• Title, Summary, Keyword: Full Specimen

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Small-size Specimen's Effectiveness That is Used to Mortar Layer of Slab (Heavy-weight Floor Impact Sound) (슬래브 상부 몰탈층에 사용된 작은시편의 유효성 검토(중량충격음을 중심으로))

  • Chung, Jin-Yun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.2
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    • pp.184-191
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    • 2009
  • This study examined small-size specimen's effectiveness that is used to evaluate floor impact sound performance. Floor impact sound level of small-size specimen is higher than full-size. This is due to excessive impact power of Bang machine. Impact hammer that has small impact power relatively can solve this problem. But, according to the size of specimen, mode shape and frequency that influence to structural borne sound is changed. Slab mode of full-size specimen was changed to frequency design of resilient materials. But in case of small-size specimen, there is no change of vibration mode by resilient materials change, Vibration mode of small-size specimen is the same. Therefore, it is not proper that use small-size specimen in floor impact sound estimation.

Prediction of Failure Behavior for Nuclear Piping Using Curved Wide-Plate Test (흰 광폭평판 시험을 이용한 원자력 배관의 파괴거동예측)

  • Huh, Nam-Su;Kim, Yun-Jae;Choi, Jae-Boong;Kim, Young-Jin;Lim, Hyuk-Soon;Chung, Dae-Yul
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.4
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    • pp.352-361
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    • 2004
  • One important element of the Leak-Before-Break analysis of nuclear piping is how to determine relevant fracture toughness (or the J-resistance curve) for nonlinear fracture mechanics analysis. The practice to use fracture toughness from a standard C(T) specimen is known to often give conservative estimates of toughness. To improve the accuracy, this paper proposes a new method to determine fracture toughness using a nonstandard testing specimen, curved wide-plate in tension. To show validity of the proposed curved wide-plate test, the J-resistance curve from the full-scale pipe test is compared with that from the curved wide-plate test and that from the C(T) specimen. It is shown that the J-resistance curve form the curved wide-plate tension test is similar to, but that from the C(T) specimen is lower than, the J-resistance curve from the full-scale pipe test. Further validation is performed by investigating crack-tip constraint conditions via detailed 3-D FE analyses, which shows that the crack-tip constraint condition in the curved wide-plate tension specimen is indeed similar to that in the full-scale pipe under bending.

Development of a Piping Integrity Evaluation Simulator Based on the Hardware-in-the-Loop Simulation (하드웨어-인-더-루프 기반의 배관 평가 시뮬레이터의 개발)

  • Kim, Yeong-Jin;Heo, Nam-Su;Cha, Heon-Ju;Choe, Jae-Bung;Pyo, Chang-Ryul
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.7
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    • pp.1031-1038
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    • 2001
  • In order to verify the analytical methods predicting failure behavior of cracked piping, full-scale pipe tests are crucial in nuclear power plant piping. For this reason, series of international test programs have been conducted. However, full-scale pipe tests require expensive testing equipment and long period of testing time. The objective of this paper is to develop a test system which can economically simulate the full-scale pipe test regarding the integrity evaluation. This system provides the failure behavior of cracked pipe by testing a wide-plate specimen. The system provides the failure behavior of cracked pipe by testing a wide-plate specimen. The system was developed for the integrity evaluation of nuclear piping based on the methodology of hardware-in-the-loop (HiL) simulation. Using this simulator, the piping integrity can be evaluated based on the elastic-plastic behavior of full-scale pipe, and the high cost full-scale pipe test may be replaced with this economical system.

