• Journal of the Korea institute for structural maintenance and inspection
• /
• v.9 no.1
• /
• pp.225-232
• /
• 2005

The paper presented results of the strength distributions and tension failure behaviors of splices subjected to tension forces. The bolting patterns in the tension splices are regular and staggered patterns in the research. The finite element analyses were carried out to examine the experimental results and evaluated the stress distribution patterns. The yield stresses, maximum tension stresses, stress distribution ratios, and effective net areas were analyzed through the tension experiments.

• Proceedings of the Korean Institute of Industrial Safety Conference
• /
• 2003.05a
• /
• pp.514-519
• /
• 2003

치수효과는 콘크리트나 암석과 같은 quasi-brittle 재료들의 물리적 특성에 영향을 미친다. 모든 재료의 경우에 체적이 크면 흠이 클 수 있다. 구조물의 섬유 묶음 크기가 증가하면, 섬 유 강도가 감소하는 현상을 흔히 경험해 왔다. 복합재료내의 강도 분배와 치수사이의 관계를 특성 짓는 효과적인 방법은 아직 완전하지 않다. 본 논문에서는 경험에서 얻어진 Filament Wound 튜브에 사용되는 유리 섬유와 에폭시의 인장강도 감소비율 실험데이터로 얻은 그래프로부터 Crasto와 Kim의 일방향 보강된 AS4/3501-6복합재료의 90$^{\circ}$방향 인장강도에 대한 실험결과로부터 복합재료 봉구조재의 강도 치수효과를 증명하였다.

• Composites Research
• /
• v.28 no.4
• /
• pp.197-203
• /
• 2015

Tensile properties of polypropylene based self-reinforced composites were investigated as a function of process variables of the double-belt lamination equipment such as pressure, temperature and cooling conditions. Elastic modulus was enhanced approximately 6 times from 0.2 to 1.2 GPa. The improvement mechanism was studied by identification of crystalline structure changes using DSC and XRD analysis. In addition, morphology change of self-reinforced composites was also investigated by SEM analysis in order to reveal the degree of impregnation.

• Journal of Korean Society of Steel Construction
• /
• v.25 no.1
• /
• pp.61-70
• /
• 2013

A turn-buckle is capable of adjusting the tensile force by left-hand threads and right-hand threads between tension members. There are different types of turn-buckles according to tension member and connection form but the practical and existing turn-buckles are incapable of measuring the tensile force. A turn-buckle for adjusting and measuring tensile force has therefore been developed. This study shows the ultimate strength and reliability for measurement of the new turn-buckles through finite element analysis of the developed ones. From analytic results of the new turn-buckles which have the measurement limit loads of 100kN, 200kN and 300kN, the ultimate strength is approximately five times stronger than the measurement limit capacity. Additionally, a review of the new turn-buckle, which has the measurement limit load of over 300kN, shows that there is a tendency for the size of turn-buckle to become larger. So the connection devices were designed and the loading test was conducted from the concept that the parallel connection of turn-buckle with 300kN capacity can measure the tensile force of 600kN. The results of parallel loading test show the sufficient possibility. Furthermore, the mock-up test was constructed to investigate the release of initial load and corrosion when the new turn-buckle is installed at the outdoor and exposed to rain and atmosphere.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.4 no.4
• /
• pp.489-495
• /
• 2016

In this study, the Warm-Mix Asphalt was prepared using a modified Sulfur Binder mixed with an additive of a polymer component in sulfur, which is an industrial by-product generated in the crude oil refining process. The dynamic stability and durability characteristics of the prepared Warm-Mix Asphalt was evaluated by the indirect tensile strength, the tensile strength ratio before and after water immersion and freezing-thawing, and the dynamic stability by wheel tracking test. The Warm-Mix Asphalt Mixtures using Modified Sulfur Binder has a tensile strength ratio before and after water immersion of 0.88, which is about 1.13 times that of the Warm-Mix formed modified Asphalt, and the tensile strength ration before and after freezing-thawing is also 0.82, thus, all tensile strength ratios satisfied the KS quality standard value of 0.75 or more. The indirect tensile strength was 1.6MPa which was twice the KS quality standard value of 0.8MPa, and about 1.24 times higher than that of normal heated asphalt 1.29MPa. In addition, the dynamic stability by the wheel tracking test was 14,075 times/mm, which was about 15 times higher than that of normal heated asphalt and about 3 times higher than that of the Warm-Mix formed modified Asphalt, showing excellent resistance to plastic deformation such as fatigue cracks.

