• Title/Summary/Keyword: 압축시험

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A Study on Field Testing Methods of Compressive Strength for Shotcrete Quality Control (숏크리트 품질관리를 위한 현장 압축강도시험법에 관한 연구)

  • Chang Seok-Bue;Hong Eui-Joon;Moon Sang-Jo
    • 한국터널공학회:학술대회논문집
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    • 2005.04a
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    • pp.175-186
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    • 2005
  • 터널공사에서 숏크리트는 가장 중요한 지보재 이므로 시공중 품질관리를 위한 압축강도시험은 매우 중요하다. 현장 타설 숏크리트의 압축강도는 실험실조건에 비하여 낮은 값을 갖고 있어 현장강도 시험은 필수적이나, 적절한 시험방법의 부재로 인하여 코어채취에 의한 압축강도시험이 적용되고 있다. 이 방법은 적절한 샘플채취와 초기강도 측정에 큰 문제점을 가지고 있다. 따라서, 본 논문에서는 공기압식 핀관입시험법을 고찰하였으며, 압축강도시험의 단점을 해소할 수 있는 점하중강도시험법의 적용성을 검토하였다. 또한, 향후 연구계획으로써, 현장강도시험기법으로 선정된 공기압식 핀관입시험기의 적정성 평가와 숏크리트 압축강도시험을 대체할 수 있는 점하중강도시험의 적용성 분석계획을 제시하였다.

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Evaluation of Rock Uniaxial Compressive Strength Using Ultrasonic Velocity (초음파 속도를 이용한 암석의 일축압축강도 평가)

  • Baek, Seung-Cheol;Kim, Yong-Tae;Kim, Hong-Taek;Yoon, Jun-Sig;Lee, Yun-Gyu
    • Journal of the Korean GEO-environmental Society
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    • v.7 no.2
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    • pp.33-42
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    • 2006
  • Eighteen biotite granites on Andong area and twenty seven igneous rocks(diorite, granite, andesite, rhyolite) on Yeosu area were tested to evaluate the correlations between the uniaxial compressive strength values, as determined by the standard uniaxial compression test, and the corresponding results of the ultrasonic velocity. The variability of test results for each test was evaluated by calculating the coefficient of determination or variation. Results indicate that strong correlations exist between the results of uniaxial compression vs the point load, Schmidt hammer and ultrasonic velocity test. The correlation equations for predicting compressive strength using different methods are presented along with their confidence limits. Ultrasonic velocity test used provide reliable estimates of compressive strength.

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Vibration Analysis of a Turbo Compressor Test Rig (터보 압축기 성능시험을 위한 리그 진동 분석)

  • Park, Tae-Choon;Kang, Young-Seok;Yang, Soo-Seok;Lee, Jin-Kun
    • Aerospace Engineering and Technology
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    • v.8 no.1
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    • pp.98-107
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    • 2009
  • Vibration analysis of a turbo compressor test rig was carried out in order to investigate the vibrational characteristics of the compressor facility in KARI before conducting the compressor performance test of 5MW-class gas turbine engine for generation. The overall compressor test facility consists largely of inlet and exit ducts, a test section and a driving part. Vibration was measured with accelerometers at the test section and the driving part, especially at a main housing, a collector, a bearing carrier, a torquemeter, a gearbox, and an electric motor. Gap sensors are also installed to measure the rotordynamic characteristics of compressor shaft.

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Evaluation of Impact Damage and Residual Compression Strength after Impact of Glass/Epoxy Laminate Composites for Lightweight Bogie Frame induced by Ballast-Flying Phenomena (도상자갈 비산에 의한 경량 대차프레임 적용 유리/에폭시 적층 복합재의 충격손상 및 충격 후 잔류압축강도 평가)

  • Goo, Jun-Sung;Shin, Kwang-Bok;Kim, Jung-Suk
    • Journal of the Korean Society for Railway
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    • v.15 no.2
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    • pp.109-115
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    • 2012
  • In order to evaluate the effect of structural degradation of a GFRP composite bogie frame due to ballast-flying phenomena, the impact test and residual compression test after impact was conducted for glass fiber/epoxy 4-harness satin woven laminate composites applied to skin part of a bogie frame. The impact test was performed using a instrumented impact testing system with energy levels of 5J, 10J, and 20J, and the impactor was designed to have various ballast shapes such as sphere, cube, and cone to consider the ballasted track environments. The residual compression strength was tested to evaluate the degradation of mechanical properties of impact-damaged laminate composites. The results showed that the damage area and the degradation of residual compressive strength after impact for laminate composites was increased with increase of impact energy for all ballast shapes, and was particularly most influenced by ballast shape of cone.

