• Title/Summary/Keyword: Physical·Mechanical property

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Disjoining Pressures of Nanoscale Thin Films on Solid Substrate (고체 면에 흡착된 박막에서의 분리압력 특성에 관한 연구)

  • Han, Min-Sub
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.2
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    • pp.101-106
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    • 2009
  • The disjoining pressure is an important physical property in modeling the small-scale transport phenomena on thin film. It is a very useful definition in characterizing the non-continuum effects that are not negligible in heat and mass transport of the film thinner than submicro-scales. We present the calculated values of disjoining pressure of He, Kr and Xe thin films absorbed on graphite substrate using Molecular Dynamics Simulation (MD). The disjoining pressure is accurately calculated in the resolution of a molecular scale of the film thickness. The characteristics of the pressure are discussed regarding the molecular nature of the fluid system such as molecular diameter and intermolecular interaction parameters. The MD results are also compared with those based on the continuum approximation of the slab-like density profile and the results on other novel gases in the previous study. The discrepancies of the continuum model with MD results are shown in all three configurations and discussed in the view point of molecular features.

Prediction of Anisotropy and Formability of Lithium-ion Battery Pouch Sheet using Non-quadratic Yield Function (비이차 비등방 항복함수를 이용한 리튬-이온 배터리 파우치의 이방성 및 성형성 예측)

  • J. S. Kim;C. M. Moon;H.R. Lee;M. G. Lee
    • Transactions of Materials Processing
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    • v.32 no.3
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    • pp.136-144
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    • 2023
  • This study analyzed the mechanical behavior of lithium-ion battery pouch material and predicted its formability. A homogenization method was used to evaluate the physical properties of the pouch, and a new hardening model was developed. The yield function for the plastic model was optimized, and the anisotropic property was determined. Also, the forming limits were measured and predicted using the M-K forming limit diagram. Finally, a square cup drawing experiment confirmed the accuracy of the measured mechanical properties and the formability calculation.

Physical and Mechanical Properties of Heat-treated Domestic Yellow Poplar (백합나무 열처리재의 물리 및 역학적 특성)

  • Kim, Kwang-Mo;Park, Jung-Hwan;Park, Byoung-Soo;Son, Dong-Won;Park, Joo-Saeng;Kim, Wun-Sub;Kim, Byoung-Nam;Shim, Sang-Ro
    • Journal of the Korean Wood Science and Technology
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    • v.38 no.1
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    • pp.17-26
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    • 2010
  • Recently, yellow poplar (Liriodendron tulipifera L.) is getting attention in Korea due to the fast growing and high yield and quality of lumber. But, it is thought that the color difference between heartwood and sapwood may restrict the practical use of it. This study was aimed to enhance the value of yellow poplar lumber by the color control using high temperature heat-treatment, which had been tried for domestic cedar (Kim et al., 2009). The material properties including surface color of yellow poplar lumber were evaluated according to heat treatment conditions. The difference of color between sapwood and heartwood could be reduced by heat treatment at a temperature about $200^{\circ}C$. Long heating time was more effective in reducing the difference. The Equilibrium Moisture Content (EMC) of heat-treated wood was as low as 50 percent of the control. The result obviously indicates that heat-treated wood is more dimensionally stable in the change of moisture condition. The durability against wood rotting fungi also increased by the heat-treated, but it was not so effective as the case of cedar. The changes of mechanical properties of heat-treated yellow poplar were very similar to that of heat-treated cedar. In order to develop new use of heat-treated yellow poplar, the changes of mechanical properties should be considered. There were no significant changes in microscopic structure which may cause changes in mechanical properties. Further study of heat-treated wood is needed to scrutinize the causes of changes of material properties.

