• Title, Summary, Keyword: Permanent Softening

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Springback prediction of friction stir welded DP590 steel sheets considering permanent softening behavior (영구 연화 거동을 고려한 마찰교반용접(FSW) 된 DP강 판재의 탄성 복원 예측)

  • Park, T.;Lee, W.;Chung, K.H.;Kim, J.H.;Kim, D.;Kim, Chong-Min;Okamoto, Kazutaka;Wagoner, R.H.;Chung, K.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.304-307
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    • 2008
  • In order to evaluate the effect of permanent softening behavior on springback prediction, 2D-draw bending simulations were compared with experiments for friction stir welded DP590 steel sheets. To account fur the nonlinear hardening behavior, the combined isotropic-kinematic hardening law was utilized with and without considering the permanent softening behavior during reverse loading. Also, the non-quadratic orthotropic yield function, Yld2000-2d, was used to describe the anisotropic initial-yielding behavior of the base sheet while anisotropic properties of the weld zone were ignored for simplicity.

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Springback Prediction of Friction Stir Welded DP590 Steel Sheet Considering Permanent Softening Behavior (영구연화거동을 고려한 마찰교반용접(FSW)된 DP590 강판의 탄성복원 예측)

  • Kim, J.;Lee, W.;Chung, K.H.;Park, T.;Kim, D.G.;Kim, Chong-Min;Kim, D.
    • Transactions of Materials Processing
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    • v.18 no.4
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    • pp.329-335
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    • 2009
  • In order to better predict the springback for friction stir welded DP590 steel sheet, the combined isotropic-kinematic hardening was formulated with considering the permanent softening behavior during reverse loading. As for yield function, the non-quadratic anisotropic yield function, Yld2000-2d, was used under plane stress condition. For the verification purposes, comparisons of simulation and experiments were performed here for the unconstrained cylindrical bending, the 2-D draw bending tests. For two applications, simulations showed good agreements with experiments.

Permanent Deformation Properties of Asphalt Binder Modified by Pyrolysis Carbon Black of Waste Tires (열분해 카본블랙을 이용한 아스팔트 바인더의 소성변형 특성)

  • Lee, Dong-Hang;Kim, Jung-Ku;Lee, Kwan-Ho
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.8
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    • pp.4028-4032
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    • 2013
  • Recycling method for pyrolyzed carbon black from pyrolysis process of waste tires is needed. Carbon black from pyrolysis of waste tires was used to modify and improve the permanent deformation properties of asphalt binder. 0%, 5%, 10%, 15% and 20% of pyrolyzed carbon black was mixed. Couple of laboratory tests, such as softening point, flash point test, rotational viscometer test and dynamic shear rheometer test, were carried out. The use of pyrolyzed carbon black incresed the softening point, rotational viscosity at 135oC, and resistance of permanent deformation.

Computational modelling for description of rubber-like materials with permanent deformation under cyclic loading

  • Guo, Z.Q.;Sluys, L.J.
    • Interaction and multiscale mechanics
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    • v.1 no.3
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    • pp.317-328
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    • 2008
  • When carbon-filled rubber specimens are subjected to cyclic loading, they do not return to their initial state after loading and subsequent unloading, but exhibit a residual strain or permanent deformation. We propose a specific form of the pseudo-elastic energy function to represent cyclic loading for incompressible, isotropic materials with stress softening and residual strain. The essence of the pseudo-elasticity theory is that material behaviour in the primary loading path is described by a common elastic strain energy function, and in unloading, reloading or secondary unloading paths by a different strain energy function. The switch between strain energy functions is controlled by the incorporation of a damage variable into the strain energy function. An extra term is added to describe the permanent deformation. The finite element implementation of the proposed model is presented in this paper. All parameters in the proposed model and elastic law can be easily estimated based on experimental data. The numerical analyses show that the results are in good agreement with experimental data.

Synthesis of Silicone Softner for Permanent Press Finish and Its Characterization (Permanent Press 가공용 실리콘 유연제의 합성과 그의 특성화)

  • Park, Chang-Hwan;Kim, Seung-Jin;Kim, Young-Geun;Park, Hong-Soo
    • Journal of the Korean Applied Science and Technology
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    • v.12 no.1
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    • pp.29-34
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    • 1995
  • Silicone softner(SSN-3) for permanent press(PP) finish was prepared by blending beef tallow hardened oil for Improving softness, water, the emulsion, which was synthesized from pentaerythritol monostearate as a softening component and silicone oil KF-96 as a lubricating component. The prepared SSN-3 and the PP finishing resin were applied to PP finishing cotton broad cloth and P/C gingham samples using one bath method. The properties such as crease recovery, tear strength, bending resistance test were tested. The samples treated with SSN-3 and PP finishing resin have improved properties, compared with nontreated samples, those treated only with PP finishing resin, those treated with commercial PP finishing softners and PP finishing resin. Also from the bending resistance test, the two kinds of fabric samples treated with SSN-3 of 3% showed grade 5 and these were good enough in feeling.

