• Title/Summary/Keyword: Fracture behavior

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A Study on Fracture Behavior and Impact Stability of Sintered Rare-earth Permanent Magnets

  • Li, Wei;Li, Anhua;Wang, Huijie;Dong, Shengzhi;Guo, Yongquan
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.790-791
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    • 2006
  • The fracture behavior and mechanical characteristics of sintered rare-earth magnets were investigated. It shows that the fracture behavior and bending strength of the magnets obviously exhibit anisotropy. Sm-Co magnets tend to cleavage fracture in the close-packed (0001) plane or in the ($10\bar{1}1$) plane. The fracture mechanism of $Nd_2Fe_{14}B$ magnet mainly appears to be intergranular fracture. The anisotropy of fracture behavior and mechanical strength of sintered rare-earth magnets is caused mainly by the strong crystal-structure anisotropy and the grain alignment texture. The effects of Nd content, and Pr, Dy substitution on the impact stability of $Nd_2Fe_{14}B$ magnets were also reported.

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Effect of Loading Rate on the Fracture Behavior of Nuclear Piping Materials Under Cyclic Loading Conditions

  • Kim, Jin Weon;Choi, Myung Rak;Kim, Yun Jae
    • Nuclear Engineering and Technology
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    • v.48 no.6
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    • pp.1376-1386
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    • 2016
  • This study investigated the loading rate effect on the fracture resistance under cyclic loading conditions to understand clearly the fracture behavior of piping materials under seismic conditions. J-R fracture toughness tests were conducted under monotonic and cyclic loading conditions at various displacement rates at room temperature and the operating temperature of nuclear power plants (i.e., $316^{\circ}C$). SA508 Gr.1a low-alloy steel and SA312 TP316 stainless steel piping materials were used for the tests. The fracture resistance under a reversible cyclic load was considerably lower than that under monotonic load regardless of test temperature, material, and loading rate. Under both cyclic and monotonic loading conditions, the fracture behavior of SA312 TP316 stainless steel was independent of the loading rate at both room temperature and $316^{\circ}C$. For SA508 Gr.1a lowalloy steel, the loading rate effect on the fracture behavior was appreciable at $316^{\circ}C$ under cyclic and monotonic loading conditions. However, the loading rate effect diminished when the cyclic load ratio of the load (R) was -1. Thus, it was recognized that the fracture behavior of piping materials, including seismic loading characteristics, can be evaluated when tested under a cyclic load of R = -1 at a quasistatic loading rate.

Flexural Fracture Behavior of Reinforced Concrete Beam Based on Fracture Mechanics Approach (파괴역학에 근거한 철근콘크리트 보의 휨 파괴거동)

  • 어석홍;최덕진;홍기호;김희성
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.10a
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    • pp.149-154
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    • 2002
  • An analytical fracture mechanics approach was used to investigate the fracture behavior of reinforced concrete beams. By use of this approach based on fracture mechanics concepts, the crack width and length as well as the strength and cracking stability of reinforced concrete beams were investigated. The results obtained from the analytical studies were also discussed in terms of the minimum reinforcement ratio and crack width specified in design code provisions. The analytical approach based on fracture mechanics concepts are very useful to predict the fracture behavior of reinforced concrete beams.

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The Effect of residual stress for fracture behavior in the laser weldment (레이저용접부의 파괴에 미치는 잔류응력의 영향)

  • Jo, Seong-Gyu;Yang, Yeong-Su
    • Proceedings of the Korean Society of Laser Processing Conference
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    • 2006.06a
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    • pp.3-8
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    • 2006
  • The integrity of laser welded structures is decided with fracture strength and fatigue strength. This study presents fracture behavior considering residual stress in the laser welding. Experiments are conducted and analyses are performed to explore the influence of residual stress on fracture behavior of bead-on laser welded compact specimen. Fracture experiments are performed using ASTM 1820. The performed analyses included thermo-elasto-plastic analyses for residual stress and subsequent J-integral calculation. A modified J integral is calculated in the presence of residual stresses. The J-integral is path-independent for combination of residual stress field and stress due to mechanical loading. The results indicates that the tensile residual stress near crack front bring the low fracture load while the compressive residual stress bring the high fracture load compared to no residual stress specimen. These results quantitatively understand the influence of residual stress on fracture behavior.

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The Effect of residual stress on fracture behavior in the laser weldment (레이저용접부의 파괴에 미치는 잔류응력의 영향)

  • Cho, Sung-Kyu;Yang, Young-Soo;Noh, Young-Jin
    • Laser Solutions
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    • v.11 no.2
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    • pp.1-7
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    • 2008
  • The integrity of laser welded structures is decided in fracture strength and fatigue strength. This study made an effort to understand the fracture behavior considering residual stress. Experiments are conducted and analyses are performed to explore the influence of residual stress on fracture behavior of bead-on laser welded compact specimen. Fracture experiments are performed using ASTM 1820. The performed analyses included thermo-elasto-plastic analyses for residual stress and subsequent J-integral calculation. A modified J integral is calculated in the presence of residual stresses. The J-integral is path-independent for combination of residual stress field and stress due to mechanical loading. The results indicates that the tensile residual stress near crack front bring the low fracture load while the compressive residual stress bring the high fracture load compared to no residual stress specimen. These results quantitatively understand the influence of residual stress on fracture behavior.