Analysis of the Physical Properties of the Conductive Paste according to the Type of Binder Resin and Simulation of Mechanical Properties according to Ag Flake Volume Fraction (바인더 수지 종류에 따른 도전성 페이스트의 물성 분석 및 Ag flake 부피 분율에 따른 기계적 특성 시뮬레이션 연구)

  • Sim, Ji-Hyun;Yun, Hyeon-Seong;Yu, Seong-Hun;Park, Jong-Su;Jeon, Seong-Min;Bae, Jin-Seok
    • Composites Research
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    • v.35 no.2
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    • pp.69-74
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    • 2022
  • In this study, the conductive paste used in a wide range such as wiring in the electronic packaging field, the automobile industry, and electronic products is manufactured under various process conditions due to the simplicity of the process, and then the thermal, mechanical, and electrical characteristics are analyzed and simulation studies are conducted to optimize the process. to establish the conditions of the conductive paste manufacturing process. First, a conductive paste was prepared by setting various types of binder resin, an essential component of the conductive paste, and characteristics such as thermal conductivity, tensile strength, and elongation were analyzed. Among the binder resins, the conductive paste applied with a flexible epoxy material had the best physical properties, and a simulation study was conducted based on the physical property data base of the conductive face. As a result of the simulation, the best physical properties were exhibited when the Ag flake volume fraction was 60%.

Measurement of Mechanical and Physical Properties of Pepper for Particle Behavior Analysis

  • Nam, Ju-Seok;Byun, Jun-Hee;Kim, Tae-Hyeong;Kim, Myoung-Ho;Kim, Dae-Cheol
    • Journal of Biosystems Engineering
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    • v.43 no.3
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    • pp.173-184
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    • 2018
  • Purpose: This study was conducted to investigate the mechanical and physical properties of a Korean red pepper variety for particle behavior analysis. Methods: Poisson's ratio, modulus of elasticity, shear modulus, density, coefficient of restitution, and coefficient of friction were derived for "AR Legend," which is a domestic pepper variety. The modulus of elasticity and Poisson's ratio were measured through a compression test using a texture analyzer. The shear modulus was calculated from the modulus of elasticity and Poisson's ratio. The density was measured using a water pycnometer method. The coefficient of restitution was measured using a collision test, and the static and dynamic friction coefficients were measured using a inclined plane test. Each test was repeated 3-5 times except for density measurement, and the results were analyzed using mean values. Results: Poisson's ratios for the pepper fruit and pepper stem were 0.295 and 0.291, respectively. Elastic moduli of the pepper fruit and pepper stem were $1.152{\times}10^7Pa$ and $3.295{\times}10^7Pa$, respectively, and the shear moduli of the pepper fruit and pepper stem were $4.624{\times}10^6Pa$ and $1.276{\times}10^7Pa$, respectively. The density of the pepper fruit and the pepper stem were $601.8kg/m^3$ and $980.4kg/m^3$, respectively. The restitution coefficients between pepper fruits, pepper stems, a pepper fruit and a pepper stem, a pepper fruit and plastic, and a pepper stem and plastic were 0.383, 0.218, 0.277, 0.399, and 0.148, respectively. The coefficients of static friction between pepper fruits, pepper stems, a pepper fruit and a pepper stem, a pepper fruit and plastic, and a pepper stem and plastic were 0.455, 0.332, 0.306, 0.364, and 0.404, respectively. The coefficients of dynamic friction between a pepper fruit and plastic and a pepper stem and plastic were 0.043 and 0.034, respectively.

Impact and Delamination Failure of Multiscale Carbon Nanotube-Fiber Reinforced Polymer Composites: A Review

  • Khan, Shafi Ullah;Kim, Jang-Kyo
    • International Journal of Aeronautical and Space Sciences
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    • v.12 no.2
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    • pp.115-133
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    • 2011
  • Fiber reinforced polymer composites (FRPs) are being increasingly used for a wide range of engineering applications owing to their high specific strength and stiffness. However, their through-the-thickness performance lacks some of the most demanding physical and mechanical property requirements for structural applications, such as aerospace vehicles and military components. Carbon nanotubes (CNTs) and carbon nanofibers (CNFs), due to their excellent mechanical, thermal and electrical properties, offer great promise to improve the weak properties in the thickness direction and impart multi-functionality without substantial weight addition to FRPs. This paper reviews the progress made to date on i) the techniques developed for integration of CNTs/ CNFs into FRPs, and ii) the effects of the addition of these nanofillers on the interlaminar properties, such as such interlaminar shear strength, interlaminar fracture toughness and impact damage resistance and tolerance, of FRPs. The key challenges and future prospects in the development of multiscale CNT-FRP composites for advanced applications are also highlighted.