Synthesis and Characteristics of Lubricating Softner for PP Finish (PP 가공용 평활유연제의 합성과 특성연구)

  • Seo, Kum-Jong;Kwon, Soon-Yong;Park, Hong-Soo
    • Journal of the Korean Applied Science and Technology
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    • v.15 no.1
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    • pp.1-7
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    • 1998
  • Lubricating softner(SOS-2) for permanent press(PP) finish was prepared by blending water, beef tallow hardened oil for improving softness, and the emulsion which was synthesized from N-hexadecanoyl-N,N'-bis(2-hexadecamidoethyl)amine as a softening component and silicone oil KF-96 as a lubricating component. The prepared SOS-2 and the PP finishing resin were applied to PP finishing cotton broad cloth and P/C gingham samples using one bath method. The properties such as tear strength, crease recovery, bending resistance test were tested. The samples treated with SOS-2 and PP finishing resin have improved properties, compared with nontreated samples, those treated only with PP finishing resin, those treated with commercial PP finishing softners and PP finishing resin.

Treatment of Tooth Discoloration using Microabrasion Technique : Case Report (Microabrasion Techinique을 이용한 치아변색의 치료증례)

  • Park, Hi-Ryoung;Kim, Jong-Soo;Kim, Yong-Kee
    • JOURNAL OF THE KOREAN ACADEMY OF PEDTATRIC DENTISTRY
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    • v.24 no.3
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    • pp.511-517
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    • 1997
  • Tooth discoloration detracts from one's appearance and influences self-image and it is particularly true in children. Therefore, pediatric dentists are required to treat tooth discoloration manifested in children for the normal development of their psycosocial health. Three treatment modalities are currently availabler for the removal of a variety of intrinsic stains from vital teeth. These are enamel microabrasion technique using hydrochloric acid, office bleaching and home bleaching technique with carbamide. Microabrasion technique has several advantages over bleaching in that it is easy to accomplish and does not require multiple office visits or the expensive instruments and the color change seems to be permanent after treatment. The process relies on decalcification, a softening with HCl and then removal of the enamel containing the stain with rubbing. Due to the mechanism of stain removal, this method is indicated for the removal of superficial enamel stains or disc oloration only. We report four successfully treated cases by enamel microabrasion using 15% HCl and pumice. Entire clinical steps are described in detail with some discussions on the outcome.

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Preparation and Physical Properties of Silicone Softner for PP Finish (PP 가공용 실리콘 유연제의 제조와 물성연구)

  • Im, Wan-Bin;Yang, In-Mo;Jung, Choong-Ho;Hahm, Hyun-Sik;Park, Hong-Soo
    • Journal of the Korean Applied Science and Technology
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    • v.19 no.2
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    • pp.117-122
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    • 2002
  • A silicone softner (SS-5), a permanent press (PP) finish, was prepared by blending silicone oil KF-96 (as a lubricating component) and beef tallow hardened oil (as a softening component) which was synthesized from fatty polyamide salts. The prepared SS-5 and the PP finishing resin were applied to PP finishing cotton cloth and P/C gingham sample by one-bath method. The properties such as crease recovery, tear strength, and bending resistance were tested. The samples treated with SS-5 and PP finishing resin showed improved properties when comparing with the untreated ones, with the ones treated only with PP finishing resin, with ones treated with commercial PP finishing softners and PP finishing resin. The grades of fabric samples treated with 3% SS-5 were fifth grade in the bending resistance test.

Thermal Deformation of Glass Backplane during Flash Lamp Crystallization Process of Amorphous Silicon (플래시 램프를 이용한 비정질 실리콘 결정화 공정에서의 유리기판 열변형)

  • Kim, Dong-Hyun;Kim, Byung-Kuk;Kim, Hyoung-June;Chung, Ha-Seung;Park, Seung-Ho
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.36 no.10
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    • pp.1025-1032
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    • 2012
  • The flash lamp annealing (FLA) process has been considered highly promising for manufacturing low-temperature polysilicon on large-scale backplanes. Based on a theoretical estimation, this study clarifies the critical mechanisms of glass backplane deformation during the FLA process. A simulation using a commercial FEM code with viscoelastic models shows that the local region, whose temperature is larger than the glass softening point, undergoes permanent structural shrinkage owing to stress relaxation. For larger backplanes (4th Gen), structural shrinkages and gravitational deflection are critical to deformation in the FLA process, resulting in an "M" shape; in smaller backplanes (0th Gen), the latter is negligible, resulting in a "U" shape.