• Transactions of Materials Processing
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• v.18 no.6
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• pp.453-457
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• 2009

In this paper, plastic deformation behaviors of ESW105 and SCM435 steels are revealed by simulations and experiments. ESW105 is the special pre-heat-treated steel characterized by high initial yield strength and negligible strain-hardening behavior. The flow stresses of the two steels for large stain are calculated from tensile tests. Axial and lateral compressions of cylindrical bars are tested and simulated and the deformed shapes are compared to characterize the plastic deformation behaviors of the two materials. A forward extrusion process of a cylindrical bar is also simulated to reveal the difference. It has been shown that there are pretty much difference in plastic flow between ESW105 and SCM435 which causes from the difference in strain-hardening capability, implying that the experience-oriented design rules for common commercial materials may lead to failure in process design when the new material of ESW105 is applied without consideration of its plastic deformation behavior.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.48-51
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• 2009

In this paper, plastic deformation behaviors of ESW105 and SCM435 steels are revealed by simulations and experiments. ESW105 is the special pre-heat-treated steel characterized by high initial yield strength and negligible strain-hardening behavior. The flow stresses of the two steels for large stain are calculated from tensile tests. Axial and lateral compressions of cylindrical bars are tested and simulated and the deformed shapes are compared to characterize the plastic deformation behaviors of the two materials. A forward extrusion process of a cylindrical bar is also simulated to reveal the difference. It has been shown that there are pretty much difference in plastic flow between ESW105 and SCM435 which causes from the difference in strain-hardening capability, implying that the experience-oriented design rules for common commercial materials may lead to failure in process design when the new material of ESW105 is applied without consideration of its plastic deformation behavior.

• International Journal of Highway Engineering
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• v.4 no.4 s.14
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• pp.41-52
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• 2002

This study dealt with analysis of size effect of testing apparatus for Kim test which measures rut resistance characteristics of asphalt mixture under static loading. Two columns in different diameter with each column having different radios of round cut (Curvature) at the bottom were used for testing asphalt mixture. Deformation load ($P_{max}$) and deformation strength ($K_D$) were found to have relatively high correlation with rut depth and dynamic stability of asphalt concrete. Diameter of specimen was not a significant factor in this test. From the statistical correlation analysis with rutting properties, the radius of curvature and diameter of loading column were found to be important factor affecting the results of the test. Among the radios (r) of curvatures, r=0.5cm and 1.0cm showed much higher correlation than the column without curvature, and r=1.0cm being better between the two. The column with diameter of 4cm showed better correlation than diameter of 3cm. Therefore, the column of 4cm diameter with r=1.0cm was found to be the best among various apparatus sizes. Prediction models for rut depth and dynamic stability were developed for each aggregate mixture based on Kim test variables using SAS STEPWISE procedure. Therefore, if this test method is validated through further study, Kim test can be used for selecting asphalt mixture with the highest resistance against permanent deformation.

• Journal of the Korean Society for Heat Treatment
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• v.17 no.1
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• pp.23-28
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• 2004

In this work, the effect of Sc and Mm(misch metal) on the high temperature behavior of Al-Mg alloys was observed. Hardness was increased due to appearance of fine $Al_3Sc$ precipitates. The elongation of Al-Mg-Sc alloy at high temperature was higher than that of Al-Mg-Sc-Mm alloy because Al-Mg-Sc alloy has finer grain sizes than Al-Mg-Sc-Mm alloy. The strain rate sensitivity factor, "m" of Al-Mg-Sc and Al-Mg-Sc-Mm at $475^{\circ}C$ and $1{\times}10^{-2}s^{-1}$ were 0.33 and 0.46, respectively. The activation energy of Al-Mg-Sc and Al-Mg-Sc-Mm alloy for superplastic deformation was 133KJ/mol and 103KJ/mol respectively. The elongation of Al-Mg-Sc alloy at high temperature was decreased by the addition of Mm, but the strength at high temperatures and low strain rate was improved.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.5
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• pp.525-531
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• 2014

A cowl cross is a part of the car's instrument panel used to maintain the rigidity of the vehicle body side. The application of laser welding has the benefits of speed and thermal deformation compared to arc welding. An ultra-high strength steel sheet is used to reduce the weight of the vehicle body parts. Generally, formability of such a steel sheet is poor because its elongation is very low. For this reason, a method for cold forming of an ultra-high strength steel sheet is required. This paper describes how to improve the formability and weldability of the ultra-high strength steel sheet. Mechanical tests of this material were also performed to evaluate the welding properties of $CO_2$ (GMAW) and those of laser welding.

