• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.117-118
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• 2006

The objective of this paper is to investigate into bending and failure characteristics of ISB panel with dimple shapes as inner structures. Through three-points bending test, the force-displacement curve and the failure shape are obtained to examine the deformation pattern, characteristic data including maximum load and displacement at the maximum load and failure pattern for the ISB panel. In addition, the influence of design parameters for ISB panel on the bending stiffness and failure mode has been found. From the results of the experiments, it has been shown that bending and failure characteristics of the ISB panel can be controlled by the ratio of radius and the direction of the material.

• Journal of Welding and Joining
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• v.29 no.6
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• pp.49-55
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• 2011

With the development of pre-painted steel sheets for automotive body application, a new joining method is required such as hybrid joining with combination of adhesive bonding and mechanical joining. The objective of this study is to investigate the effect of pre- and post-baking of adhesive bonding on failure mode and strength of hybrid joining of automotive steel sheets. Experiments show that the hybrid joining exhibits better bonding strength and displacement than conventional adhesive joining and mechanical fastening each. Comparison of pre- and post-baked hybrid joining results suggested that baking at $160^{\circ}C$ after mechanical joining was found to have higher joining properties than pre-baking condition. The prebaking condition changed its fracture mode from interfacial to button fracture. The changes in fracture mode with post-baking of hybrid joining was attributed to variation in neck thickness and undercut of joint.

• Journal of the Korea Concrete Institute
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• v.28 no.2
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• pp.141-148
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• 2016

This paper employed finite element method (FEM) to study the dynamic response of Steel Fiber-Reinforced Concrete(SFRC) panels subjected to impact loading by spherical projectiles. The material properties and non-linear stress-strain curves of SFRC were obtained by compression test and flexural test. Various parametric studies, such as the effect of fiber volume fraction and thickness of panels, are made and numerical analyses are compared with experiments conducted. It is shown that protective performance of concrete panels will be improved by adding steel fiber. Area loss rates and weight loss rates are decreased with increasing fiber volume fraction. Also, penetration modes can be expected by FEM, showing well agreement with experiment. Results can be applied for designing the protection of military structures and other facilities against high-velocity projectiles.

• Journal of the Korean Geosynthetics Society
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• v.9 no.4
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• pp.17-25
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• 2010

Evaluation of stability in traditional designing of reinforced soil structures is executed by examination of internal and external stability. Analysis of internal stability is for pull-out and ductile strength. Analysis of external stability is for settlement, overturning and sliding. To minimize inherent uncertainties of soil properties and analytical model, reliability analysis was developed recently. In this study, reliability analysis method considering simultaneous failure probability for various failure mode of internal and external stability is proposed. By applying uni-modal bounds, Stability of system reliability of reinforced soil structures is evaluated by integrating multi failure mode for various analytical model. Because of complex consideration for various failure shapes and modes, it is possible to secure advanced safety by using simultaneous failure probability. And evaluation of reinforced soil structure is executed by representative index, simultaneous failure probability, than previous method.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.286-291
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• 2001

Most cracks in the structure occur under mixed mode loadings and those propagation depend on the stress ratio very much. So, it is necessary to study the fatigue behavior under mixed mode loading as stress ratio changes. In this paper, fatigue crack propagation behavior was investigated respectively at stress ratio 0.1, 0.3, 0.5, 0.7 and we change loading application angle to $0^{\circ},\;30^{\circ},\;60^{\circ}$ to apply various loading. mode. The mode I and II stress intensity factors of CTS specimen used in this study were calculated by displacement extrapolation method using FEM(ABAQUS). Using both the study through the experiment and the theoretical study through FEM analysis, we studied the relation between crack propagation rate and stress intensity factor range at each loading mode due to the variation of stress ratio. Also, when the crack propagated under given stress condition and given loading mode condition, we studied what the dominant factors of the crack propagation rate were at each case.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.43-44
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• 2006

Generally almost all fatigue crack growth is affected by model. For this reason a study on model has concentrated in the field of fracture mechanics. However the fatigue crack initiation and growth in machines and structures usually occur in mixed mode loading. If there is any relationship between the cause of fracture in mixed mode loading and fracture surface, fracture surface pattern will be the main mean explaining reasons of fatigue fracture and obtaining further information about fracture process. In this paper four point shear-fatigue test with Aluminum alloy Al 5083-O is carried out from this prospect and then the mixed mode distribution of fracture surface is examined from the result after identifying the generation of fatigue crack surface pattern. It was found from the experimental results that the fatigue crack surface pattern and the fatigue crack shear direction are remarkably consistent. Furthermore It is possible that the analysis of distribution of mixed mode through the fatigue crack surface pattern.

• Journal of Korean Society of Steel Construction
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• v.26 no.2
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• pp.69-79
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• 2014

This paper presents the experimental results of flexural behavior of steel beam strengthened with fiber reinforced polymer plastic (FRP) strips subjected to static bending loading. Four H beams were fabricated strengthened with aramid strips and carbon strips and one control specimen were also fabricated. Among them two specimens were strengthened with partial length. The H-beams had two types of failure mode, depending on the length of the FRP strips:(1) strip debonding in beams with partial length reinforcement and (2) strip rupture in beams with full length reinforcement. From the test, it was observed that maximum increase of 16% was also achieved in bending-load capacity.

• Journal of the Korean Institute of Gas
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• v.7 no.2 s.19
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• pp.1-6
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• 2003

In this work, procedure evaluating failure modes such as pipe rupture, large scale leak, and small scale leak was suggested using equations to assess remaining strength by corrosion failure. Additionally, the method to predict probability of failure was suggested according to the aforementioned failure modes, and by combining data on corrosion rate, probability of long-term failure can be induced. This work will be very useful in predicting lifetime or exchanging period of pipeline.

• Journal of the Korea Concrete Institute
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• v.19 no.2
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• pp.145-151
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• 2007

The shear failure modes of FRP strengthened concrete beams are quite different to those of the beams strengthened with steel stirrups. When the beams are externally wrapped with FRP composites, many beams fail in shear due to concrete crushing before the FRP reaches its rupture strain. In order to predict the shear strength of such beams, the effective strain of the FRP must be blown. This paper presents the results of an experimental study on the performance of reinforced concrete beams externally wrapped with FRP composites and infernally reinforced with steel stirrups. The main parameters of the tests were FRP reinforcement ratio, the type of fiber material (carbon or glass) and configuration (continues sheets or strips). The experimentally observed effective strain of the FRP was compared with the strain calculated using a proposed method.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.7
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• pp.51-59
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• 2004

An experimental procedure to identify failure modes of impact damage using sensor signals and to analyze their general features is examined. A series of low-velocity impact tests from low energy to damage-induced high energy were performed on the instrumented drop weight impact tester to monitor the stress wave signals due to failure modes such as matrix cracking, delamination, and fiber breakage. The wavelet transform(WT) and Short Time Fourier Transform(STFT) are used to decompose the piezoelectric sensor signals in this study. The extent of the damage in each case was examined by means of a conventional ultrasonic C-scan. The PVDF sensor signals are shown to carry important information regarding the nature of the impact process that can be extracted from the careful signal processing and analysis.