• Title/Summary/Keyword: Specimen

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An Experimental Study on the Compressive Strength Characteristics of Reinforced Concrete Columns Strengthened with Fiber Sheets (섬유시트로 보강된 철근콘크리트 기둥의 압축강도 특성에 관한 실험적 연구)

  • Kim, Jeong-Sup;Choi, Jin-Seok;Cho, Cheol-Hee;Go, Song-Kyoon
    • Journal of the Korea Institute of Building Construction
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    • v.3 no.2
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    • pp.119-127
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    • 2003
  • Test specimen test was performed using concrete reinforced with fiber sheet and the test variables were based on the kinds of fiber and the number of reinforcement layers. Using steel-concrete reinforced with fiber sheet, compression tests were performed and the test variables were the kinds of fiber, number reinforcement layers and reinforcement layer order. The following results were obtained: 1) It was demonstrated that compressive strength of the test specimen reinforced during test specimen test and member test increased as the number of reinforcement layers increased. 2) It was shown that non-reinforced test, specimen were destroyed during the member tests, but the specimen reinforced with CFS destroyed and the GFS-reinforced specimen and composite reinforced specimen showed ductile destruction. 3) As a result of tests on kinds of reinforcement fiber, it was demonstrated that CFS-reinforced test specimen had higher compressive strength in a 공시체 test. In the member test, 2ply-and 3ply-GFS reinforced specimens except lplied one had higher compressive strength. It was because partial destruction occurred due to the rate of height/section. 4) For layer strength order, compared with test specimen reinforced only with a single reinforced material, test specimen reinforced with CFS and GFS, and test specimen reinforced with CFS first showed better results in compressive strength and ductility judgement.

A Study on the Low-Cycle Fatigue Behavior for Thermally-Aged 304 Stainless Steel (시효영향에 따른 304스테인리스강의저 사이클 피로 거동에 관한 연구)

  • Baek, Nam-Ju;Lee, Sang-Mae;Lee, Min-U
    • Journal of the Korean Society for Precision Engineering
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    • v.4 no.1
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    • pp.53-64
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    • 1987
  • Low Cycle fatigue data through stress controlled and strain controlled tests at room temperature were obtained for solution treated and thermally aged 304 stainless steel. All the tests were conducted with the greguency, 1Hz of stress controlled and the strain rate, 40%/min of strain controlled. The aged specimen had the longer fatigue life at the lower stresses than at the higher stresses. It is shown that the fatigue limit of the aged specimen was a little higher than that of the solution treated specimen. It is considered to be due to the presence of carbide precipitates at grain boundary which depressed the crack propagation. The aged specimen showed the larger alternating stress and the more rapid cyclic work harding than the solution treated specimen. Bauschinger effect of the aged specimen was not pronounced than that of the solution treated specimen.

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Effect of Grain Size on the Ballistic Performance of Alumina Ceramics (알루미나의 방탄특성에 대한 입경의 영향)

  • 백용기;강을손;정동익;최원봉
    • Journal of the Korean Ceramic Society
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    • v.29 no.4
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    • pp.312-318
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    • 1992
  • Two kinds of alumina specimens with different grain size (1 and 51 $\mu\textrm{m}$) but same density were prepared by hot-pressing. Fracture strength and fracture toughness of these specimens at low strain rate, sonic velocity, and elastic property were evaluated. Ballistic performance against Cal. 50 AP projectile was characterized by thick-backing method by using A16061-T6 reference block. Mechanical properties measured at low strain rate showed that the specimen with samll grain (SG) were better than specimen with large grain (LG). Fracture strength and fracture toughness of LG specimen were 131 MPa and 3.01 MPa{{{{ SQRT { m} }}, but those of SG specimen were 349 and 4.23, respectively. Sonic velocity and elastic properties of these specimen were similar, but bulk velocity and bulk modulus were different at amount of 4 and 9%. The tendency of ballistic performance was not consistent with the mechnaical properties at low strain rate. The ballistic performance based on quantitative efficiency revealed that the LG specimen (5.13) was ballistically better than the SG specimen (4.00) in spite of their lower mechanical properties.

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Statistical Analysis for Fatigue Lifetime of Ceramics (세라믹스의 피로수명에 대한 통계적 분석)

  • 박성은;김성욱;이홍림
    • Journal of the Korean Ceramic Society
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    • v.34 no.9
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    • pp.927-934
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    • 1997
  • Static and cyclic fatigue tests were carried out for alumina specimen to study the statistical analyses (normal, lognormal and Weibull distribution) of fatigue lifetime data and nominal initial crack length data. Fatigue lifetime data followed Weibull distribution better than normal or lognormal distribution, for the shape parameter of the notched specimen was larger than that of the unnotched specimen. The nominal initial crack length data obtained from fatigue lifetime followed the lognormal and Weibull distribution better than normal distribution, for the coefficient of variation of the unnotched specimen was larger than that of the notched specimen, and shape parameter of unnotched specimen was smaller than that of the notched specimen.