• Journal of the Korean Society for Advanced Composite Structures
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• v.3 no.3
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• pp.31-37
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• 2012

Under the huge seismic loads, there are too many risks about which high-rise buildings lost their lateral stiffness caused by plasticity on frame members. Because of earthquake is important cause to bring the collapes countinue to human's life, many reports examined these phenomenons in various angles. And some of them reported the high possibility about building collapse by deformation concentrations under huge earthquakes. For preventing these phenomenons, researchers suggest some items-such as adding damping devices or strengthen their ductility or stifness. This report suggests choose the method of strengthen building stiffness and suggests the alternative designs using high strength steel-SM570TMC, and provides the results of time-history analysis about the alternative designs for investigation.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.4
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• pp.278-287
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• 2023

This study aims to analyze and evaluate the structural strength of a 53ft Liquefied Natural Gas (LNG) tank container according to International Organization for Standardization (ISO) 1496-3, amidst growing global demand for LNG transportation. The research was conducted in two main stages: structural analysis using Finite Element Analysis (FEA) under various load conditions, and structural strength tests following ISO 1496-3 test procedures. The structural analysis was performed considering different loading conditions to assess the structural safety of the tank container. Calculated stresses were compared with allowable stress under specified load conditions. The structural strength tests were conducted at Mokpo National University's Subsea Umbilical cable Riser Flowline R&D Center, which provided a suitable testing environment. The study found that calculated stresses met the allowable stress under specified load conditions, confirming the structural safety of the tank container. Additionally, the maximum deformation and permanent deformation satisfied the design criteria for all test cases, indicating the container's structural strength meets requirements. The research also contributed valuable data for future structural strength tests of similar products and facilitated the development of safe and efficient LNG transportation solutions by developing effective test procedures in accordance with ISO 1496-3 standards.

• Korean Journal of Materials Research
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• v.30 no.2
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• pp.51-56
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• 2020

In this study, three kinds of metal chills such as SS400, AC4CH and brass, with different thicknesses of 40 ~ 80 mm, were applied for low pressure casting of Al-Si alloy to control cooling rate. The microstructural characteristics with increasing cooling rate were represented using factors including D₁, D₂, size of primary α phases and shape factor and size of eutectic Si. The tensile properties were investigated and additionally analyzed based on the microstructural characteristics. As the cooling rate increased, D₁, D₂, and sizes of primary α phases and eutectic Si apparently decreased and the shape factor of eutectic Si increased to over 0.8. The ultimate tensile strength (UTS) and yield strength (YS) increased with decreasing D₁, D₂, and size of primary α phases, while elongation increased with decreasing size of eutectic Si and concurrently increasing shape factor of eutectic Si. This indicated that the primary α phases and eutectic Si in Al-Si alloy were refined with increasing cooling rate, resulting in improvement of UTS and YS without sacrificing elongation. After the tensile test, preferential deformation of primary α phases was observed in the Al-Si alloy produced at higher cooling rates of more than 0.1 K/s.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.163-166
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• 2000

The production technology of high strength and toughness wear resistance steel involves attempt to application of severe wear parts for the construction machinery. A well balanced alloy content ensures that optimum tensile properties are achieved for the high strength. After high temperature deformation like as rolling or forging it has bainite microstructure and lower yield rato(under 80%) The effectiveness of the research approach is illustrated with experimental results on good steel cleanliness(O2 :12.2 ppm, 0,004% S, 0.008%, P nonmetalic inclusion dT: 0.10) and excellent mechanical properties (TS$\geq$140kgf/mm2 El $\geq$10% IV$\geq$20j/cm2) Therefore this should be wear resistance steel which develops high strength and high toughness without heat treatment

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.329-332
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• 2006

To study the effect of the macroscopic TVLEM(Three Vertical Line Element Model) which is developed in 2D, a bearing wall system is selected and 2D and 3D pushover analyses are carried out. In 2D model, the participating width of a flage wall to lateral resistance is modelled based on Paulay's effective width. From the comparisons of roof displacements, 2D model which uses the effective width of flange wall has better prediction and less analysis time than 3D model which has intrinsically the full width of the flange that causes higher stiffness and strength and shorter deformation capacity than 2D model.