• Journal of the Korean Ceramic Society
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• v.28 no.10
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• pp.810-818
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• 1991

Fracture responses of Al2O3 tubes were investigated for various loading paths under combined tension/torsion. The fracture criterion did not depend on loading paths. Fracture angles agreed well with the maximum tensile stress criterion. As the loading condition approaches a shear dominant state, the tensile principal stress at fracture increases compared to the uniaxial fracture strength. By using the Weibull modulus obtained from tension and torsion tests, the Weibull statistical fracture strengths were compared with experimental data. This comparison suggests that fracture may occur at the surface of the specimen when tensile stress is dominant, but within the volume of the specimen when shear stress is dominant. The Weibull fracture strength increased as the loading conition approached a shear dominant state, but underestimated compared to experimental data. Finally, a new fracture criterion was proposed by including the effect of compressive principal stress. The proposed criterion agreed well with experimental data of Al2O3 tubes not only at combined tension/torsion but also at balanced biaxial tension.

• Journal of Korean Association for Spatial Structures
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• v.20 no.3
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• pp.91-98
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• 2020

For form stability of membrane structures, membrane material is required to be in tension. Therefore, in planning and maintenance management, the engineer should consider enough about introduction of stress during construction and re-introduction of stress after completion. Clamping part is an important portion with the function for introducing tension into membrane materials, and the function to transmit stress to boundary structures, such as steel frames. Then, the purpose of this research is to clarify stress condition and stress transfer mechanism including clamping part of membrane structures, and to grasp the changing tendency of membrane structures with the passage of time. In this research, following previous one, we perform well-balanced evaluation by conducting tensile fractured tests of clamping part's specimens, and by measuring individually the amount of displacement of not only overall specimen's length but membrane material and clamping part. Thereby, we consider the influence the difference in the hardness of edge rope and the difference in the direction of thread affect modification and fracture load.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.186-191
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• 2001

Tensile residual stress happen by difference of coefficients of thermal expansion between fiber and matrix is one of the serious problems in metal matrix composite(MMC). In this study, TiNi alloy fiber was used to solve the problem of the tensile residual stress as the reinforced material. TiNi alloy fiber improves the tensile strength of composite by occurring compressive residual stress in matrix using shape memory effect of it. Pre-strain was added to generate compressive residual stress inside TiNi/A16061 shape memory alloy(SMA) composite. It was also evaluated the effect of compressive residual stress corresponding to pre-strains variation and volume fraction of TiNi alloy. AE technique was used to clarify the microscopic damage behavior at high temperature and the effect of pre-strain difference of TiNi/A16061 SMA composite. In addition, two dimensional AE source location technique was applied to inspect the crack initiation and propagation in composite.

• Magazine of the Korea Concrete Institute
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• v.6 no.4
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• pp.102-112
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• 1994

The drying shrinkage of concrete has a close relation to the water movement. Since the diffusion process of water in concrete is strongly dependent on the temperature and the pore humidity, the process is highly nonlinear phenomena. This study consists of two parts. The first is the development of a finite element program which is capable of simulating the rnoisture distri- ,bution in concrete, and the other is the estimation of the differential drying shrinkage and stress considering creep by using the modified elastic modulus due to inner temperature change and maturity. It is shown that the analytical results of this study are in good agreement with experlimental data in the literatures, and results calculated by BP-KX model. The internal stress caused by moisture distribution which was resulted from the diffusion process, was calculated :quantitatively. The tensile stress which occured in the drying outer zone mostly exceeded the tensile strength of concrete, and necessarily would result in crack formation.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4481-4490
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• 2022

In this study, a new rupture disk corrosion test (RDCT) method was developed for real-time detection of stress corrosion cracking (SCC) initiation of Alloy 600 in a primary water environment of pressurized water reactors. In the RDCT method, one side of a disk specimen was exposed to a simulated primary water at high temperature and pressure while the other side was maintained at ambient pressure, inducing a dome-shaped deformation and tensile stress on the specimen. When SCC occurs in the primary water environment, it leads to the specimen rupture or water leakage through the specimen, which can be detected in real-time using a pressure gauge. The tensile stress applied to the disk specimen was calculated using a finite element analysis. The tensile stress was calculated to increase as the specimen thickness decreased. The SCC initiation time of the specimen was evaluated by the RDCT method, from which result it was found that the crack initiation time decreased with the decrease of specimen thickness owing to the increase of applied stress. After the SCC initiation test, many cracks were observed on the specimen surface in an intergranular fracture mode, which is a typical characteristic of SCC in the primary water environment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.5
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• pp.1543-1551
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• 1996