Deformation behavior of the Fe-18Cr-14Mn-4Ni-0.9N high nitrogen steel under different strain rate conditions (Fe-18Cr-14Mn-4Ni-0.9N 고질소 내식강의 고온 석출과 변형률 속도에 따른 변형특성 연구)

  • Nam, S.M.;Kim, Y.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.421-424
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    • 2006
  • High nitrogen steels (HNS) exhibit both high strength and ductility during tensile deformation. In the present study the Fe-18Cr-14Mn-4Ni-0.9N high nitrogen steel was heat treated at $1000^{\circ}C$ and $1100^{\circ}C$ to produce $Cr_2N$ precipitates in austenite matrix and full austenite microstructures, respectively. Tensile tests of the heat treated specimens were performed at two different strain rates of 0.05/sec and 0.00005/sec. Each tensile curve of the specimens could be well characterized by the the modified Ludwik equation. Plastic deformation of the steel was adequately represented by the four parameters of the modified Ludwik equation. At 0.05/s strain rate, the specimen with the $Cr_2N$ precipitate exhibited higher strength than the full austenite specimen, while the full austenite specimen showed better mechanical properties at 0.00005/s strain rate. It was found that the $Cr_2N$ precipitates influences deformation behavior of the high nitrogen steel significantly.

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Behavior of CFT Column to H-Beam Full-Scale Connections with External T-Stiffeners (T-스티프너 보강 CFT 기둥 - H형강보 실대형 접합부의 거동)

  • Kim, Young Ju;Kang, Chang Hoon;Shin, Kyung Jae;Oh, Young Suk;Moon, Tae Sup
    • Journal of Korean Society of Steel Construction
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    • v.13 no.6
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    • pp.715-723
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    • 2001
  • This paper represents the behavior of CFT column to H-beam full-scale connection with external T-stiffener. 6 specimens whose T-stiffeners which are compounded of vertical element and horizontal element were made under the parameter of the strength ratio of each elements(vertical element and horizontal element in T-stiffener) to the beam full plastic moment. The analysis-parameters demonstrated in the base of the data that we get in experiment are strength stiffness, and plastic rotational capacity. All of specimen showed stable hysteretic behavior, and the horizontal element is more critical than vertical element in strength and stiffness. The mean beam plastic rotation of all specimen except the TS-2 specimen is 2.97% rad.

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Visualization of Surface Deformation on an Open-Hole Specimen Based on Grating Shearography

  • Lee, Jung-Ryul;Lee, Seung-Seok;Chung, Won-Seok
    • Journal of the Korean Society for Nondestructive Testing
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    • v.27 no.6
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    • pp.563-575
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    • 2007
  • This contribution contained the classical work of an open-hole tensile plate to demonstrate the performance of grating shearography and to compare with the results obtained by other full-field measurement techniques, The isotropic plate with an open-hole has often appeared in the previous contributions introducing novel full-field method and system. Grating shearography directly provided six quantitative measurands about the specimen's surface kinematics by using a single measurement set: three in-plane strains, in plane rotation, and two out-of-plane slopes. The quasi-plane wavefront of grating metrology led to high signal-to-noise ratio (SNR) and thus neither fitting nor filtering was applied, and the small shearing distance of $101{\mu}m$ could be used. The small shearing distance provided the outstanding spatial resolution of $80{\mu}m$ and sensitivity appropriate for experimental mechanics. Finally, the grating shearography enabled the visualization of the complex surface deformation around the hole and also detected parasitic flexions of the specimen in the micrometer regime during the tensile test.

A Study on the Fracture Stress in Miniaturized Charpy Impact Specimens (소형 샤르피 충격시험편에서의 파괴응력에 관한 연구)

  • Nahm, Seung-Hoon;Kim, Am-Kee;Lee, Dae-Yeol;Kim, Si-Cheon
    • Proceedings of the KSME Conference
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    • pp.132-137
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    • 2001
  • Miniaturized specimen technology is useful to characterize the mechanical behavior using a minimum volume of material, because it is almost impossible to sample the conventional specimen for the fracture toughness test without damage to equipment. Test material was 1Cr-1Mo-0.25V steel which was widely used for turbine rotor material. Two kinds of miniaturized impact specimens were prepared, i.e., miniaturized specimen with side groove and without side groove. The correlation between ductile brittle transition temperature(DBTT) of full size impact specimen and that of miniaturized impact specimen was made. The characteristics of miniaturized impact specimens technique as well as fracture stress were discussed. Finally, we concluded that the characteristics of fracture stress change on aging time were similar to that of DBTT.

