• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.695-696
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• 2008

This paper deals with the reduction of DC component of cogging toruqe by using the heat treatment of the stator core. The stator core is made of electrical steel sheared by the punching die. From the punching process, large mechanical stress at the edge of stator tooth induces significant plastic and elastic deformation and influences magnetic properties. Then, these phenomenon in the sheared region has influence on the magnetic unbalance in the air-gap of motor. This paper investigated the effect of the punching process on the magnetization process and the mechanical deformation and proposed the stress relief annealing method for the reduction of friction torque among one of motor characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.355-357
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• 1998

BSCCO-2223 superconducting tape made by PIT method can be influenced in the critical characteristics by the heat treatment and the mechanical processing. Particulary, it has been reported that the mechanical deformation affects the core density, texture of the core, sausaging and so on. Therefore the accurate control of the deformation process is very important to achieve high J$\sub$c/. In this study, we measured the J$\sub$c/ variation for different rolling reduction rate and investigated the change of core shape to compare the formation of sausaging.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.316-319
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• 2008

The L-bending of inner-structure bonded sandwich sheet metal is examined by using a bending die attached to the material testing machine. The specimen is composed of top and bottom layers and a middle layer of pyramid-core structure and each layer is bonded by brazing. The variables chosen for experiments were clearance between punch and die, location of bend line on the specimen surface and clamping type of specimen during L-bending. Effects of these variables on deformation of specimen around die-corner radius were investigated. It was shown that the irregular shapes of recess are formed in the inner layer of bended parts and they greatly depend on working conditions.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.320-323
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• 2008

In this study, a macroscopic approach was carried out to gain insight into the bending mechanism of metallic sandwich plates. Shear force-punch stroke curves for various clearances were analytically derived for mild steel (CSP 1N) sandwich plates with the total thickness of 3 mm and 0.5 mm face sheets. As the clearance increases, shear force of the inner structures and sensitivity of punch stroke decrease. These data are useful to derive a criterion of judgment for core shear failure and de-bonding failure during U-bending.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.560-563
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• 2008

A condensed model is proposed for the simulation of forming of sandwich sheet with pyramid core. A corresponding finite element analysis for L-type bending is carried out to prove the accuracy and the effectiveness. Simulation results are compared with those of experiment. Deformation shape and post-buckling behavior by simulation are in good agreement with those of experiment for the considerable range of deformation. From the comparison of force-displacement curve, it is shown that the proposed model shows good prediction of the forming force compared to the experiment. Thus, the effectiveness of the proposed method is sufficiently demonstrated.

• Journal of Welding and Joining
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• v.21 no.4
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• pp.80-86
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• 2003

Arc-spot welding is generally used in joining of precise parts such as case and core in electric compressor. It is important to control joining deformation in electric compressor because clearance control of micrometer order is needed for excellent airtightness and anti-nose. The countermeasures for this deformation in field have mainly been dependent on rule of try and error by operator's experience because of productivities. For control this deformation problem without influence on productivities, development of exact simulation model should be needed. In this study, on the basis of previous study, the analysis model io predict deformation of precise order in arc-spot welded structure with non-uniform stiffness is brought up through feedback and tuning between monitoring data and analysis results. For this, deformation monitoring system was built and boundary condition considering mechanical melting temperature was applied.

• Transactions of Materials Processing
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• v.6 no.3
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• pp.221-226
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• 1997

Chevron crack in cold extrusion has been studied in view of deformation conditions and material characteristics. There is V formed chevron crack is occasionally occurred in core part of shaft by multistage free extrusion. Although many research results were reported and theoretical analyses were accompanied, in this study we discussed practical method to prevent chevron crack in the field of working conditions and material characteristics. We have found that chevron crack is eliminated under condition of high hydrostatic state in deformation and decreased segregation, refinement of micro structure of materials.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.5
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• pp.82-86
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• 2013

The automotive weather strip has the functions isolating of dust, water, noise and vibration from outside. The core of weather strip is made of steel with stiffness. By using the wire formed as the core of weather strip, weight can be reduced as much as 35% by comparing with existing steel core. For this reason, forming wire is necessary to keep the zigzag shape as it is. The deformation which is occurred during forming process can be predicted and it can be used in case of manufacturing dies through CAE. In this paper, rolling process conditions are deduced and the springback amount is predicted after rolling process by using the simulation. The springback amount of product is measured by using optical microscope, and measurement result is compared with the simulation result of springback as the same condition. The suitable gap between dies to compensate springback after rolling process is predicted through simulation and it is used for manufacturing dies.

• Design & Manufacturing
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• v.11 no.3
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• pp.29-34
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• 2017

Increased demand for parts with micro-pattern structure made of metals, ceramics, and composites in various fields such as medical ultrasonic sensors, CT collimators, and ultra-small actuator parts. Micro powder injection molding (PIM) is a technology for manufacturing micro size, high volume, complex, precision, net-shape components from either metal or ceramic powder. In the present study, a standard mold with a variable insert core capable of producing various micro patterns was investigated. An injection molding test was performed on a standard mold using a line type micro-pattern core having an aspect ratio of 2, a slenderness ratio of 70, a pattern size of $200{\mu}m$, and a pattern spacing of $150{\mu}m$. During the filling process, the deformation of the mold with large aspect ratio and slenderness ratio was analyzed by the experiment and the numerical simulation according to the position of the gate. We proposed a mold structure that minimizes mold deformation by gate modification and enables uniform pattern filling behavior.

• Journal of Korean Association for Spatial Structures
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• v.23 no.1
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• pp.45-52
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• 2023

This study proposes an RCS composite damping device that can achieve seismic reinforcement of existing buildings by dissipating energy by inelastic deformation. A series of experiments assessing the performances of the rubber core pad, hysteretic steel slit damping device, and hybrid RCS damping device were conducted. The results showed that the ratios of the deviations to the mean values satisfied the domestic damping-device conformity condition for the load at maximum device displacement in each direction, at the maximum force and minimum force at zero displacement, as well as the hysteresis curve area. In addition, three analysis models based on load-displacement characteristics were proposed for application to seismic reinforcement design. In addition, the validity of the three proposed models was confirmed, as they simulated the experimental results well. Meanwhile, as the shear deformation of the rubber-core pad increased, the hysteretic behavior of super-elasticity greatly increased the horizontal force of the damping device. Therefore, limiting the allowable displacement during design is deemed to be necessary.