• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.11a
• /
• pp.257-258
• /
• 2023

In this study, it was conducted to improve the physical properties of VAE polymer matrix used as a coating material. A nanocomposite was manufactured using graphene as a reinforcing agent based on a VAE matrix. As a result, improvements in tensile strength, adhesion strength, and porosity were confirmed.

• Journal of the Korean Society for Heat Treatment
• /
• v.7 no.3
• /
• pp.160-168
• /
• 1994

This was studied about mechanical characteristic of AC4A/SiCw 10-30% reinforced composites. Tensile strength of pressed base metal(base metal) with SiCw preform was higher than without pressed base metal(AC4A). If SiCw whisker volume fraction was increased, tensile strength at room temperature was increased. And tensile strength of SiCw 30% was about $35kg/mm^2$. Tensile strength of SiCw 30 % $400^{\circ}C$ at same time aging was the most excellence, about $40kg/mm^2$. The fracture energy value of composite material at three point bending test was higher than AC4A. Dislocation at matrix of composite material was evenly distributed. But dislocation around whisker of composite material was more existed than matrix. The reasom was thought of pile-up around whisker.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2022.04a
• /
• pp.111-112
• /
• 2022

Lightweight aggregate is a porous material that has a lower density than natural aggregate and is a lightweight construction material. Lightweight Aggregate has a suitable purpose because it is effective in reducing the heavy unit mass in high-rise buildings. However, since lightweight aggregate has weak strength and high water absorption compared to natural aggregate, it is difficult to control the quality of concrete. Although lightweight aggregate has disadvantages such as high water absorption, it is expected that the demand for lightweight aggregate concrete will continue to use in the future because the advantage of being able to reduce the weight of concrete is greater. In this study, we conducted an experimantal study on the compressive strength property of cement matrix according to the type of lightweight aggregate.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.12 no.1
• /
• pp.45-49
• /
• 2003

Tensile strength of the woven glass fiber reinforced PET (Poly-Ethylene-Terephthalate) matrix composite manufactured by rapid press consolidation technique was investigated and evaluated. During pre-heating, consolidation and solidification stages, the optimal manufacturing conditions for this composite were discussed based on the void content and tensile properties depending on vacuum condition. It is found that the effect of vacuum condition during preheating gives a substantial difference on the strength as well as microstructure. It is also found that the failure micromechanism shows several energy absorption processes enhancing fracture toughness.

• Structural Monitoring and Maintenance
• /
• v.11 no.3
• /
• pp.219-234
• /
• 2024

The strength reduction factor spectrum is traditionally obtained from a single-degree-of-freedom (SDOF) system with a constant damping coefficient. However, according to the principle of Rayleigh damping, the damping coefficient matrix of a system changes with the stiffness matrix, and the damping coefficient of an equivalent SDOF system changes with the tangent stiffness coefficient. In view of that, this study proposes an equivalent SDOF system with an adaptive damping coefficient and derives a standardized reaction balance equation. By iteratively adjusting the strength reduction factor, the corresponding spectrum with an equivalent ductility factor is obtained. In addition, the ratio between the strength reduction factor that considers adaptive damping and the traditional strength reduction factor, denoted by η, is determined, and the η-μ-T relationship is obtained. Seismic records of Classes C, D, and E sites are selected as excitations. Moreover, a nonlinear response time-history analysis is performed to establish the relationship between the η and T values for the equivalent ductility factor μ. Further, by exploring the effects of the site class, ductility factor, second-order stiffness coefficient, and period T on the mean value of η, a simplified calculation equation of mean η is derived, and η is used as a modified value for the traditional strength reduction factor R spectrum.

