• Title, Summary, Keyword: Mechanical & Thermal properties

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Thermal and Mechanical Properties of Structural Steel SN400 at Elevated Temperatures

  • Choi, In-Rak;Chung, Kyung-Soo;Lee, Hyerin
    • International journal of steel structures
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    • v.17 no.3
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    • pp.999-1007
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    • 2017
  • The accurate estimation of thermal and mechanical properties is a prerequisite for the reliable fire-resistant design of steel structures, considering that steel is used as one of the main materials for buildings due to fast construction, light weight, and high seismic resistance. For this reason, an experimental study was performed to examine the thermal and mechanical properties of SN400, one of structural steels for buildings, at various temperatures ranging from 20 to $900^{\circ}C$. For thermal properties, thermal conductivity, specific heat, and expansion of SN400 were investigated. For mechanical properties, steady-state tension coupon tests were conducted. The yield strength, elastic modulus, ultimate tensile strength, and stress-strain relationships of SN400 were investigated. The measured properties of SN400 were compared with those of other mild-strength steels and predictions by current design guidelines.

Prediction of Thermal and Elastic Properties of Honeycomb Sandwich Plate for Analysis of Thermal Deformation (열변형 해석을 위한 허니컴 샌드위치 평판의 열 및 탄성 물성치 예측에 관한 연구)

  • Hong, Seok Min;Lee, Jang Il;Byun, Jae Ki;Choi, Young Don
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.38 no.4
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    • pp.347-355
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    • 2014
  • Thermal problems that are directly related to the lifetime of an electronic device are becoming increasingly important owing to the miniaturization of electronic devices. To solve thermal problems, it is essential to study thermal stability through thermal diffusion and insulation. A honeycomb sandwich plate has anisotropic thermal conductivity. To analyze the thermal deformation and temperature distribution of a system that employs a honeycomb sandwich plate, the thermal and elastic properties need to be determined. In this study, the thermal and elastic properties of a honeycomb sandwich plate, such as thermal conductivity, coefficient of thermal expansion, elastic modulus, Poisson's ratio, and shear modulus, are predicted. The properties of a honeycomb sandwich plate vary according to the hexagon size, thickness, and material properties.

Determination of Relationship between Thermal and Mechanical Properties of Wood Material

  • Ozcan, Cemal;Korkmaz, Mustafa
    • Journal of the Korean Wood Science and Technology
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    • v.47 no.4
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    • pp.408-417
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    • 2019
  • Non-destructive test techniques are becoming increasingly important for assessment and maintenance. These techniques are very useful for assessment of materials such as wood, whose performance can vary considerably depending on the conditions of use. It is possible to estimate some mechanical properties of a material by determining the movement of energy through the material with the help of these techniques. In this study, it was investigated whether the wood material could be tested nondestructively by the heat energy produced by a source. The correlations between the thermal conductivity and mechanical properties of Scots pine (Pinus sylvestris L.) and sessile oak (Quercus petraea L.) woods were investigated. The thermal conductivity (TC), density, modulus of rupture (MOR), compression strength (CS), and modulus of elasticity (MOE) values of samples were measured according to the related standards and these values were correlated with each other. The linear and multiple regression tests were employed to determine the correlation between thermal conductivity and mechanical properties. The results showed that there is a very strong correlation between thermal conductivity and both density and MOR values. However, the correlations between TC and both MOE and CS were moderate. The results of this study suggest that the thermal conductivity value can be used to estimate the density and some mechanical properties of wood.

Effect of Thermal Pressing Temperature on the Mechanical and Material Properties of Electro-spun Polyacrylonitrile Nano-fibrous Separator (열압착 온도가 전기방사 Polyacrylonitrile 분리막의 기계적 강도 및 물성치에 미치는 영향)

