• Journal of the Korea Concrete Institute
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• v.23 no.4
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• pp.461-469
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• 2011

In this study, the effect of polyvinyl alcohol (PVA) fiber volume fraction on the pullout behavior of structural synthetic fiber in hybrid structural synthetic fiber and PVA fiber cement composites are presented. Pullout behavior of the hybrid fiber cement composites and structural synthetic fiber were determined by dog-bone bond tests. Test results found that the addition of PVA fiber can effectively enhance the structural synthetic fiber cement based composites pullout behavior, especially in fiber interface toughness. Pullout test results of the structural synthetic fiber showed the interface toughness between structural synthetic fiber and PVA fiber reinforced cement composites increases with the volume fraction of PVA fiber. The microstructural observation confirms the incorporation of PVA fiber can effectively enhance the interface toughness mechanism of structural synthetic fiber and PVA fiber reinforced cement composites.

• Korean Journal of Materials Research
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• v.20 no.3
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• pp.148-154
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• 2010

It is necessary to develop new methods to prevent catastrophic failure of structural material in order to avoid accidents and conserve natural and energy resources. Design of intelligent materials with a self-diagnosing function to prevent fatal fracture of structural materials was achieved by smart composites consisting of carbon fiber tows or carbon powders with a small value of ultimate elongation and glass fiber tows with a large value of ultimate elongation. The changes in electrical resistance of CF-GFRP/GFRP (carbon fiber and glass fiber-reinforced plastics/glass fiber-reinforced plastics) composites increased abruptly with increasing strain, and a tremendous change was seen at the transition point where carbon fiber tows were broken. Therefore, the composites were not to monitor damage from the early stage. On the other hand, the change in electrical resistance of CP-GFRP/GFRP (carbon powder dispersed in glass fiber-reinforced plastics/glass fiber-reinforced plastics) composites increased almost linearly in proportion to strain. CP-GFRP/GFRP composites are superior to CF-GFRP/GFRP composites in terms of their capability to monitor damage by measuring change in electrical resistance from the early stage of damage. However, the former was inferior to the latter as an application because of the difficulties of mass production and high cost. A method based on monitoring damage by measuring changes in the electrical resistance of structural materials is promising for improved reliability of the material.

• Korean Journal of Metals and Materials
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• v.49 no.8
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• pp.589-595
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• 2011

Laminated glass fiber-reinforced plastic (GFRP) composites were applied to an insulating structure of a magnet system for a nuclear fusion device. Decreased inter-laminar strength by a strong repulsive force between coils which is induced a problem of structural integrity in laminated GFRPs. Therefore, it is important to investigate the inter-laminar characteristics of laminated GFRP composites in order to assure more reliable design and better structural integrity. Three types of the laminated GFRP composites using a high voltage insulating materials were fabricated according to each molding process. To evaluate the grade of the fabricated composites, mechanical tests, such as hardness, tensile and compressive tests,were carried out. The autoclave molding composites satisfied almost of the mechanical properties reguested at the G10 class standard, but the vacuum impregnation (VPI) and Prepreg composites did not.

• Structural Engineering and Mechanics
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• v.81 no.6
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• pp.729-736
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• 2022

Earth is facing a serious problem of pollution and scarcity of energy sources. The synthetic fibers used in automobile and Aerospace manufacturing sectors are non-renewable and harmful to environment. International Agency such as FAA and SAE is forcing for green fuel, green materials and structures. Further exploration is much needed to understand its potential in structural applications. In the current study, hemp and Jute fibre based composites were developed and tested for assessing their suitability for possible applications in automobile and aerospace sectors. Composites were undergone tensile test, water absorption test, and fatigue analysis to understand its behavior under various loading conditions. The finite element analysis has been carried out to understand the fatigue behaviour of composites. The results revealed that the usage of hemp and jute fibre reinforced composites can improve mechanical properties and have shown a viable alternative to replace synthetic fibres such as glass fibres for specific applications. Hemp reinforced bio-composites have shown better performance as compared to Jute reinforced bio-composites while water resistance characteristics for hemp is poorer to jute fibres.

