• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2011.04a
• /
• pp.648-651
• /
• 2011

본 논문에서는 3차원 섬유분포를 가정하여 고유동 섬유보강 시멘트 모르타르의 유동에 따른 섬유방향성변화를 해석적으로 파악해 보았다. 유동흐름은 평면상의 2차원 완전발달 전단흐름을 고려하였다. 유동에 따른 섬유의 회전운동은 섬유간의 상호 간섭효과를 무시한 Jeffery의 기본식에 근거하였다. 굳지 않은 섬유혼입 모르타르의 유동에 따른 섬유방향성 분포 변화를 흐름선과 동일 유동거리 상의 단면에 대해 파악하였다. 그 결과, 단면 내 위치에 따라서 섬유방향성 분포 변화가 크게 차이가 발생하는 것을 확인할 수 있었다. 또한 유동거리에 따른 단면상의 섬유방향성 분포는 초기 유동거리에서 분포 형상에 큰 변화가 발생하였고, 유동에 따라 섬유가 유동방향과 나란하게 놓이는 경향이 커지는 것을 확인할 수 있었다. 이러한 섬유방향성 변화의 예측은 섬유보강 시멘트 복합체의 인장특성에 예측하는데 유용하게 사용될 것이다.

• Journal of the Korea Concrete Institute
• /
• v.20 no.6
• /
• pp.731-739
• /
• 2008

To evaluate the fiber orientation characteristics and estimate its effect on the flexural strength of steel fiber reinforced ultra high strength concrete with directions of concrete placing, we developed an image processing technique and carried out the flexural test to quantify the effect of fiber orientation characteristics on the flexural strength as well. The image processing technique developed in this study could evaluate quantitatively the fiber orientation property by the use of dispersion coefficient, the number of fibers in a unit area, and fiber orientation. It was also found that the fiber orientation characteristics were dependent on the direction of concrete placing. Fiber orientation characteristic was revealed to strongly affect the ultimate flexural strength, while hardly affecting the first cracking strength. Theoretical model for flexural strength was applied to compare with test results, which exhibited a good agreement.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.22 no.6
• /
• pp.639-646
• /
• 2009

High-flow steel-fiber reinforced mortar may induce a certain fiber orientation distribution in the process of placing and thus have an influence on the tensile properties. In this paper, the variation of the fiber orientation distribution according to the flow of high-flow steel-fiber reinforced mortar was estimated in numerical simulation. The analytical results present that the major variation of fiber orientation distribution is made within 150mm of flow distance, thereafter the tendency of the fiber orientation distribution is not noticeable even though the peak of distribution density in the orientation parallel to the flow direction get bigger along the distance. Considering the close relation between the fiber orientation and the tensile behavior of composite, prediction of fiber orientation distribution make it possible to predict the variation in the tensile behavior of high-flow steel-fiber reinforced mortar according to the flow.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.22 no.6
• /
• pp.157-163
• /
• 2018

This study is aimed at controlling the fiber orientation and improve the fiber distribution in fiber-reinforced cement composites using blades that can be placed inside the existing nozzles. To optimize the blade parameters, multi-physics finite element analysis was performed that could account for the flow of the cementitious matrix material, the movement of the entrained fibers, and the interactions with the nozzle. As a result, this study defined the blade distance, length, and position as a function of the fiber length to be used in the field. The blades with a distance from 1.2 to 2.4 times the fiber length and length from 4 to 8 times the fiber length, as well as located at below 14 times the fzfiber length from the nozzle exit maintained the fiber orientation angle less than $5^{\circ}$. In addition, the blade-type nozzle proposed in the study can be attachable and detachable to the conventional casting equipment, and thus it can provide the usability and convenience in practical applications.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.483-484
• /
• 2010

In this paper, it was intended to understand the effect of the fiber orientation distribution on the tensile behavior of Intra High Performance Cementitious Composites (UHPCC) and to estimate flow-dependent fiber orientation distribution and the corresponding tensile behavior of UHPCC.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.491-492
• /
• 2009

This paper presents evaluation results of fiber dispersion, number of fibers in a unit area, fiber orientation according to the mix-proportion of ECC and bridging stress calculated on the basis of fiber distribution characteristics.

• Magazine of the Korea Concrete Institute
• /
• v.25 no.3
• /
• pp.39-42
• /
• 2013

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.8
• /
• pp.88-95
• /
• 1996

유리섬유가 강화된 열가소성 복합재료 판재의 성형성에 대한 이해를 돕기 위해 이론적 고찰과 실험적 고찰이 행해졌다. 성형시험에서 사용된 형상은 임의의 방향으로 위치한 유리섬유를 중량비로 30% 함유한 폴리프로필렌 재료가 사용되었고, 시험된 형상은 판재의 굽힘성이나 인장성을 측정하는데 널리 사용되는 스위프트컵(Swift flat-bottomed cup)모양이다. 성형시험과 재료시험은 플리프로필렌 Matrix의 유리성 천이온도(Glass transition temperature)와 용융온도 사이에서 행해졌다. 본 연구의 이론과 고찰을 위해서 재료의 평면 방향으로는 동질성을 그리고 그 직각 방향으로는 이질성을 가진 연속체 물질로 가정하여 유도하였다. 이러한 이론적 결과는 실험 결과와 비교되어졌고,이를 통해 시험된 재료의 최적의 성형조건을 제시하였다.

• Proceedings of the Korean Fiber Society Conference
• /
• 1997.10a
• /
• pp.404-410
• /
• 1997

• Proceedings of the Korean Fiber Society Conference
• /
• 1995.10a
• /
• pp.103-103
• /
• 1995