  • Kim, Minchoel;Ko, Tae Jo;Arifeen, Waqas Ul;Dong, Ting
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.18 no.4
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    • pp.109-116
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    • 2019
  • The mechanical deformation of a battery separator causes internal short-circuiting of the cathode - anode, which directly affects the explosion/ignition of batteries. To increase the mechanical properties of the separator fabricated by electro-spinning, use of a thermal pressing method is inevitable. Therefore, this research aims to maximize the mechanical strength of a porous separator by finding the proper thermal press temperatures given to Electro-spun Polyacrylonitrile (PAN) nanofibers. The different thermal press temperatures $25^{\circ}C$, $50^{\circ}C$, $75^{\circ}C$, and $100^{\circ}C$ were applied to the electro-spun fiber at 30 MPa pressure for one hour. The higher the temperature, the higher the resultant tensile strength; however, a higher temperature also lowered the strain and porosity. Thus, the membrane thermal pressed at $50^{\circ}C$ showed the best mechanical properties and the second highest porosity. Using the data, $50^{\circ}C$ was judged as the best thermal pressing temperature in terms of performance.

Thermal and Mechanical Properties of Electro-Slag Cast Steel for Hot Working Tools

  • Moon Young Hoon;Kang Boo Hyun;Van Tyne Chester J.
    • Journal of Mechanical Science and Technology
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    • v.19 no.2
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    • pp.496-504
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    • 2005
  • The thermal and mechanical properties of an electro-slag cast steel of a similar chemical composition with an AISI-6F2 steel are investigated and compared with a forged AISI-6F2 steel. AISI-6F2 is a hot-working tool steel. Electro-slag casting (ESC) is a method of producing ingots in a water-cooled metal mold by the heat generated in an electrically conductive slag when current passes through a consumable electrode. The ESC method provides the possibility of producing material for the high quality hot-working tools and ingots directly into a desirable shape. In the present study, the thermal and mechanical properties of yield strength, tensile strength, hardness, impact toughness, wear resistance, thermal fatigue resistance, and thermal shock resistance for electro-slag cast and forged steel are experimentally measured for both annealed and quenched and tempered heat treatment conditions. It has been found that the electro-slag cast steel has comparable thermal and mechanical properties to the forged steel.

Influence of Dilauroyl Peroxide on Mechanical and Thermal Properties of Different Polypropylene Matrices (Dilauroyl Peroxide의 PP에 대한 기계적, 열적 성질 변화)

  • Sirin, Kamil;Yavuz, Mesut;Canli, Murat
    • Polymer(Korea)
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    • v.39 no.2
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    • pp.200-209
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    • 2015
  • In this study, the influence of dilauroyl peroxide on mechanical and thermal properties of different polypropylene (PP) matrices was investigated. Polypropylene matrices, different molecular weight isotactic PP containing 0.01, 0.02, 0.04, 0.06, 0.08, and 0.1 wt% of dilauroyl peroxide (DLP) were prepared by using a single-screw extruder. The effect of the visbreaking agent (DLP) on mechanical, physical, thermal and morphological properties of different molecular weight PP had been studied. Mechanical properties (tensile strength at break point, at yield and elongation at break point), melt flow index (MFI), scanning electron microscope (SEM) and differential scanning calorimetric (DSC) analyses of these matrices were examined. Melting ($T_m$) and crystallization ($T_c$) temperatures, crystallinity ratio (%) and enthalpies were determined. The microstructure of isotactic polypropylene matrix was investigated by scanning electron microscopy (SEM). From SEM analysis, it was observed that the surface disorder increased by the increasing amount of DLP. As a result of DSC analyses, the crystallinity ratio of the PP matrices has varied between 1.64-7.27%. Mechanical properties of the matrices have been improved. Particularly, the mechanical tests of PP have given interesting results when compounded with 0.06-0.08 wt% dilauroyl peroxide (DLP). Mechanical properties and thermal decomposition processes were all changed by increasing the amount of DLP in the matrix structure.

High Temperature Thermo-mechanical Properties of HfC Reinforced Tungsten Matrix Composites

  • Umer, Malik Adeel;Lee, Dong Ju;Ryu, Ho Jin;Hong, Soon Hyung
    • Composites Research
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    • v.28 no.6
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    • pp.366-371
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    • 2015
  • In order to improve the mechanical properties of tungsten at room and elevated temperature, hafnium carbide (HfC) reinforced tungsten matrix composites were prepared using the spark plasma sintering technique. The effect of HfC content on the compressive strength and flexural strength of the tungsten composites was investigated. Mechanical properties of the composites were also measured at elevated temperatures and their trends, with varying reinforcement volume fraction, were studied. The effect of reinforcement fraction on the thermal properties of the composites was investigated. The thermal conductivity and diffusivity of the composites decreased with increasing temperature and reinforcement volume fraction. An inherently low thermal conductivity of the reinforcement as well as interfacial losses was responsible for lower values of thermal conductivity of the composites. Values of coefficient of thermal expansion of the composites were observed to increase with HfC volume fraction.