• International Journal of Aeronautical and Space Sciences
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• v.11 no.3
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• pp.155-166
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• 2010

I review research on self-sensing and structural optimizations of laminated carbon/epoxy composites in Japan. Self-sensing is one of the multiple functions of composites; i.e., carbon fiber is used as a sensor as well as reinforcement. I present a controversial issue in self-sensing and detail research results. Structural optimization of laminated CFRP composites is indispensable in reducing the weights of modern aerospace structural components. I present a modified efficient global search method using the multi-objective genetic algorithm and fractal branch and bound method. My group has focused its research on these subjects and our research results are presented here.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.441-444
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• 2007

This paper presents a part of micormechanics-based elastic modeling (Lee and Pyo, 2007) of particle-reinforced composites containing slightly weakened interfaces. The Eshelby's tensor for a damaged ellipsoidal inclusion to model particles with slightly weakened interfaces is incorporated into a micormechanical formulation by Ju and Chen (1994). A damage model in accordance with the Weibull's probabilistic function is also developed to simulate the progression of weakened interface in the composites.

• Advances in materials Research
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• v.9 no.4
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• pp.311-321
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• 2020

In this study, Mangifera Indica tree sawdust reinforced bisphenol-A aniline based benzoxazine composites were prepared by varying the sawdust from 20 wt% to 45 wt%. Thermogravimetric analysis of composites revealed excellent compatibility between polybenzoxazine and sawdust from the remarkable growth in char yield from 22% (neat resin) to 36% (for highly filled) and glass transition temperature from 151 to 165℃. Ultimate weight loss of the composites evaluated from the Derivatives of TG plots. Limiting oxygen index values of the composites reported considerable growth i.e.,from 28 to 32 along with the increase in filler content. Differential scanning calorimetry results showed that sawdust particles have an insignificant effect on curing temperature (219℃) for the raise in sawdust content. Structure of the sawdust, benzoxazine monomer, polybenzoxazine and composites were studied using Fourier transformation infrared spectroscopy. Overall, polybenzoxazine composites with sawdust as filler showed improved thermal properties when compared with pure polybenzoxazine.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.46 no.3
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• pp.69-77
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• 2023

Recently, carbon composites have been applied to various fields. However, carbon composites have not been applied to the fishing vessel field due to its structure standards centered on glass composites. In this study, a structural strength evaluation study was conducted for the application of carbon composites in the fishing vessel field. Hull minimum thickness verification test and hull joint verification test were conducted. Compared to glass composites, the verification was based on equivalent or better performance. The results show that carbon composites can reduce the weight by 20% compared to glass composites. For hull joints, it was necessary to increase the thickness of the joint seam by the thickness of the hull to apply carbon composite. Through this study, a standard for the application of carbon composites to fishing vessel can be established.

• Journal of Korean Association for Spatial Structures
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• v.3 no.3 s.9
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• pp.85-93
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• 2003

Steel, concrete and their combination materials are the most 6commonly used materials for civil engineering structural systems such as buildings, bridge structures and other structures. Recently, however, fiber reinforced polymer (FRP) composites, a relatively new composite material made of fibers and polymer resins, have been gradually used in structural systems as an alternative structural material. This paper describes a comparison of design strength equations for steel column and FRP composite column based on design philosophies. The safety factors used in allowable stress design (ASD) are relatively higher in FRP structural design than steel structural design. Column critical stress equations of FRP composites column from an experimental study can be represented by Euler elastic buckling equation at the long-range of slenderness, and an exponential form at the short-range of slenderness as defined in Load and Resistance Factor Design (LRFD) of steel column. The column strength of steel and FRP composite columns in large slenderness is independent of material strength, this result verified the elastic buckling equation as derived by Eq. (15) and Eq. (5).

• International Journal of High-Rise Buildings
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• v.12 no.2
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• pp.145-152
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• 2023

Typical floor systems in contemporary tall buildings consist of reinforced concrete or composite metal deck over framing members and account for a majority of the structural weight of the building. The use of high-density materials, such as reinforced concrete and steel, increases the weight of floor systems, reducing the system's overall efficiency. With the introduction of high-performance materials, mainly mass timber products, and fiber-reinforced composites, in the construction industry, designers and engineers have multiple options to choose from when selecting structural materials. This paper discusses the application of mass timber and carbon fiber composites as structural materials in floor systems of tall buildings. The research focused on a comparative analysis of the structural system efficiency for five different design options for tall building floor systems. Finite Element Analysis (FEA) method was adopted to develop a simulation framework, and parametric structural models were simulated to evaluate the structural performance under specific loading conditions. Simulation results revealed the advantages of lightweight structural materials to improve system efficiency and reduce material consumption. The impact of mechanical properties of materials, loading conditions, and issues related to fire engineering and construction were briefly discussed, and future research topics were identified in conclusion.