Dynamic behavior of smart material embedded wind turbine blade under actuated condition

  • Mani, Yuvaraja;Veeraragu, Jagadeesh;Sangameshwar, S.;Rangaswamy, Rudramoorthy
    • Wind and Structures
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    • v.30 no.2
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    • pp.211-217
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    • 2020
  • Vibrations of a wind turbine blade have a negative impact on its performance and result in failure of the blade, therefore an approach to effectively control vibration in turbine blades are sought by wind industry. The small domestic horizontal axis wind turbine blades induce flap wise (out-of-plane) vibration, due to varying wind speeds. These flap wise vibrations are transferred to the structure, which even causes catastrophic failure of the system. Shape memory alloys which possess physical property of variable stiffness across different phases are embedded into the composite blades for active vibration control. Previously Shape memory alloys have been used as actuators to change their angles and orientations in fighter jet blades but not used for active vibration control for wind turbine blades. In this work a GFRP blade embedded with Shape Memory Alloy (SMA) and tested for its vibrational and material damping characteristics, under martensitic and austenite conditions. The embedment portrays 47% reduction in displacement of blade, with respect to the conventional blade. An analytical model for the actuated smart blade is also proposed, which validates the harmonic response of the smart blade.

Optical & Mechanical Characteristics of Lining Papers by the Artificial Heat Ageing Treatment (열처리 인공촉진열화가 배접지의 광학적 및 기계적 특성에 미치는 영향)

  • Jeong, Seon-Hwa;Choi, Kyoung-Hwa;Park, Ji-Hee;Kang, Young-Seok;Yoon, Kyoung-Dong
    • 보존과학연구
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    • s.30
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    • pp.93-102
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    • 2009
  • This study was carried out to investigate the effect of artificial accelerated ageing treatment on the permanence of lining papers produced from Korea and Japan. As time gone by, organic cultural properties are affected by chemical and physical deterioration because of various factors including the conditions of preservation environment and their material properties. In the public historical storage or owned as private collections, are vulnerable to sever amages caused by poor preservation environment as well as by other natural factors. In this study, the deterioration behaviors of lining paper in optical & mechanical properties were discussed. Overall, lining papers produced from Korea showed lower reduction in mechanical strength properties compared to the lining papers produced from Japan.

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Effects of Optical Brightening Agents on Aging Characteristics of Paper (형광증백제가 종이의 열화 특성에 미치는 영향)

  • Choi, Kyoung-Hwa;Lee, Jae-Hun;Cho, Byoung-Uk
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.46 no.6
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    • pp.87-93
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    • 2014
  • Optical brightening agents (OBA) is generally used to improve the optical property of printing paper in the paper industry. However, effects of OBA addition on paper preservability has been not fully understood yet. Therefore, this study was aimed to investigate effects of a OBA on the aging characteristics of paper. The OBA treatment of three different types was performed by dipping a filter paper into each a OBA solutions of different concentrations. The filter papers applied with a OBA were artificially aged at 80oC and 65% RH, and their optical and mechanical properties were evaluated. It was found that application of OBAs influenced the aging characteristics of paper. Especially, after aging, the optical and mechanical properties of the filter paper treated with the tetra-type OBA were more significantly decreased than those of the non-treated filter paper. The more the concentration of the tetra-type OBA increased, the more decreasing rate of optical and mechanical properties of the filter paper. While, in case of di-type OBA and hexa-type OBA, paper optical and mechanical properties were slightly decreased or not changed with a OBA treatment.

Design of comprehensive mechanical properties by machine learning and high-throughput optimization algorithm in RAFM steels

  • Wang, Chenchong;Shen, Chunguang;Huo, Xiaojie;Zhang, Chi;Xu, Wei
    • Nuclear Engineering and Technology
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    • v.52 no.5
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    • pp.1008-1012
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    • 2020
  • In order to make reasonable design for the improvement of comprehensive mechanical properties of RAFM steels, the design system with both machine learning and high-throughput optimization algorithm was established. As the basis of the design system, a dataset of RAFM steels was compiled from previous literatures. Then, feature engineering guided random forests regressors were trained by the dataset and NSGA II algorithm were used for the selection of the optimal solutions from the large-scale solution set with nine composition features and two treatment processing features. The selected optimal solutions by this design system showed prospective mechanical properties, which was also consistent with the physical metallurgy theory. This efficiency design mode could give the enlightenment for the design of other metal structural materials with the requirement of multi-properties.