Evaluation of Characteristic for SS400 and STS304 steel by Weld Thermal Cycle Simulation - 1st Report : on the Mechanical Properties and Microstructure (용접열사이클 재현에 의한 SS400강 및 STS304강의 특성 평가 - 제1보 : 기계적 특성 및 조직)

  • Ahn, Seok-Hwan;Jeong, Jeong-Hwan;Nam, Ki-Woo
    • Journal of Ocean Engineering and Technology
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    • v.19 no.6
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    • pp.64-71
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    • 2005
  • The welding methods have been applied to the most structural products used in the automobile, ship construction, and construction. The structure steel must have sufficient strength of structure; However, the mechanical properties of the welded part changes when it is welded. Therefore, the stability or life of the structure may be affected by the changed mechanical properties. The mechanical properties of the welded part must be examined in order to ensure the safety of structure. In this research, the SS400 steel and the STS304 steel were used to estimate the mechanical properties of the HAZ by weld thermal cycle simulation. In this study, the materials were used to examine the weld thermal cycle simulation characteristic, under two conditions: the drawing with diameter of $\Phi$10 and the residual stress removal treatment. To examine the mechanical properties by the weld thermal cycle simulation, the tensile test was carried out in room temperature. The crosshead speed was lmm/min.

Evaluation of mechanical and thermal properties of insulation materials for HTS power devices at liquid nitrogen temperature

  • Shin, Hyung-Seop;Diaz, Mark Angelo
    • Progress in Superconductivity and Cryogenics
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    • v.19 no.2
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    • pp.53-57
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    • 2017
  • In superconducting power devices including power cables in which high temperature superconducting (HTS) tapes are utilized, a reliable electrical insulation should be achieved for its maximum performance. For an efficient design of HTS superconducting devices, a comparative evaluation of the mechanical and thermal propperties for various insulation materials at cryogenic temperatures is required. Especially, in the process of the property evaluation of the sheet-shaped insulation materials, anisotropy according to the machining direction should be considered because the mechanical and thermal properties are significantly influenced by the sample orientation. In this study, the cryogenic thermal and mechanical properties of various insulation material sheets such as PPLP, Cryoflex, Teflon, and Kapton were determined considering sample orientation. All samples tested at cryogenic temperature showed significantly higher tensile strength as compared with that of room temperature. The ultimate tensile strength at both temperature conditions significantly depended upon the sample orientation. The thermal properties of the insulation materials exhibited a slight difference among samples depending on the orientation: for the PPLP and Cryoflex, the CD orientation showed larger thermal contraction up to 77 K as compared to the MD one. MD samples in PPLP and Cryoflex showed a lower CTE and thermal contraction which made it more promising as an insulation material due to its comparable CTE with HTS CC tapes.

Thermal and Mechanical Properties of Ceramic Coated Al Bus Bar (세라믹 코팅 Al 부스바의 열적·기계적 특성)

  • Kwag, Dong-Soon;Baek, Seung-Myeong;Kwak, Min Hwan
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.66 no.11
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    • pp.1651-1656
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    • 2017
  • This paper deals with the thermal and mechanical properties of ceramic coating material for bus bars. A ceramic coated samples were prepared for the mechanical properties test. There are two types of samples. One is a square shape and the other is a busbar shape. Each sample was deteriorated for 30 days to compare the thermal and mechanical properties with the non-degraded samples. Two thermal properties tests are TGA and flammability tests, and four mechanical properties tests are drop impact test, cross cut, tensile test, and bend test. The ceramic coating material was never damaged by impact and did not separate from aluminum in the cross cut test. In the tensile test, the breakage of the insulating material did not occur until aluminum fractured, and the breakage of the insulating material did not occur until the maximum load in the bending test. The decomposition temperature (melting point) of the ceramic coating material was higher than that of other epoxy insulators. This ceramic coating material is nonflammable and it has excellent fire stability.