• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.10
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• pp.809-815
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• 2014

The co-bonded dissimilar composite under a wide range of temperature change shows thermal distortion due to the differences in thermal expansion characteristics of the composite materials. Analysis of the thermal expansion characteristics of each composite is required for the design of co-bonded dissimilar composite structure with considering the shape distortion during the manufacturing process. In this work, digital image correlation (DIC) technique is introduced for measuring the thermal distortion characteristics of co-bonded dissimilar composite specimen, carbon/epoxy and silica/phenolic. The thermal distortion of co-bonded dissimilar composite specimen is numerically estimated and compared with the experiments. The estimated results is successfully validated using the measured results.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.12
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• pp.725-731
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• 2004

In this study, the three type hybrid interrupters according to the arrangement of the thermal expansion chamber and the puffer cylinder(they are called 'serial type', 'parallel/exchanged type', and 'parallel/separated type' respectively in this work) were designed and manufactured. This paper presents the tested results of the thermal recovery characteristics on the interrupters using a simplified synthetic test facility. The 'serial type' hybrid interrupter which is to obtain more easily the pressure rise for the thermal recovery compared with the others has the best capability in the thermal recovery characteristics. In order to investigate the stress on the operating mechanism, the distortion of the stroke wave in on-load test was examined to the stroke curve in no-load test. The biggest distortion was occurred in the 'parallel/exchanged type' hybrid interrupter. Finally, the small interruption capability on the three type interrupters was estimated by a theoretical form and the 'parallel/separated type' hybrid interrupter has the advantage of the others in the view of structure.

• Journal of Welding and Joining
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• v.32 no.4
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• pp.69-74
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• 2014

Welding distortions of large steel structures had mainly been estimated with some simplified formula obtained by lots of experience and numerical analyses for small steel structures. However, the large structures would have different characteristics of distortion with welding because of their own stiffness coming from the size itself. Therefore, in order to find some measures for preventing welding distortion of large structure, it is requite in advance to precisely analysis thermal stress and distortion during welding of the structure. Numerical analysis for larger structure has been known to take large amount of calculation time and have a poor convergency problem during the thermo-elasto-plastic calculation. In this study, a hybrid method is proposed to analysis the thermal stress and distortion of a large steel plate with the finite element analysis by incorporating with temperature distribution of the plate calculated by an analytical solution. The proposed method revealed that the thermo-mechanical analysis for welding of the large structure could be performed with a good convergence and produced precise results with much reduced time consumption.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.341-347
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• 2003

Single flighted screw extrusion is the most cost effective method for the production of film, sheet, pipe and the fundamental step in other processes including blow molding and injection molding The temperature and injection pressure in barrel play a very important role in quality of products. Because thermal distortion and displacement of barrel by temperature difference and injection pressure difference cause irregular resine melting and flow. In this paper thermal distortion and stress of barrel includes pressure and temperature distributions by finite element analysis to understand dynamic characteristics of barrel.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.11a
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• pp.212-220
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• 2000

Single flighted screw extrusion is the most cost effective method for the production of film, sheet, pipe and the fundamental step in other processes including blow molding and injection molding. The temperature of polymer melts and injection pressure play a very important role in the injection molding machine. Thermal distortion and displacement of screw by temperature difference and injection pressure difference cause adhesive wear by metal-to-metal contact. In this paper we analyze thermal distortion and stress of screw includes pressure and temperature distributions by finite element analysis to understand dynamic characteristics of screw.

• Journal of Welding and Joining
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• v.30 no.6
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• pp.120-125
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• 2012

Because ships and offshore structures have very large dimensions and complicated shapes, it is difficult to determine the deformation or internal stress in the structure by simple lab tests. Thus, a rigorous analysis by using the computer simulation technology is essential for obtaining their distortions by considering the entire production process characteristics. The rapid development of computer technology made it possible to analyze the heat transfer phenomena, deformation and phase transformation in the welded joint. For large shell structures, shell elements modeling contributed primarily to this development. But if a welding is done by multi-pass, shell elements whose thickness are unchangeable can hard to describe the local situation. Recently, it was researched how to introduce the imaginary temperature for V grooved multi-layer butt welding in strain-boundary method (a kind of shrinkage methodologies). In the present study, we formulated the imaginary temperature for the double bevel and double V groove by considering the thickness change of each pass through the bead and the thickness directions simultaneously and also demonstrated the feasibility of the formula by applying it to the thermal distortion analysis of the erection process of crane pedestal.

• KSTLE International Journal
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• v.1 no.2
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• pp.95-100
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• 2000

The thermal behaviors of disk-pad braking models has been analyzed for a high-speed train brake system using the coupled thermal-mechanical analysis technique. The temperature distribution, thermal distortion, and contact stress in the disk-pads contact model have been investigated as functions of the convective heat transfer rate. The FEM results indicate that multiple spot type pads show more stabilized thermal characteristics compared with those of the flat type pads for the increased convective heat transfer rate. The maximum contact stress for a friction pad loaded against a rubbing disk was occurred on the edge of the pad at the disk-pad interface.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.1
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• pp.48-59
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• 2018

This paper is mainly concerned with developing the formulae of predicting thermal deformation of steel plate due to multi-line heating. By investigating the results of line heating test and numerical analysis, reasonable heat flux model has been defined. Formulae of predicting the transverse shrinkage and the angular distortion as the dominant thermal deformation types in plate forming by line heating have been derived based on the results of line heating test and numerical analysis with varying plate thickness, heating speed and distance between torches. This paper illustrates how the derived formulae are used in investigating the effect of multi-line heating upon the thermal deformation and how they can be used in defining the limit distance with that there is no interacted effect between torches. This paper ends with describing the extension of the present study.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.122-129
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• 2004

Finite element analysis was performed to analyze structural safety of a new heavy-duty direct injection diesel engine. A half section of the in-line 6-cylinder engine was selected as a computational domain. A mapping method was used to project heat transfer coefficients from CFD results of engine coolant flow onto the FE model. The accurate setting of thermal boundary condition on the FE model was expected to result in improved prediction of temperature, cylinder bore distortion, and stresses. Characteristics of high cycle fatigue were investigated by assuming the engine was operated under the following five loading conditions repeatedly; assembly force, assembly force with thermal loading, alternating maximum gas pressure loading at each cylinder combined with assembly force and thermal loading. Distribution of fatigue safety factor was calculated by using it Haigh diagram in which the maximum and the minimum stresses were selected from the five loading cases.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.57-57
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• 2010

For thin panel welded structure, the various welding distortions were found due to the low resistance against welding deformation. Especially, buckling distortion induced in the thin panel welded structure produce severe problems related to cost in production stage and safety in service life. So, many researches including mechanical and thermal tensioning method for preventing the occurrence of buckling distortion in the production stage have been performed. The purpose of this study is to identify the behavior of longitudinal residual stress at the SA butt weldment with thin plate of 6mm thickness under tension load by 3 dimensional FEA. For it, mesh design for 3D FEA was constructed with 20 nodes brick element for butt weldment and 8 nodes shell element for base metal. According to FEA results, the longitudinal compressive strain inducing tensile residual stress at the butt weldment decreased. It was because the compressive thermal strain in way of weldment was reduced by tension load. The control effect of residual stress increased with an increase in tension load. So, if the amount of tension load applied to the weldment exceeds 1.5 times of longitudinal shrinkage force, the amount of longitudinal residual stress decreased below the critical value inducing the buckling distortion at the SA butt weldment. Its validity was verified by experiment.