• Title/Summary/Keyword: 동적 응력-변형률 곡선

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Dynamic tensile behavior of PMMA (PMMA의 동적 인장 거동)

  • Lee, Ouk-Sub;Kim, Myun-Soo;Hwang, Si-Won
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.395-400
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    • 2001
  • The Split Hopkinson Pressure Bar(SHPB) technique, a special experimental apparatus, has been used to obtain the material behavior under high strain rate loading condition. In this paper, dynamic deformation behaviors of the PMMA under high strain rate tensile loading are determined using SHPB technique.

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Determination of Dynamic Tensile Behavior of Al5052-H32 using SHPB Technique (SHPB 테크닉을 이용한 Al5052-H32의 동적 인장 거동 규명)

  • 이억섭;김면수;백준호
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.10a
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    • pp.790-794
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    • 1997
  • Mechanical properties of the materials used for transportations and industrial machinery under high strain rate loading conditions such as seismic loading are required to provide appropriate safety assessment to those mechanical structures. The Split Hopkinson Pressure Bar(SHPB) technique with a special experimental behavior under high strain rate loading condition In this paper, dynamic deformation behaviors of A15052-H32 under high strain rate tensile loading are determined using the SHPB technique.

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Study on the Dynamic Stress-Strain Behavior of Solid Propellant Using Low-Velocity Impact Test (저속충격시험을 이용한 고체추진제의 동적 응력-변형률 특성 연구)

  • Hwang, Jae-Min;Go, Eun-Su;Jo, Hyun-Jun;Kim, In-Gul;Kim, Jae-Hoon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.49 no.10
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    • pp.813-820
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    • 2021
  • In this study, a low-velocity impact test was performed to obtain the dynamic properties of solid propellants. The dynamic behavior of the solid propellant was examined by measuring the force and displacement of the impactor during the low-velocity impact test. The bending displacement was calculated by compensating for the local displacement caused by the low-velocity impact test in the form of three point bending and the shear displacement caused by using a short and thick solid propellant specimen. Stress and strain were calculated using compensated displacements and measured force, and dynamic properties of solid propellants were obtained from the stress-strain curve and compared with static bending test. The dynamic properties of solid propellant under the low-velocity impact loading at various operating temperature conditions such as room temperature(20 ℃), high temperature(63 ℃), and low temperature(-32 ℃) were compared and investigated.

High Temperature Deformation Behavior of Microalloyed Hot Forging Steels (열간 단조용 비조질강의 고온 변형 거동에 관한 연구)

  • Wi, Gyeom-Bok;Lee, Gyeong-Seop
    • Korean Journal of Materials Research
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    • v.2 no.5
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    • pp.343-352
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    • 1992
  • The high temperature deformation behavior of microalloyed hot forging steels has been examined as a function of the temperature, the strain rate, and the alloying element by using high temperature compression test. The high temperature deformation mechanism, which was obtained by analyzing the flow stress-strain curve and microstructure, could be considered to dynamic recrystallization. The peak stress of Nb-V-Mo steel was more increased and the dynamic recrystallization of Nb-V-Mo steel was faster than those of Nb-V steel. The peak stress of 1.2Mn-0.09Nb steel was more increased and the dynamic recrystallization of 1.2Mn-0.09Nb was delayed a little bit than those of 1.0Mn-0.05Nb. The peak stress of C-Nb-V steel was more increased and the dynamic recrystallization of C-Nb-V steel was delayed than those of C-steel. The constitutive equation of high temperature deformation had a power law type. The grain size of dynamic recrystallization was refined as the Zener-Hollomon parameter was increased. The relation of the dynamic recrystallization grain size and Zener-Hollomon parameter could be quantified to power law.

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Material model optimization for dynamic recrystallization of Mg alloy under elevated forming temperature (마그네슘 합금의 온간 동적재결정 구성방정식 최적화)

  • Cho, Yooney;Yoon, Jonghun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.6
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    • pp.263-268
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    • 2017
  • A hot forming process is required for Mg alloys to enhance the formability and plastic workability due to the insufficient formability at room temperature. Mg alloy undergoes dynamic recrystallization (DRX) during the hot working process, which is a restoration or softening mechanism that reduces the dislocation density and releases the accumulated energy to facilitate plastic deformation. The flow stress curve shows three stages of complicated strain hardening and softening phenomena. As the strain increases, the stress also increases due to work hardening, and it abruptly decreases work softening by dynamic recrystallization. It then maintains a steady-state region due to the equilibrium between the work hardening and softening. In this paper, an efficient optimization process is proposed for the material model of the dynamic recrystallization to improve the accuracy of the flow curve. A total of 18 variables of the constitutive equation of AZ80 alloy were systematically optimized at an elevated forming temperature($300^{\circ}C$) with various strain rates(0.001, 0.1, 1, 10/sec). The proposed method was validated by applying it to the constitutive equation of AZ61 alloy.

