• International Journal of Concrete Structures and Materials
• /
• 제5권2호
• /
• pp.87-96
• /
• 2011

Many studies have been performed on steel fiber-reinforced normal/high-strength concrete (SFRC, SFRHC) for years, which is to improve some of the weak material properties of concrete. Most of equations for material strengths of SFRHC, however, were proposed based on relatively limited test results. In this research, therefore, the material test results of SFR(H)C were extensively collected from literature, and material tests have conducted on SFR(H)C; compressive strength tests, splitting tensile tests, and modulus of rupture tests. Based on the extensive test data obtained from previous studies and this research, a database of SFR(H)C material strengths has been established, and improved equations for material strengths of SFR(H)C were also proposed. Test results showed that both the splitting tensile strength and the modulus of rupture of SFR(H)C increased as the volume fraction of steel fiber increased, while the effect of the steel fiber volume fraction on the compressive strength of SFR(H)C were not clearly observed. The proposed equations for the splitting tensile strength and the modulus of rupture of SFR(H)C showed better results than the previous equations examined in this study in terms of not only accuracy but also safety/reliability.

• Computers and Concrete
• /
• 제3권4호
• /
• pp.197-212
• /
• 2006

Modeling of physically non-linear behavior becomes more and more important for the analysis of SFRC structures in practical applications. From this point of view we will present an effective, three-dimensional constitutive model for SFRC, that is also easy to implement in commercial finite element programs. Additionally, the finite element analysis should only require standard material parameters which can be gained easily from conventional experiments or which are specified in appropriate building codes. Another important point is attaining the material parameters from experimental data. The procedures to determine the material parameters proposed in appropriate codes seem to be only approximations and are unsuitable for precise structural analysis. Therefore a finite element analysis of the test itself is used to get the material parameters. This process is also denoted as inverse analysis. The efficiency of the proposed constitutive model is demonstrated on the basis of numerical examples and their comparison to experimental results. In the framework of material parameter identification the idea of a new, indirect tension testing procedure, the "Modified Tension Test", is adopted and extended to an easy-to-carry-out tension test for steel fiber reinforced concrete specimens.

• 한국안전학회지
• /
• 제16권2호
• /
• pp.44-50
• /
• 2001

The rotated bending fatigue test was conducted in air md in 3.5% NaCl salt solution to investigate the fatigue fracture behaviour of raw material and F.E.M dual phase steel made from raw material(SS41) by a suitable heat treatment. This study has compared the initial microcrack creation of material by tensile test with that by fatigue test. And the rotated bending test of cantilever type under the condition of 3.5% NaCl salt solution and air has investigated the corrosion fatigue fracture behaviour with the variation of stress concentration factor determined by each of notch shapes. The initial microcrack have been developed in fragile grainboundary with general corrosion occurring in raw material : in the pits built up by corrosion in F.E.M. dual phase steel because pits bring out stress concentration. It is small that the degree of decrease in corrosion fatigue life for F.E.M. dual phase steel compared with raw material because the notch sensitivity of F.E.M. dual phase steel is lower than raw material in reason of characteristics with two-phase construction.

• 한국마이크로전자및패키징학회:학술대회논문집
• /
• 한국마이크로전자및패키징학회 2007년도 SMT/PCB 기술세미나
• /
• pp.37-47
• /
• 2007

Factor : Structure Metal pad & SMO size Board level TC test : - Large SMO size better Board level Drop test : - Large SMO size better Factor : Structure Substrate thickness Board level TC test : - Thick substrate better Board level Drop test : - Substrate thickness is not a significant factor for drop test Factor : Material Solder alloy Board level TC test : - Not so big differences over Pb-free solder and NiAu, OSP finish Board level Drop test : - Ni/Au+SAC105, CuOSP+LF35 are better Factor : Material Pad finish Board level TC test : - NiAu/NiAu is best Board livel Drop test : - CuOSP is best Factor : Material Underfill Board level TC test - Several underfills (reworkable) are passed TCG x500 cycles Board level Drop test : - Underfill lots have better performance than non-underfill lots Factor : Process Multiple reflow Board level TC test : - Multiple reflow is not a significant actor for TC test Board level Drop test : N/A Factor : Process Peak temp Board level TC test : - Higher peak temperature is worse than STD Board level Drop test : N/A Factor : Process Stack method Board level TC test : - No big difference between pre-stack and SMT stack Board level Drop test : - Flux dipping is better than paste dipping but failure rate is more faster

