characterizations of microstructure and wear performance of a cladding layer, product on 1.9 mm-thick mild steel plate by the electric resistance welding, of composite metal powder of Coarse WC-6.5%Co and high carbon alloy(SHA). The cladding layer was examined and tested fur microstructural features, chemical composition, hardness, wear performance and wear mechanism. The cladding layer have two different matrix were observed by an optical microscope and EPMA. The one was the coarse WC-6.5Co structure. The other was the melted SHA with surrounding the WC-6.5Co structure. The hardness of WC-6.5Co was 1210HV. The hardness of SHA was 640HV. In comparison by wear rate, the cladding layer showed the remarkable wear performance that was 15 times of SM490 and about 62% of D2.

• Structural Engineering and Mechanics
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• v.13 no.6
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• pp.591-614
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• 2002

This paper presents experimental and numerical analyses of the thermomechanical behaviour that takes place in SAE1020 mild steel cylindrical specimens during the conventional tensile test. A set of experiments has been carried out in order to obtain the stress-strain curve and the diameter evolution at the neck which allow, in turn, to derive the elastic and hardening parameters characterizing the material response. Temperature evolutions have also been measured for a high strain rate situation. Moreover, a finite element large strain thermoelastoplasticity-based formulation is proposed and used to simulate the deformation process during the whole test. Some important aspects of this formulation are discussed. Finally, the results provided by the simulation are experimentally validated.

• Journal of Welding and Joining
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• v.9 no.3
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• pp.18-25
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• 1991

The purpose of this paper was to investigate the effect of deposition configuration on the mechanical properties of the flame sprayed titania ceramic coating. The sprayed deposition configuration was made in different five types with titania ceramic and Ni-base alloy on the mild steel substrate. The composite coating exhibited superior mechanical properties such as hardness, adhesive strength, thermal shock resistance and corrosion resistance, whereas the mixed coating proved to be more resistant to erosion. Especially graded coating, which consist of Ni-base alloy undercost, intermediate grade coat and titania ceramic overcost, showed excellent mechanical properties.

• Journal of Advanced Marine Engineering and Technology
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• v.15 no.3
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• pp.39-44
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• 1991

The purpose of this investigation is to examine the effects of spraying conditions on the mechanical properties of flame-sprayed titania ceramic coating layer. Titania ceramic was sprayed onto the mild steel substrate under the various spraying conditions. Spraying distances were 100, 150, 200, 250mm respectively and pinch air pressures were 0.2 0.3, 0.4 MPa at each spraying distance. The mechanical properties such as microhardness, adhesive strength and erosion wear resistance were tested for the specimens sprayed under the various spraying conditions above mentioned. The optimum operational conditions obtained through the experimental results were 150mm of spraying distance and 0.3 MPa of pinch air pressure.

• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.3
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• pp.286-293
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• 1983

This study measures polar compressive thickness strain and radius of curvature of the bulge through Moire' method in bulge test. Hill's and Alexander's bulge theories, instability conditions derived by Swift's, Hill's, Alexander's and wang's theories, are also investigated, compared with Moire' experimental results. In order to review and compare with Hill's and Alexander's bulge theories, the relationships between radius of curvature of the bulge and polar height, between polar compressive thickness strain and polar height, are used. Mild steel, soft copper and commercial pure aluminum are used in Moire' experiment. According to this study, Hill's and Alexander's bulge theories, instability conditions derived by Swift's, Hill's, Alexander's and Wang's theories are agreement to Moire' experiment results.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.1
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• pp.33-38
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• 2012

An experimental study was carried out to observe the characteristics of impingement of assist gas from a rectangular supersonic nozzle on kerf surface in laser machining. A micro-scale supersonic (Mach number 2.0) rectangular nozzle system was designed and fabricated for the purposes, and hot tests of the performance of the nozzle system was proceeded in the ITI corporation laboratory. For various related parameters such as laser powers, nozzle pressures and cutting speeds, the quality of the frontal view of cut edge surfaces was observed by a microscope. In the study, it was shown that the application of the present micro-rectangular supersonic nozzle in an off-axis configuration made it possible to cut a mild steel, by combinations of relatively low laser - powers, large standoff distances, and assist gas with no oxygen, which was not achieved by conventional laser cutting processes.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.11
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• pp.63-73
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• 1995

A mechanistic force system model considering the flank wear for the face milling process has been developed. The model predicts variation of the cutting forces according to flank wear in face milling over a range of cutting conditions, cutter geometries and cutting process geometries including relative positions of cutter to workpiece and rounouts. Flycutting and multitoth cutting teste were conducted on SS41 mild steel with sintered carbide tool. In order to verify the mechanistic force model considering the flank wear of cutting tools, a series of experiments was performed with single and multitooth cutters in various cutting conditions. The results show good agreement between the predicted and measured cutting force profiles and magnitudes in time and frequency domains.

• Journal of Power System Engineering
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• v.3 no.2
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• pp.89-97
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• 1999

In this paper the forming simulations of ellipse bulge have been researched by using $PAM-STAMP_{TM}$ to estimate the sheet metal forming and the plastic deformation characteristic of ellipse bulge. Thin elliptical diaphragms of brass, copper, aluminum, and mild steel are bulged in elliptical dies having aspect ratios of 1.33 and 2. In order to compare the simulation results with the experiment and ellipse bulge's theory derived by using Johnson and Duncan's theory, the relations of hydraulic pressure and polar height, polar thickness strain and polar height, were compared. According to this study, the results of simulation and ellipse bulge's theory derived by using Johnson and Duncan's theory, and the bursting pressure and the bursting polar height are good agreement to the experiment. So, the results of simulation by using $PAM-STAMP_{TM}$ and the ellipse bulge's theory will give engineers good information to make assessment the formability and plastic deformation characteristic of hydraulic ellipse bulge test.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.763-766
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• 2000

The Rapid Prototyping and Tooling technology has been developed. However, most commercial ones currently use resins or waxes as the raw materials. These days. the direct metal deposition methods are researched as a true rapid prototyping and tooling technology. A fundamental study on rapid prototyping and tooling with wire welding technology using $CO_2$ laser radiation was carried out in this paper. The main focus is to develop a simple commercial rapid prototyping and tooling system with the exiting laser welding technology. The process is investigated as a function of laser parameters and process variables. Basic parts were fabricated as out-put and their microstructure, hardness and tensile strength are examined for the reliability. In addition, Its advantages and disadvantages are discussed as a rapid prototyping and tooling system.