A Modified Parallel Iwan Model for Cyclic Hardening Behavior of Sand(I) : Model Development (수정 IWAN 모델을 이용한 사질토의 반복경화거동에 대한 연구(I): 모델 개발)

  • 이진선;김동수
    • Journal of the Earthquake Engineering Society of Korea
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    • v.7 no.5
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    • pp.47-56
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    • 2003
  • In this paper, the cyclic soil behavior model. which can accommodate the cyclic hardening, was developed by modifying the original parallel IWAN model. In order to consider the irrecoverable plastic strain of soil. the cyclic threshold strain, above which the backbone curve deviates from the original curve, was defined and the accumulated strain was determined by summation of the strains above the cyclic threshold in the stress-strain curve with applying Masing rule on unloading and reloading curves. The isotropic hardening elements are attached to the original parallel IWAN model and the slip stresses in the isotropic hardening elements are shown to increase according to the hardening functions. The hardening functions have a single parameter to account for the cyclic hardening and are defined by the symmetric limit cyclic loading test in forms of accumulated shear strain. The model development procedures are included in this paper and the verifications of developed model are discussed in the companion paper.

Determination of Deformation Behavior of the Al6060-T6 under high Strain Rate Tensile Loading Using SHPB Technique (SHPB 기법을 이용한 A16061-T6의 고속 인장 변형거동 규명)

  • Lee, Eok-Seop;Kim, Gwan-Hui;Hwang, Si-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.12
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    • pp.3033-3039
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    • 2000
  • Mechanical properties of the materials used for transportations and industrial machinery under high stain rate loading conditions have been required to provide appropriate safety assessment to these mechanical structures. The Split Hopkinson Pressure Bar(SHPB) technique with a special experimental apparatus can be used to obtain the material properties under high strain rate loading condition. There have been many studies on the material behavior under high strain rate compressive loading compared to those under tensile loading. In this paper, mechanical properties of the aluminum alloy, Al6061-T6, under high strain rate tensile loading were determined using SHPB technique.

Dynamic deformation behavior of aluminum alloys under high strain rate compressive/tensile loading (상용 알루미늄 합금의 고속 인장/압축 변형거동 규명)

  • Lee, O.S.;Kim, G.H.;Kim, M.S.;Hwang, S.W.
    • Proceedings of the KSME Conference
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    • 2000.11a
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    • pp.268-273
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    • 2000
  • Mechanical properties of the materials used for transportations and industrial machinery under high strain rate loading conditions are required to provide appropriate safety assessment to these mechanical structures. The Split Hopkinson Pressure Bar(SHPB) technique, a special experimental apparatus, can be used to obtain the material behavior under high strain rate loading condition. In this paper, dynamic deformation behaviors of the aluminum alloys, Al2024-T4, Al6061-T6 and Al7075-T6, under high strain rate compressive and tensile loading are determined using SHPB technique.

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SHPB Tests for Rock Dynamic Behavior by Shock Loading (충격하중에 의한 암석의 동적거동 측정시험장치)

  • Park, Chul-Whan;Park, Eui-Seob
    • Tunnel and Underground Space
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    • v.20 no.5
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    • pp.318-324
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    • 2010
  • Dynamic properties of materials by shock loads such as rock blasting and earthquake are recently attracted in the design of aboveground and underground structures. The advance of measuring devices enables to obtain the whole histories of stress and strain in rock specimen of which the failure is completed in several hundred microseconds. The SHPB has been a popular and promising technique to study the dynamic behavior of rock. And the dynamic compressive, tensile and other test with this experiment system are planned to be Suggested Methods of ISRM. This technical paper is to introduced one study article which focuses the design of 3S (special shaped striker) to produce the half-sine wave to eliminate the problems of the rectangular wave. This article is also describing the advantage of half-sine incident wave and size effect of rock dynamic strength.

A New Higher-Order Hybrid-Mixed Element for Curved Beam Vibrations (곡선보의 자유진동해석을 위한 고차 혼합요소)

  • Kim Jin-Gon;Park Yong-Kuk
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.19 no.2 s.72
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    • pp.151-160
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    • 2006
  • In this study, we propose a new efficient 2-noded hybrid-mixed element for curved beam vibrationshaving a uniform and non-uniform cross section. The present element considering transverse shear strain is based on Hellinger-Reissner variational principle and introduces additional nodeless degrees for displacement field interpolation in order to enhance the numerical performance. The stress parameters are eliminated by the stationary condition and then the nodeless degrees are condensed out by the Guyan reduction. In the performance evaluation process of the present field-consistent higher-order element, we carefully examine the effects of field consistency and the role of higher-order interpolation functions on the hybrid-mixed formulation. Several benchmark tests confirm e superior behavior of the present hybrid-mixed element for curved beam vibrations.