• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.277-280
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• 2006

This paper deals with the shear deformation charateristics of concrete beams strengthened with steel/FRP Bar. Applying the shear behavioral model based on shear deformation compatibility to RC beams tested by Ahmed K. El-Sayed et al.(2006), their transverse deformation in the web are calculated at ultimated loads after decoupling the shear carried by arch action in each beams. The calculated transverse deformation at ultimated loads are nearly same for the different reinforcement ratio. From these results, the temporary transverse deformation limit criterion is deduced. Using the proposed temporary limit criterion, the shear strength of concrete beams strengthen with FRP Bar tested by Ahmed K. El-Sayed et al.(2006) is predicted. These predicted values are compared with the measured values and the results are also compared with the current ACI and JSCE equation. The proposed method predicts the ultimate shear capacities more accurately than the equation of ACI and JSCE code. The predictions by the ACI and JSCE code are founded to be very conservative.

• Transactions of Materials Processing
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• v.13 no.7
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• pp.629-634
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• 2004

Based on plastic instability, analytical prediction of bursting failure on tube hydroforming processes under combined infernal pressure and independent axial feeding is carried out. Bursting is irrecoverable phenomenon due to local instability under excessive tensile stresses. In order to predict the bursting failure, three different classical necking criteria such as diffuse necking criterion for sheet and tube, local necking criterion for sheet are introduced. The incremental theory of plasticity for anisotropic material is adopted and then the hydroforming limit and bursting failure diagram with respect to axial feeding and hydraulic pressure are presented. In addition, the influences of the material properties such as anisotropy Parameter, strain hardening exponent and strength coefficient on bursting Pressure are investigated. As results of the above approach, the hydroforming limit in view of bursting failure is verified with experimental results.

• Structural Engineering and Mechanics
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• v.11 no.5
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• pp.519-534
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• 2001

The effect of the initial imperfections on the nonlinear behaviors and ultimate strength of the thin-walled members subjected to the axial loads, obtained by the finite element stability analysis, are examined. As the initial imperfections, the bucking mode shapes of the members are adopted. The buckling mode shapes of the thin-walled members are obtained by the transfer matrix method. In the finite element stability analysis, isoparametric degenerated shell element is used, and the geometrical and material nonlinearity are considered based on the Green Lagrange strain definition and the Prandtl-Reuss stress-strain relation following the von Mises yield criterion. The U-, box- and I-section members subjected to the axial loads are adopted for numerical examples, and the effects of the initial imperfections on the nonlinear behaviors and ultimate strength of the members are examined.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.17-21
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• 2002

A finite element method based on the two-dimensional progressive failure analysis is presented for characterizing the strength and failure of the unidirectional-fabric hybrid laminated composite joints under pin loading. The 8-node laminated shell element is incorporated in the updated Lagrangian formulation. Various failure criteria including the maximum stress, Tsai-Wu, Yamada-Sun, and combinations of them are used in conjunction with the complete unloading stiffness degradation method. For the verification, joint tests are conducted for the specimens with various geometries. Although there are some differences depending on the geometry, the finite element model using the Yamada-Sun or the combined Yamada-Sun and Tsai-Wu criterion predicts the failure strength best.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.6
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• pp.16-20
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• 2010

This study proposes a structural design method for the upper control arm installed at the rear side of a SUV. The weight of control arm can be reduced by applying the design. In this research, the former includes optimization technology, and the latter the technologies for selecting aluminum as a steel-substitute material. Strength assessment is the most important design criterion in the structural design of a control arm. At the proto design stage of a new control arm, FE (finite element) analysis is often utilized to predict its strength. In this study, the kriging interpolation method is adopted to obtain the minimum weight satisfying the strength constraint and durability criteria. The optimum results determined from the in-house program are compared with those of ANSYS WORKBENCH. The durability assessment is obtained by a index of fatigue durability and trial & error method, MSC. Fatigue program.

• 전기의세계
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• v.30 no.3
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• pp.172-176
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• 1981

The reduction in the breakdown field strength due to electrode surface roughness was calculated by applying the streamer breakdown criterion and the surface roughness factor, and measurements of static breakdown voltage for a gap with an artificial protrusion were made under the uniform field at pressures up to 4 bar in pressurized $SF_{6}$. The effect of polarity of highly stressed electrode on the breakdown field strength was also investigated. The measurements have shown that the measured breakdown levels for a protrusion located on the cathode agree with those calculated and the values measured with an identical anode protrusion are substantially higher and more scattered. This may be explained if it assumed that a high rate of production of initiatory electrons is maintained at the tip of a cathode protrusion by field emission. In practical point of view, the breakdown levels in pressurized $SF_{6}$ can be bereliably estimated from the values calculated.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.73-77
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• 2004

Failure predictions of composite single-lap bonded joints were performed considering both of composite adherend failure and bondline failure. An elastic-perfectly plastic model of adhesive and a delamination failure criterion are used. The failure prediction results such as failure mode and strength have very good agreements with the test results of joint specimens with various bonding methods and parameters. The influence of variations in the effective strength (that is, adhesion performance) and plastic behavior of adhesive on the failure characteristics of composite bonded joints are investigated numerically. The numerical results show that optimal joint strength is archived when adhesive and delamination failure occur in the same time.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.195-198
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• 2000

Recently, the anriwashout underwater concrete has been increasingly used for underwater structures such as vary high diaphrame walls of high strength massive concrete structures. In this study, experiments were made on the fundamental properties of antiwashout underwater concrete replaced with Fly Ash from 10% to 30% to improve its properties. Resultant to the test, we got the results as follows; the value of slump flow wasi ncreased, the setting, time was very delayed, and the heat evolution amount decreased, whereas the amount of suspended solids became high, and pH value became low as to increasing the replacement ratio of Fly Ash. Also the ratios of compressive strength (in water compared to in air) at 28day were obtained over 90%, and these values were satisfied with 70% of a criterion.

• Computers and Concrete
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• v.20 no.1
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• pp.85-97
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• 2017

With a special attention to the different stages of a typical loading path travelled in a fluid confined concrete test, this paper introduces a physically consistent model for the stress-strain curve of actively confined normal-strength concrete in the axial direction. The model comprises of the five elements of: (1) a criterion for the peak or failure strength, (2) an equation for the peak strain, (3) a backbone hydrostatic curve, (4) a transient hardening curve linking the point of departure from the hydrostatic curve to the failure point, and finally (5) a set of formulas for the post-peak region. Alongside, relevant details and shortcomings of existing models will be discussed in each part. Finally, the accuracy and efficiency of the proposed model have been verified in a set of simulations which compare well with the experimental results from the literature.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.4
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• pp.54-60
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• 2009

Weight reduction of automobile parts has been sought to achieve fuel efficiency and energy conservation. In this study, a shape design procedure is suggested to obtained the lightweight design of an outer tie rod. The developed aluminium Al6082M is selected as a steel-substitute material. Strength assesment and durability are the important design criterion in the structural design of an outer tie rod. This study considers strength and durability in the optimization process. In this study, the kriging interpolation method and trial and error method are adopted to obtain the minimum weight satisfying the strength and durability constraints.