• 한국강구조학회 논문집
• /
• 제23권4호
• /
• pp.515-522
• /
• 2011

본 연구의 목적은 시험적 방법을 통해 SHN400 강재의 소재 특성이 건축구조용 강재로 적합한지를 평가하는 것이다. 이를 위해 국내에서 생산되는 열간 압연 H형강 중 최대 춤 및 최대 플랜지 두께의 H형강과 SHN400 강종의 주요 사용처가 될 보부재로 수요가 많은 H형강 규격을 대상으로 화학성분 평가, 인장강도, 매크로, 미크로 및 샤르피 충격 시험을 실시하였다. 각 시험은 관련 KS 규격에서 요구하는 시험 조건하에서 수행되었으며, 시험 결과 화학성분 및 기계적 특성과 관련된 모든 시험에서 SHN400 강종은 KS 규격(KS D 3866)의 요구 조건과 내진설계시 강재에 요구되는 조건들을 만족하는 것으로 나타났다. 특히 용접성과 관련된 탄소당량(Ceq)과 비탄성 변형능력과 관련된 항복비의 경우 KS 규격을 상회하는 결과를 나타내었다. 따라서 SHN400 강재는 소재 특성 측면에서 건축구조용 강재에 적합한 것으로 판단된다.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2018년도 추계 학술논문 발표대회
• /
• pp.193-194
• /
• 2018

In this study, various materials such as epoxy material, urethane material, cement material, and acrylic material are used to solve the water leakage occurring in underground structures. However, in the reality that the durability is insufficient and the effect is insufficient, it is aimed to improve the repairing effect by using acrylics. As a second study, it is confirmed that leachate can be used as a repair material by considering long time under water stability, elongation range test, fatigue resistance test, tube stability test, damage recovery performance ana temperature stability considering leakage environment for polyacrylate. In addition, this material is applied to Expansion Joint to perform leakage repair, and to verify the effect of repairing leakage by monitoring and visual observation of concrete humidification.

• Elastomers and Composites
• /
• 제42권1호
• /
• pp.32-46
• /
• 2007

고무부품의 신뢰성을 확보하기 위해서 고무재료의 기계적 물성을 정확히 파악하는 것이 매우 중요하다. 본 연구에서는 천연 및 합성고무에 대해 다양한 환경조건에서 물성시험을 수행하여 경도, 신율 및 응력-변형률 관계와 동 특성을 파악하였다. 또한, 고무부품의 유한요소 해석에 필요한 비선형 재료상수를 단축인장과 이축인장시험을 통해 결정하였다.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
• /
• pp.151-152
• /
• 2019

This study length variation test, shock test were conducted to evaluate the performance of synthetic resin form. Results of both thermal length variation test and shock test satisfied the KS standards. for length variation test, the result of the horizontal and vertical valuse were -0.1% in average.

• 한국도로학회논문집
• /
• 제16권6호
• /
• pp.121-128
• /
• 2014

PURPOSES : The objective of this study is to evaluate the tack-coating material's properties using the bitumen bond strength(BBS) test and damping test as function of changed curing times. In this study, bonding strength tests were performed according to the curing time of tack coating materials. METHODS : In order to investigate bonding characteristic of tack coating materials, the Pneumatic Adhesion tensile Testing Instrument(PATTI) device is used to measure the bond strength between the tack coating materials and aggregate substrate based on the AASHTO TP-91. Also, damping test as in situ test was used to determine an appropriate traffic openting time for construction vehicle. Four different tack-coating materials were used in this study. The BBS tests were performed a one hour curing and testing temperatures of $5^{\circ}C$, $15^{\circ}C$, and $25^{\circ}C$. Damping test was conducted at 30min, 60min, 90min, and 120 min of curing times with temperatures of $20^{\circ}C$ and $30^{\circ}C$. RESULTS and CONCLUSIONS : The BBS test results show various bond strength as function of tack coat materials. At the same testing condition, A tack coat material shows almost two times higher than D tack coat materials although both materials are satisfied the criteria of material's physical properties. Also, Dampting test results shows similar trend with BBS test result. The damping test result was significantly changed as function of tack coat materials. Based on this study, the tack coating material's curing time is very important. Therefore, both curing time and the bond strength's characteristic has to be considered in standard specification.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 추계학술대회논문집A
• /
• pp.105-110
• /
• 2000

The Micromechanics test is new test method which uses comparatively smaller specimen than that required in conventional material tests. There are several methods, such as small-specimen creep test, the continuous indentation test, and small punch(SP) test. Among them, the small punch(SP) test method has been applied to many evaluation fields, such as a ductile-brittle transition temperature, stress corrosion cracking, hydrogen embrittlement, and fracture properties of advanced materials like FGM or MMC. In this study, the small punch(SP) test is performed to evaluate the mechanical properties at high/low temperature from $-196^{\circ}C$ to $650^{\circ}C$ and the material degradation for virgin and aged materials of 9Cr1MoVNb steel which has been recently developed. The ${\Delta}P/{\Delta}{\delta}$ parameter defined a slope in plastic membrane stretching region of SP load-displacement curve decreases according to the increase of specimen temperature, and that of aged materials is higher than the virgin material in all test temperatures. And the material degradation degrees of aged materials with $630^{\circ}C$ -500hrs and $630^{\circ}C$ -1000hrs are $36^{\circ}C$ and $38^{\circ}C$ respectively. These behaviors are good consistent with the results of hardness($H_v$) and maximum displacement(${\delta}_{max}$).