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The microstructure and mechanical performance of high strength alloy steel X2M

  • Manigandan, K.;Srivatsan, T.S.;Freborg, A.M.;Quick, T.;Sastry, S.
    • Advances in materials Research
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    • v.3 no.1
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    • pp.283-295
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    • 2014
  • In this paper, the microstructure, hardness, tensile deformation and fracture behavior of high strength alloy steel X2M is presented anddiscussed. The influence of both composition and processing on microstructure of the as-provided material and resultant influence of microstructure, as a function of orientation, on hardness, tensile properties and final fracture behavior is highlighted. The macroscopic mode and intrinsic microscopic features that result from fracture of the steel specimens machined from the two orientations, longitudinal and transverse is discussed. The intrinsic microscopic mechanisms governing quasi-static deformation and final fracture behavior of this high strength steel are outlined in light of the effects oftest specimen orientation, intrinsic microstructural effects and nature of loading.

Analysis of Compressive Fracture Behavior of Filled FRP Composite Box Module (충전형 FRP 합성박스 모듈의 압축파괴 거동 분석)

  • Kim, Ho-Sun;Jang, Hwa-Sup;Lee, Ho-Hyun;Yun, Kuk-Hyun
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.25 no.1
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    • pp.1-8
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    • 2012
  • This study is a basic experimental research to apply FRP (Fiber Reinforced Polymer) box members to slabs and girders among various architectural structures, which receive bending stress. We prepared prefabricated FRP member and connected it to an FRP box member as a large cross section before we conducted an experiment in diverse conditions to analyze characteristics of compressive fracture behavior. In this study, we carried out a compressive fracture behavior test according to fillers on the upper part of the FRP box member, loading methods, and connective types and thereby performed a finite element analysis. The comparison of analysis results with test results revealed that rigidity was found to be slightly low, while stress was concentrated on the fracture point of the sample.

A Study on Fracture Behavior of Scaled Model for Ceramic Dome Port Cover (세라믹 돔포트 커버 상사모델의 파괴거동에 관한 연구)

  • Hwang, Kwon-Tae;Kim, Jae-Hoon;Lee, Young-Shin;Park, Jong-Ho;Song, Kee-Hyuck;Yoon, Soo-Jin
    • Journal of the Korean Society of Propulsion Engineers
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    • v.13 no.4
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    • pp.55-62
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    • 2009
  • Fracture behavior of ceramic dome port cover on air breathing engine using liquid and solid fuel propulsion system was carried out in this study. Fracture characteristics was tested and estimated using scaled model of ceramic dome port cover by Shock tube. Fracture behavior was obtained by the fracture pressure from pressure sensor and observed the scattering phenomena of fracture specimen using high speed camera. Results obtained from this study can be used in the base data of dome port cover design for an air breathing engine.

Evaluation of Deformation and Strength of Wall Thinne Pipes by Finite Element Analysis (감육배관의 유한요소해석에 의한 변형 및 강도 평가)

  • NAM KI-WOO;AHN SEOK-HWAN;LEE SOO-SIG;KIM JIN-WOOK;YOON JA-MUN
    • Journal of Ocean Engineering and Technology
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    • v.19 no.5 s.66
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    • pp.65-70
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    • 2005
  • Fracture behavior and pipe strength are very important to the integrity of energy plants, ocean structures, and so forth. The pipes of energy plants and ocean structures are subject to local wall thinning, resulting from severe erosion-corrosion damage. Recently, the effects of local wall thinning on fracture strength and fracture behavior of piping systems have been the focus of many studies. In this paper, the elasto-plastic analysis is performed by FE code ANSYS on straight pipes with wall thinning. We evaluated the failure mode, fracture strength and fracture behavior, using FE analysis. Also, the effect of the axial strain on deformations and failure modes was estimated by FE analysis.

A Study on the Influence of Fiber Orientation on the Mode I Interlaminar Fracture Behavior of Carbon/Epoxy Composite materials (탄소섬유/에폭시 복합재료의 Mode I 층간파괴거동에 미치는 섬유배향각의 영향에 관한 연구)

  • 이택순;최영근
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.2
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    • pp.391-401
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    • 1995
  • Several tests of the Double Cantilever Beam(DCB) were carried out for influence of the fiber orientation on the Mode I of the interlaminar fracture behavior in the Carbon/Epoxy composites. The interlaminar fracture toughness of Mode I was estimated based on the energy release rate of Mode I, $G_{I}$. The fracture toughness at crack initiation, $G_{IC}$, increases from type A to type E. The fracture toughness, $G_{IR}$ , is almost constant macroscopically for type A and type E when crack propagates. $G_{IR}$ for types B, C, D increases rapidly at the beginning of the crack growth then it decreases gradually. The fracture surface observation by SEM was also obtained the same results. Consequently the influence of the fiber orientation on the Mode I Interlaminar fracture behavior was made clear.ear.