The static tensile load bearing capability of as adhesively-bonded tubular single lap jint that is calculated usign the linear mechanical properties of adhesive is usually far from the experimentally determined because the majority of the load transfer of the adhesively-bonded jointd is accomplished by the nonlinear behavior of the rubber-toughened eoxy adhesive. In this paper, both the nonlinear mechanical properties and the fabrication residual thermal stresses of adhesive were included in the calculation of the stresses of adhesively-bonded joints. The onlinear tensile properties of adhesive were approximated by an exponential form which was represented by the initial tensile modulus and ultimate tensile stength of adhesive. The stress distribution in the adhesive were calculated by applying the load obtained from the tensile tests. From the tensile tests and the stress analysis of adhesively-bonded hoints, the failure model for adhesively-bonded tubular single lap joints was proposed.

• Tunnel and Underground Space
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• v.23 no.5
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• pp.362-371
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• 2013

We conducted hollow cylinder tensile strength tests and Brazilian tests in Seokmo granite to measure tensile strength necessary for estimating the magnitude of the maximum horizontal principal stress in hydraulic fracturing stress measurements. Two different pressurization rates were used in hollow cylinder tests. Tensile strengths were determined to be higher at higher pressurization rate, which suggests that tensile strength should be measurement at the same rate used in actual in situ hydraulic fracturing tests. Considering the effect of pressurization rate and specimen size on tensile strength, the hollow cylinder tests and Brazilian tests yield similar results each other. This demonstrates that Brazilian tests can be utilized to produce representative tensile strengths for interpretation of hydraulic fracturing test results.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1994.04a
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• pp.155-162
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• 1994

The drying shrinkage of concrete has a close relation to the water movement, Since the diffusion process of water in concrete is strongly dependent on the temperature and pore humidity, the process is highly nonlinear phenomena. It is shown that the analytical results of this study are in good agreement with experimental data in the literatures, and results calculated by BP-KX model. The internal stress caused by moisture distribution which was resulted from the diffusion process, was calculated quantitatively. The tensile stress which occurred in the drying outer zone mostly exceeded the tensile strength of concrete, and necessarily would result in crack formation.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.379-385
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• 2003

In the existing method to design geosynthetic reinforced embankment, the required strength of reinforcements is determined by vertical stress only rather than strain. This strength is not in accord with tensile strength that behaves as reinforcement in earth structures. The reinforcement and adjacent soil on the failure plan behave in one unit at the initial stress phase but they make a gap in strain as stress increases. This issue may cause a big impact as a critical factor on geosynthetic reinforcement design in earth structures. The quantitative analysis on strain behavior was performed with a PET Mat reinforced embankment on soft ground. From this study, several outstanding discussions are found that tensile strength of reinforcement governs the failure of embankment when the soil stress is greater than failure stress. Also the optimum required tensile strength of geosynthetic reinforcement(Tos) should be determined by stress, displacement, displacement gap and safety factor of soil-PET Mat at the location of PET Mat.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.4
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• pp.130-136
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• 2018

In this paper, the effects of different 3D printing parameters including laminated angle and annealing temperature, were observed for their effects on tensile testing. In 3D printing, a filament is heated quickly, extruded, and then cooled rapidly. Because plastic is a poor heat conductor, it heats and cools unevenly causing the rapid heating and cooling to create internal stress within the printed part. Therefore, internal stress can be removed using annealing and to increase tensile strength and strain. During air cooling at annealing temperature $140^{\circ}C$, the strain of laminated angle $45^{\circ}$ specimens tended to increase by 46% while the tensile stress tended to increase by 7.4%. During oven cooling at annealing temperature $140^{\circ}C$, the strain of laminated angle $45^{\circ}$ specimens tended to increase by 34% while the tensile stress tended to increase by 22.2%. In this study, we found "3D printing with annealing" eliminates internal stress and increases the strength and stiffness of a printed piece. On the microstructural level, annealing reforms the crystalline structures to even out the areas of high and low stress, which created fewer weak areas. These results are very useful for making 3D printed products with a mechanical strength that is suitable for applications.