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Thermal Strain Measurement of Austin Stainless Steel (SS304) during a Heating-cooling Process

  • Ha, Ngoc San;Le, Vinh Tung;Goo, Nam Seo;Kim, Jae Young
    • International Journal of Aeronautical and Space Sciences
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    • v.18 no.2
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    • pp.206-214
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    • 2017
  • In this study, measurement of thermophysical properties of materials at high temperatures was performed. This experiment employed a heater device to heat the material to a high temperature. The images of the specimen surface due to thermal load at various temperatures were recorded using charge-coupled device (CCD) cameras. Afterwards, the full-field thermal deformation of the specimen was determined using the digital image correlation (DIC) method. The capability and accuracy of the proposed technique are verified by two experiments: (1) thermal deformation and strain measurement of a stainless steel specimen that was heated to $590^{\circ}C$ and (2) thermal expansion and thermal contraction measurements of specimen in the process of heating and cooling. This research focused on two goals: first, obtaining the temperature dependence of the coefficient of thermal expansion, which can be used as data input for finite element simulation; and second, investigating the capability of the DIC method in measuring full-field thermal deformation and strain. The results of the measured coefficient of thermal expansion were close to the values available in the handbook. The measurement results were in good agreement with finite element method simulation results. The results reveal that DIC is an effective and accurate technique for measuring full-field high-temperature thermal strain in engineering fields such as aerospace engineering.

A Structural Performance Test of a Full-scale Pretension PSC Girder (실물모형 프리텐션 PSC 거더의 구조성능 시험)

  • Kim, Tae Kyun;Lee, Doo Sung;Lee, Sung Chul
    • Journal of The Korean Society of Civil Engineers
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    • v.33 no.5
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    • pp.1741-1751
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    • 2013
  • The main purpose of this study is to investigate the static behavior of a prestressed concrete (PSC) girder using pre-tension method. A 30m long full-scale pretension PSC girder is fabricated by the portable fabrication system and tested. All results have been compared to those obtained from F.E.A results. Deflections at the middle of girders have been measured for evaluation. Also, strains of concrete at the middle of span have been measured. From the results of experimental, the load when initial crack was developed was obtained to be 1.75 time the unfactered design load in the full-scale girder specimen. Also, the data of specimen are satisfied the desgin requirements of ductility on the Korea Bridge Design Specification(2010). In service state, the vertical deflection at center of test specimen when a initial crack was developed is satisfied the vertical deflection requirement under live load of the Korea Bridge Design Specification(2010). To verify the experimental results, we numerical analyze the test and confirmed that the data were similar with results from the test above. The pretension girder fabricated in site were found to have enough strength for safety under and after construction.

The analysis on the shape of a Standard Test Specimen for the Torsion Test and The Effects of Misalignments (비틀림 시험에 대한 표준시험시편 형상 및 축 정렬 이상 영향 분석)

  • Kim, Ju-Hee;Kim, Yun-Jae;Park, Chi-Yong;Heo, Yong-Hak;Je, Jin-Ho
    • Proceedings of the KSME Conference
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    • pp.155-160
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    • 2008
  • Using a three-dimensional (3-D) FE analyses, this paper provides the shape optimization of the standard test specimen for the torsion test, as well as a method for analyzing effects of misalignment under the angular and concentric misalignment. For verification, FE analysis is performed, which is designed for the perfectly full-model. To optimize the design shape of the torsion-controlled fatigue test specimen, we performed sensitivity analysis using shape parameters. Additionally, two kinds of misalignment (angular misalignment and concentric misalignment) are applied to the circular and tubular specimens to show effects of misalignments in the FE analysis. The present results will provide valuable information for designing shafts for every kind of mechanical system under torsional force.

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