• 제목/요약/키워드: D. Mechanical properties

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Mechanical Properties and Microstructure Examinations on Austempered Ductile Irons (Austempered Ductile Iron(A.D.I.)의 기계적 성질과 현미경 조직검사)

  • Lee, Seung Seok
    • Journal of the Korean Society for Heat Treatment
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    • v.3 no.1
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    • pp.25-33
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    • 1990
  • Recently developed austempered ductile irons(A.D.I.) have good mechanical properties. However it is still needed to examine the relationships between microstructures related to banitic reaction and the mechanical properties. From the mechanical tests such as impact test, hardness test, tensile test, and the microstructure observations, we concluded that the good mechanical properties of A.D.I. came from the fine banitic ferrite structure formed during the first stage of the austempering reaction.

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Effect of Post-processing on Mechanical Properties of 3D Printed Carbon Chopped Fiber Reinforced Composites (3D 프린팅 된 탄소 단섬유강화 복합재료의 후처리 효과가 재료의 기계적 성능에 미치는 영향)

  • Jia-le, Che;Seung-Hwan, Chang
    • Composites Research
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    • v.35 no.6
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    • pp.463-468
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    • 2022
  • The high porosity of the infill pattern of carbon chopped fiber-reinforced Nylon composite structures fabricated by the fused filament fabrication (FFF) type 3D printers determines the mechanical performance of the printed structures. This study experimentally evaluated the mechanical performance of Onyx composite specimens fabricated with a rectangular infill structure under the hot-pressing condition to improve the mechanical properties by reducing the porosity of the infill pattern of the printed structure, and evaluated the best mechanical performance. The hot-pressing conditions (145℃, 4 MPa, 12 min) that induce the most appropriate mechanical properties were found. As a result of microscopic observation, it was confirmed that the infill porosity of the composite specimens subjected to post hot-pressing treatment was effectively reduced. In order to confirm the mechanical performance of the post-treated specimen, a tensile test and a three-point bending test were performed with a control specimen without post-treatment and a specimen printed with the same density and dimensions after post-treatment to evaluate the mechanical properties. As a result of comparison, it was confirmed that the mechanical properties were effectively improved when the post-treatment of hot-pressing was performed.

Study of the Mechanical Properties and Orthotropy of ABS Materials Fabricated by FDM Printing (FDM 프린팅으로 제작된 ABS 소재의 기계적 특성 및 직교이방성 연구)

  • Yoon, Juil
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.17 no.5
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    • pp.143-148
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    • 2018
  • 3D printing has been expanding beyond the bio/nano field to the automobile and aviation industries. 3D-printing technology has to overcome real problems to have economic value compared to its unlimited usability. Typically, the difference in mechanical strength along the lamination direction requires sufficient research to ensure reliability. In this paper, we study the anisotropic properties of ABS based on the stacking method of FDM 3D printing. Specifically, the mechanical properties of ABS material are determined through a tensile test and 3-point bending test, and the in-plane orthotropic properties are ascertained.

Study of the mechanical properties and effects of particles for oxide dispersion strengthened Zircaloy-4 via a 3D representative volume element model

  • Kim, Dong-Hyun;Hong, Jong-Dae;Kim, Hyochan;Kim, Jaeyong;Kim, Hak-Sung
    • Nuclear Engineering and Technology
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    • v.54 no.5
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    • pp.1549-1559
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    • 2022
  • As an accident tolerant fuel (ATF) concept, oxide dispersion strengthened Zircaloy-4 (ODS Zry-4) cladding has been developed to enhance the mechanical properties of cladding using laser processing technology. In this study, a simulation technique was established to investigate the mechanical properties and effects of Y2O3 particles for the ODS Zry-4. A 3D representative volume element (RVE) model was developed considering the parameters of the size, shape, distribution and volume fraction (VF) of the Y2O3 particles. From the 3D RVE model, the Young's modulus, coefficient of thermal expansion (CTE) and creep strain rate of the ODS Zry-4 were effectively calculated. It was observed that the VF of Y2O3 particles had a significant effect on the aforementioned mechanical properties. In addition, the predicted properties of ODS Zry-4 were applied to a simulation model to investigate cladding deformation under a transient condition. The ODS Zry-4 cladding showed better performance, such as a delay in large deformation compared to Zry-4 cladding, which was also found experimentally. Accordingly, it is expected that the simulation approach developed here can be efficiently employed to predict more properties and to provide useful information with which to improve ODS Zry-4.

Improvement of the Representative Volume Element Method for 3-D Scaffold Simulation

  • Cheng Lv-Sha;Kang Hyun-Wook;Cho Dong-Woo
    • Journal of Mechanical Science and Technology
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    • v.20 no.10
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    • pp.1722-1729
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    • 2006
  • Predicting the mechanical properties of the 3-D scaffold using finite element method (FEM) simulation is important to the practical application of tissue engineering. However, the porous structure of the scaffold complicates computer simulations, and calculating scaffold models at the pore level is time-consuming. In some cases, the demands of the procedure are too high for a computer to run the standard code. To address this problem, the representative volume element (RVE) theory was introduced, but studies on RVE modeling applied to the 3-D scaffold model have not been focused. In this paper, we propose an improved FEM-based RVE modeling strategy to better predict the mechanical properties of the scaffold prior to fabrication. To improve the precision of RVE modeling, we evaluated various RVE models of newly designed 3-D scaffolds using FEM simulation. The scaffolds were then constructed using microstereolithography technology, and their mechanical properties were measured for comparison.