A Study on Microfailure Mechanism of Single-Fiber Composites using Tensile/Compressive Broutman Fragmentation Techniques and Acoustic Emission (인장/압축 Broutman Fragmentation시험법과 음향방출을 이용한 단섬유 복합재료의 미세파괴 메커니즘의 연구)

  • Park, Joung-Man;Kim, Jin-Won;Yoon, Dong-Jin
    • Composites Research
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    • v.13 no.4
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    • pp.54-66
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    • 2000
  • Interfacial and microfailure properties of carbon fiber/epoxy matrix composites were evaluated using both tensile fragmentation and compressive Broutman tests with an aid of acoustic emission (AE) monitoring. A polymeric maleic anhydride coupling agent and a monomeric amino-silane coupling agent were used via the electrodeposition (ED) and the dipping applications, respectively. Both coupling agents exhibited significant improvements in interfacial shear strength (IFSS) compared to the untreated case under tensile and compressive tests. The typical microfailure modes including fiber break of cone-shape, matrix cracking, and partial interlayer failure were observed during tensile test, whereas the diagonal slippage in fiber ends was observed under compressive test. For both loading types, fiber breaks occurred around just before and after yielding point. In both the untreated and treated cases AE amplitudes were separately distributed for the tensile testing, whereas they were closely distributed for the compressive tests. It is because of the difference in failure energies of carbon fiber between tensile and compressive loading. The maximum AE voltage for the waveform of carbon or basalt fiber breakages under tensile tests exhibited much larger than those under compressive tests, which can provide the difference in the failure energy of the individual failure processes.

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Experimental Investigation on the Behaviour of CFRP Laminated Composites under Impact and Compression After Impact (CAI) (충격시 CFRP 복합재 판의 거동과 충격후 압축강도에 관한 실험적 연구)

  • Lee, J;Kong, C;Soutis C.
    • Composites Research
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    • v.16 no.4
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    • pp.66-73
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    • 2003
  • The importance of understanding the response of structural composites to impact and CAI cannot be overstated to develop analytical models for impact damage and CAI strength predictions. This paper presents experimental findings observed from quasi-static lateral load tests, low velocity impact tests. CAI strength and open hole compressive strength tests using 3 mm thick composite plates($[45/-45/0/90]_{3s}$- IM7/8552). The conclusion is drawn that damage areas for both quasi-static lateral load and impact tests are similar and the curves of several drop weight impacts with varying energy levels(between 5.4 J and 18.7 J) follow the static curve well. In addition, at a given energy the peak force is in good agreement between the static and impact cases. It is identified that the failure behaviour of the specimens from the CAI strength tests was very similar to that observed in laminated plates with open holes under compression loading. The residual strengths art: in good agreement with the measured open hole compressive strengths. considering the impact damage site area, an equivalent hole. The experimental findings suggest that simple analytical models for the prediction of impact damage area and CAI strength can be developed on the basis of the failure mechanism observed from the experimental tests.

Technical Papers : Performance Test of a Two Stage Axial Compressor of a Turboshaft Engine for Helicopters (기술논문 : 헬리콥터용 터보샤프트엔진 2 단 축류압축기 성능시험)

  • Kim, Chun-Taek;Kim, Jin-Han;Yang, Su-Seok;Lee, Dae-Seong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.30 no.3
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    • pp.139-145
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    • 2002
  • 이륙중량 4000kg, 10-12인승급 다목적 헬리콥터에 적용가능한 엔진 개량 개발을 목표로 기존 헬리콥터 엔진을 개량대상으로 선정하고 이러한 다목적 헬기의 요구조건에 부합하기 위해 기존 엔진의 요소부품을 재설계하였다. 첫 단계로 최소변경으로 720 hp에서 840 hp로 출력을 증강시키기 위하여 2단 축류압축기의 기존 입구 유도익을 제거하고 익현의 길이를 증가하여 유량 및 압축비를 증가시킴으로써 출력 증강을 얻도록 재설계를 수행하였다. 이러한 2단 축류압축기의 성능을 검증하기 위하여 두 번째 단 단독시험 및 전체 2단에 대한 성능시험이 수행되었으며 첫 번째 단의 성능은 이 결과로부터 도출되었다. 성능시험결과 전체 2단 압축기는 유량 3.088 kg/s에서 압력비 2.14, 단열효율 88%의 성능을 갖는 것으로 나타났으며 압축기 출구의 압력 및 온도 분포를 레이크를 이용하여 측정하였다.