• Interaction and multiscale mechanics
• /
• v.1 no.2
• /
• pp.231-250
• /
• 2008

The statistical two-order and two-scale method is developed for predicting the mechanics parameters, such as stiffness and strength of core-shell particle-filled polymer composites. The representation and simulation on meso-configuration of random particle-filled polymers are stated. And the major statistical two-order and two-scale analysis formulation is briefly given. The two-order and two-scale expressions for the strains and stresses of conventionally strength experimental components, including the tensional or compressive column, the twist bar and the bending beam, are developed by means of their classical solutions with orthogonal-anisotropic coefficients. Then a new effective mesh generation algorithm is presented. The mechanics parameters of core-shell particle-filled polymer composites, including the expected stiffness parameters, minimum stiffness parameters, and the expected elasticity limit strength and the minimum elasticity limit strength, are defined by means of the stiffness coefficients and elasticity strength criterions for core, shell and matrix. Finally, the numerical results for predicting both stiffness and elasticity limit strength parameters are compared with the experimental data.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2006.05a
• /
• pp.86-89
• /
• 2006

In this research, the decrease of the tensile strength in CFRP was investigated by experimental and analytical methods. We focused on the role of the interface between the reinforcing fiber and the epoxy resin matrix. The tensile and the interface strengths in CFRF were evaluated using the strand and the short beam specimens. Curtin's model which correlate the mechanical strength of the interface to the tensile strength was introduced for analytical study. The experimental and the analytical results showed good coincidence and we found that the interface strength is the key factor which governs the CFRP's tensile strength.

• Korean Journal of Materials Research
• /
• v.19 no.9
• /
• pp.504-509
• /
• 2009

The Zr-based bulk metallic glass matrix composites of a mixture of gas-atomized metallic glass powders and Fe-based nanostructured powders were fabricated by spark plasma sintering. The Fe-based nanostructured powders adopted for the enhancement of plasticity were well distributed in the matrix after consolidation, and the matrix remains as a fully amorphous phase. The successful consolidation of metallic glass matrix composite with high density was attributed to viscous flow in the supercooled liquid state during spark plasma sintering. Unlike other amorphous matrix composites, in which improved ductility could be obtained at the expense of their strength, the developed composite exhibited improvement both in strength and ductility. The ductility improvement in the composite was considered to be due to the formation of multiple shear bands under the presence of the Fe-based nanostructured particles.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.21 no.3
• /
• pp.76-85
• /
• 2017

In this study, to evaluate the mechanical properties of fiber-reinforced cement composites by strain rate, hydraulic rapid loading test system was developed. And compressive and tensile strength of the hooked steel fiber and polyamide fiber reinforced cement composite were evaluated. As a result, the compressive strength, strain capacity and elastic modulus were increased with increasing strain rate. The effect of compressive strength by type and volume fraction of fibers was not significant. The dynamic increase factor(DIF) of the compressive strength was higher than that of the CEB-FIP model code 2010 and showed a trend similar to that of ACI-349. The tensile strength and strain capacity were increased with increasing strain rate. The hooked steel fibers were drawn from the matrix. The tensile strength and strain capacity of hooked steel fiber reinforced cement composites were increased as the strain rate increased. The tensile strength and deformation capacity of the fiber reinforced cement composites were increased. And, hooked steel fibers were drawn from the matrix. On the other hand, because the bonding properties of polyamide fiber and matrix is large, polyamide fiber was cut-off with out pullout from matrix. The strain rate effect on the tensile properties of polyamide fiber reinforced cement composites was found to be strongly affected by the tensile strength of the fibers.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.1
• /
• pp.122-131
• /
• 1995

The research trends for metal matrix composites have been on basic mechanical properties, fatigue behavior after aging and fractographic observations. In this study, the fatigue crack initiation as well as the fatigue crack growth behavior and the fracture mechanism were investigated through observations of the fracture surface on silicon carbide particles reinforced aluminum metal matrix composites(SiCp/Al). Based on the fractographic study done by scanning electron microscope and replica, crack growth path model and fracture mechanism are presented. The mechanical properties, such as the tensile strength, yield strength and elongation of SiCp/Al composites are improved in a longitudinal direction, however, the fatigue life is shorter than the basic Al6061 alloys. From fractographic observations, it is found that the failure mode is ductile in basic Ai6061 alloys. And because some SiC particles were pulled out from the matrix and a few SiC particles could be seen on the fracture surface of SiCp/Al, crack growth paths are believed to follow the interface of the matrix and its particles.