Study on the Evaluation of D.P. and Handle for Vapor Phase Finished Fabrics (V.P.가공 직물의 D.P.성과 Handle 평가에 관한 연구)

  • 최근영;백천의
    • Journal of the Korean Society of Clothing and Textiles
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    • v.20 no.5
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    • pp.792-800
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    • 1996
  • The shape retention finishing provides a fabric for easiness of no-ironing after laundering. In spite of the obvious importance of the new finishing treatment, few systematic studies have been performed on the handle of the fabrics finished by the durable press process. The purpose of this research is to investigate the relationships among the mechanical properties, durable press conditions, primary hand values and the total hand value of the fabrics finished by shape retention process. In this experiment, durable press grade of unfinished fabrics decreased below 2.5, but those of finished fabrics maintained above 4, but the mechanical properties of finished fabrics did not change significantly after laundering. In finished fabrics, D.P. value were correlated with mechanical properties, but had little effects with H.V. and T.H.V. Since the evaluation of the effect of durable press process was done with the naked eyes and standard sample, we could not know exactly change o( mechanical properties, but trace the change of mechanical properties which gave influences on the durable press effects by using KES-FB System.

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Dynamic Magneto-mechanical Behavior of Magnetization-graded Ferromagnetic Materials

  • Chen, Lei;Wang, Yao
    • Journal of Magnetics
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    • v.19 no.3
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    • pp.215-220
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    • 2014
  • This study investigates the dynamic magneto-mechanical behavior of magnetization-graded ferromagnetic materials Terfenol-D/FeCuNbSiB (MF). We measure the dynamic magneto-mechanical properties as a function of the DC bias magnetic field ($H_{dc}$). Our experimental results show that these dynamic magneto-mechanical properties are strongly dependent on the DC bias magnetic field. Furthermore, the dynamic strain coefficient, electromechanical resonance frequency, Young's moduli, and mechanical quality factor of Terfenol-D/FeCuNbSiB are greater than those of Terfenol-D under a lower DC bias magnetic field. The dynamic strain coefficient increases by a factor of between one and three, under the same DC bias magnetic field. In particular, the dynamic strain coefficient of Terfenol-D/FeCuNbSiB at zero bias achieves 48.6 nm/A, which is about 3.05 times larger than that of Terfenol-D. These good performances indicate that magnetization-graded ferromagnetic materials show promise for application in magnetic sensors.

3D Printable Composite Materials: A Review and Prospective (3D 프린터용 복합재료 연구 동향)

  • Oh, Eunyoung;Lee, Jinwoo;Suhr, Jonghwan
    • Composites Research
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    • v.31 no.5
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    • pp.192-201
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    • 2018
  • The use of 3D printing for rapid tooling and manufacturing has promised to produce components with complex geometries according to computer designs and it is emerging as the next generation key of manufacturing. Due to the intrinsically limited mechanical/electrical properties and functionalities of printed pure polymer parts, there is a critical need to develop 3D printable polymer composites with high performance. This article gives a review on 3D printing techniques of polymer composite materials and the properties and performance of 3D printed composite parts as well as their potential applications in the various fields.

Surface Modified Glass-Fiber Effect on the Mechanical Properties of Glass-Fiber Reinforced Polypropylene Composites

  • Park, Sanghoo;Kim, Su-Jong;Shin, Eun Seob;Lee, Seung Jun;Kang, Beom Mo;Park, Kyu-Hwan;Hong, Seheum;Hwang, Seok-Ho
    • Elastomers and Composites
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    • v.54 no.3
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    • pp.182-187
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    • 2019
  • To improve the mechanical properties of glass-fiber-reinforced polypropylene (PP) composites through interfacial adhesion control between the PP matrix and glass fiber, the surface of the glass fiber was modified with PP-graft-maleic anhydride (MAPP). Surface modification of the glass fiber was carried out through the well-known hydrolysis-condensation reaction using 3-aminopropyltriethoxy silane, and then subsequently treated with MAPP to produce the desired MAPP-anchored glass fiber (MAPP-a-GF). The glass-fiber-reinforced PP composites were prepared by typical melt-mixing technique. The effect of chemical modification of the glass fiber surface on the mechanical properties of composites was investigated. The resulting mechanical and morphological properties showed improved interfacial adhesion between the MAPP-a-GF and PP matrix in the composites.

Mechanical Properties and Morphology of Polyamide/Polypropylene Blends

  • Kim, Su Young;Ha, Jin Uk;Shin, Donghyeok;Jung, Wooseok;Lee, Pyoung-Chan
    • Elastomers and Composites
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    • v.55 no.1
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    • pp.1-5
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    • 2020
  • This study examined the effects of the addition of maleic anhydride-grafted polypropylene (PP-g-MA) and polyolefin elastomer (POE) on polyamide 66 (PA66) and polypropylene (PP) blends. The blends of PA66/PP with PP-g-MA and POE were prepared using a twin screw extruder. Mechanical testing results revealed that the tensile, flexural, and izod impact strengths of the blends were maximized at a PP-g-MA content of 2 phr. The increased mechanical strength of the blends with PP-g-MA was attributed to the compatibilizing effect of the PA66 and PP blends. In addition, as the POE content increased, the impact strength of the blends increased. However, at a high POE content, the tensile and flexural strengths decreased, seemingly because of the lower mechanical properties of POE.