• Composites Research
• /
• v.33 no.3
• /
• pp.169-175
• /
• 2020

The compression and tension test were performed to evaluate the stiffnesses of the conical composite lattice structures and results of test were compared with finite element analysis results. Because of difficulty to perform simple tension and compression test due to conical shape, suitable specimens and jig for test were made. Subelements extracted from the structure were prepared for compression test. Compression test of subelement was performed and compressive strains in fiber direction were measured. Compressive stiffness of the helical rib was verified by finite element analysis results. For stiffness of hoop rib, hoop ring specimens were extracted from the structure. Tension test of hoop ring specimen was performed to apply bending deformation to hoop rib. Stiffness of hoop rib was verified by finite element model considering various fiber volume fraction in thickness direction.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.9 no.1
• /
• pp.182-188
• /
• 2008

The compounds of recycled polyethylene(PE) and fly-ashes were prepared. Polymers used were sorted PE from mixed plastics of household waste and Low Density Polyethylene(LDPE) and Linear Low Density Polyethylene(LLDPE) recycled from the scrap of packaging film plants. Fly-ashes were from the power plant and from the household waste incinerator. The tensile strength of recycled LDPE and LLDPE compounds decreased and the flexural modulus increased with greater amount of the power plant fly-ash. Anthracite fly-ash gave rise to slightly higher tensile and flexural strength of the LLDPE mixtures than bituminous coal fly-ash presumably due to higher content of unburned carbon. The incinerator fly-ash introduced to household waste PE enhanced both tensile strength and flexural modulus of the compounds. When LDPE and household waste PE were used together, the synergistic effect of incinerator fly-ash to household waste PE was offset by reduced crystallization of LDPE due to the filler particle. The compounds of household waste PE and incinerator fly-ash might be applied to structural materials for such as sewage pipe, which reduces the waste treatment cost and conserve the environment and resources.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2009.04a
• /
• pp.488-491
• /
• 2009

본 논문에서는 응력함수와 Kantorovich method를 이용하여 기저판(substrate)에 인장과 굽힘이 작용할 때 복합재 패치의 3차원 응력을 해석하였다. 면내 방향과 면외 방향의 두 응력함수에 가상 공액일의 법칙(Complementary virtual work principle)을 적용하였으며 복합재 패치의 자유 경계조건과 바닥의 기저판으로부터 전달되는 전단 수직 응력 조건을 부여하였다. 이를 통해서 패치 구조물의 지배방정식을 연립 미분 방정식 형태의 고유치 문제로 변환하여 응력함수를 구하였다. 위 방법의 타당성과 효용성을 검증하기 위한 수치 예제로 cross-ply, angle-ply, quasi-isotropic의 패치 적층 배열을 고려하였으며, 층간 응력함수 값이 자유 경계에서 최고치를 나타내고 패치 중심부로 갈수록 급격히 감소하는 모습을 확인하였다. 제안된 기법은 기저판에 인장하중이 작용하는 경우뿐만 아니라 굽힘 하중이 작용하는 경우에도 정확한 예측이 가능하여, 패치 구조물의 층간 응력을 포함한 3차원 응력을 해석하는데 있어서 효율적인 해석 도구로서 사용할 수 있을 것이라 사료된다.

• Transactions of the Korean hydrogen and new energy society
• /
• v.34 no.1
• /
• pp.32-37
• /
• 2023

In this study, in order to propose a integrity evaluation for type IV high aspect ratio hydrogen storage vessel, a numerical analysis of the hoop tensile test and pressure test was performed using FEM software, and the results of the actual physical property test were reviewed. The property test and numerical analysis were compared, and very similar results were obtained with deviations of maximum tensile strength of 4.75% and fiber direction stress of 5.39%.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.1
• /
• pp.83-90
• /
• 2004

Retaining walls with reinforced earth have been constructed around the world. The use of reinforced earth is a recent development in the design and construction of earth-retaining structure. It is believed that reinforced retaining wall has some advantages which make construction quite simple basically. It wilt take short construction time relatively, comparing, fur example with reinforced-concrete retaining wall. In addition, low price and easy construction will be good attractive points in practical point of view. In this study, five field-tests monitoring data for lateral pressures on geogrid-reinforced retaining wall have been compiled and evaluated. Based on field-tests it is found that horizontal displacements of the facing was measured to be about 0.19∼0.76% and that the maximum tensile strains of reinforcement was evaluated to be about 0.66∼1.98%. The maximum tensile strains, measured from each site, do not reach 5% of the practical allowable strain of the geogrid. And also it is found that the lateral pressure distributions of reinforced-earth retaining wall are close to a trapezoid shape like a flexible retaining wall system, instead of a theoretical triangular shape.