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An Experimental Study on the Properties of Porous Concrete according to Correction Factor and Specimen Thickness (보정계수 및 시험체두께가 포러스콘크리트의 기초물성에 미치는 영향에 관한 실험적 연구)

  • 김재환;이성일;장종호;오시덕;박정호;김무한
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2002.11a
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    • pp.55-58
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    • 2002
  • This study is to analyze the influence of correction factor and specimen thickness on the fundamental properties of porous concrete. Results of this study were shown as follows; 1) As correction factor decrease, compaction time according to correction factor and specimen thickness decrease. Also, though correction factor is same, as specimen thickness increase, compaction time increase. So It mutt be considered that the influence of compaction time according to correction factor and specimen thickness. 2) As correction factor decrease, difference of measured thickness and designed thickness according to correction factor and specimen thickness decrease. Also, correction factor of aggregate of 10~l5mm is smaller than that of 5~l0mm. So It must be considered that the influence of correction factor according to size of aggregate.

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Residual Voltage Properties of EPR Cables and Sheets (EPR케이블과 시트의 잔류전압 특성)

  • Lee, Sung-Ill;Bae, Duck-Kweon;Kim, Min-Ho;Song, Kee-Tae;Lee, Won-Jae;Oh, Yong-Chul;Joo, In-Kyu
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.11a
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    • pp.291-292
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    • 2008
  • This study used EPR's sheet and cable as a specimen, and measured residual voltage depending on the induced voltage, thickness of the sheet, and shape of the sheet and cable. The results of the study lead to the following conclusion: 1) The residual voltage increased in proportion to the induced voltage as time increases; 2) The residual voltage of the basic mixed specimen and practical mixed specimen increased as time increased; 3) The peak of the cable appeared earlier than that of the sheet in both of the basic mixed specimen and practical mixed specimen.

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Tensile Characteristics of ETFE Film According to the Specimen Type (시험편 형상에 따른 ETFE 필름재의 인장 특성)

  • Kim, Seung-Deog;Chu, Seok-Beom;Jang, Myung-Ho;Lee, Jeong-Hyun
    • Journal of Korean Association for Spatial Structures
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    • v.17 no.4
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    • pp.159-165
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    • 2017
  • In this paper, uniaxial tensile tests of ETFE films with three kinds of thicknesses(100, 200, $250{\mu}m$) and two kinds of directions(machine direction & transverse direction) are performed and the tensile strength, the tensile strain at break and the Young's modulus of ETFE films are compared for two kinds of specimen types(2 & 5). It could be figured out that there are no significant difference between tensile strengths of two specimen types but the tensile strain at break and the Young's modulus of ETFE films are affected by the specimen types. And it is concluded that the uniaxial tensile test of specimen type 2 are more reliable than that of specimen type 5.

Effects of Specimen Depth on Flexural Compressive Strength of Concrete (부재의 깊이가 콘크리트의 휨압축강도에 미치는 영향)

  • 이성태;김진근;김장호
    • Journal of the Korea Concrete Institute
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    • v.12 no.5
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    • pp.121-130
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    • 2000
  • Currently, in evaluating a flexural strength of a concrete member, the effect of specimen depth has not been systematically studied, even though its effect on ultimate strength of a section is very important. For all types of loading conditions, the trend is that the strength of a member tends to decrease when the member depth increases. In this study, the influence of specimen depth on flexural compressive strength of concrete member was examined experimentally. A series of C-shaped specimens subjected to axial compressive force and bending moment were tested using three geometrically similar specimens with different length-to depth ratios (h/c = 1, 2 and 4) which have compressive strength of 55 MPa. The results indicate that the flexural compressive strength decreased as the specimen depth increased. A model equation was derived based on regression analyses of the experimental data. Also, the results show that ultimate strain decreases as the specimen depth increases. Finally, a general model equation for the depth effect is proposed.

A study on DC breakdown strength due to variation of specimen shape of epoxy/SiO$_{2}$ compound material treated with silane coupling agent

  • 김명호;김재환;김경환;박찬옥;손인환;박재준
    • Electrical & Electronic Materials
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    • v.5 no.4
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    • pp.393-399
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    • 1992
  • In order to increase the coupling strength between bisphenol-A type epoxy resin and filler SiO$_{2}$ it was treated to filler with silane coupling agent[KBM-603]. To observe how silane coupling agent effects on dielectric breakdown strength of Epoxy/SiO$_{2}$ compound material, specimens of eight type were made like following. (A-1, A-2), (B-1, B-2), (C-1, C-2), (D-1, D-2) (see 2-2. Specimen) Specimen treated with silane coupling agent had always bigger dielectric breakdown strength than non-treated specimen. Under the influence of silane coupling agent, increment ratio of dielectric breakdown strength at specimen manufactured by hand drill was very bigger than that of specimen inserted spherical electrode. Therefore, as the specimen shape was varied, it was studied on effect that silane coupling agent affects on dielectric breakdown strength of Epoxy/SiO$_{2}$ compound material.

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A Probabilistic Study to the Effect of Specimen Thickness on Fatigue Crack Growth Resistance (피로균열전파저항에 미치는 시험편 두께의 영향에 관한 확률론적 연구)

  • 김선진;오세규
    • Journal of Ocean Engineering and Technology
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    • v.8 no.2
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    • pp.47-55
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    • 1994
  • The purpose of the present study is to investigate the effect of specimen thickness on statistical properties of crack growth resistance. In this study, the resistance S$\delta$$_h$(x) to fatigue crack growth was treated as a spatial stochastic process. which varies randomly on the crack surface. The theoretical autocorrelation functions of the resistance to fatigue crack growth considering specimen thickness are discussed for several correlation lengths. The main results obtained are : (1) The theoretical autocorrelation functions of S$\delta$$_h$(x) are almost independent of specimen of specimen thickness except for the origin. (2) The variance increases with decreasing specimen thickness.

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