A Study on the Evaluation of Tension-Compression Fatigue Characteristics of Glass Fiber/Epoxy 4-Harness Satin Woven Laminate Composite for the Railway Bogie Application (철도차량 대차 적용 유리섬유/에폭시 4-매 주자직 적층 복합재의 인장-압축 피로특성 평가 연구)

  • Jeon, Kwang-Woo;Shin, Kwang-Bok;Kim, Jung-Seok
    • Composites Research
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    • v.23 no.5
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    • pp.22-29
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    • 2010
  • This paper describes the evaluations of tension-compression fatigue characteristics and life for glass fiber/epoxy laminate composite applied to railway bogie to reduce weight. Test samples of tension-compression fatigue were composed of glass fiber/epoxy 4-harness woven laminate composites with different stacking sequence of warp-direction, fill-direction and ${\pm}45^{\circ}$-direction. The tension-compression fatigue test was conducted with stress ratio (R) of -1 and frequency of 5Hz. Goodman diagram were used to evaluate the fatigue characteristics and life of glass fiber/epoxy 4-harness satin woven laminate composite. Anti-buckling jig was designed to prevent buckling of specimen under compression load. The test results showed that the fatigue characteristics of glass fiber/epoxy 4-harness satin woven laminate composite with stacking sequence of warp-direction had a good performance in comparison with that of SM490 used to conventional metal railway bogie.

Estimation Model of Shear Transfer Strength for Uncracked Pull-Off Test Specimens based on Compression Field Theory (비균열 인장재하 시험체의 압축장 이론에 기반한 전단전달강도 산정모델)

  • Kim, Min-Joong;Lee, Gi-Yeol
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.41 no.2
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    • pp.101-111
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    • 2021
  • Two different types of shear-friction tests were classified by external loadings and referred to as a push-off and a pull-off test. In a pull-off test, a tension force is applied in the transverse direction of the test specimen to produce a shear stress at the shear plane. This paper presents a method to evaluate shear transfer strengths of uncracked pull-off specimens. The method is based on the compression field theory and different constitutive laws are applied in some ways to gain accurate shear strengths considering softening effects of concrete struts based on Modified Compression Field Theory (MCFT) and Softened Truss Model (STM). The validity of the proposed method is examined by applying to some selected test specimens in literatures and results are compared with the predicted values. A general agreement is observed between predicted and measured values at ultimate loading stages in initially uncracked pull-off test specimens. A shear strength evaluation formula considering the effective compressive strength of a concrete strut was proposed, and the applicability of the proposed formula was verified by comparing with the experimental results in the literature.

Test and Finite Element Analysis on Compression after Impact Strength for Laminated Composite Structures of Unidirectional CFRP (일방향 탄소섬유강화 플라스틱 복합재 적층구조의 충격 후 압축강도 시험 및 유한요소해석)

  • Ha, Jae-Seok
    • Composites Research
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    • v.29 no.6
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    • pp.321-327
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    • 2016
  • In this study, tests and finite element analyses were performed regarding compression after impact strength for laminated composite structures of unidirectional carbon fiber reinforced plastic widely used in structural materials. Two lay-up sequences of composite laminates were selected as test specimens and four impact energy conditions were applied respectively. Impact and compressive strength tests were conducted in accordance with ASTM standards. Impact damages in test specimens were analyzed by using non-destructive inspection method of C-Scan, and compression after impact strengths were calculated with compressive test results. Progressive failure analysis method that can progressively simulate damages and fractures of fiber/matrix/lamina/laminate level was used for impact and compressive strength analyses. All analysis results including contact force, deflection, impact damages, compressive strengths, etc. were compared to test results, and the validity of analysis method was verified.