• Composites Research
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• v.13 no.4
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• pp.67-74
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• 2000

The general solution of the anti-plane shear problem for the curved interfacial crack between viscoelastic foam and composites was investigated with the complex variable displacement function. Kelvin-Maxwell three parameter model is used to present viscoelasticity and the Laplace transform was applied to treat the viscoelastic characteristics of foam in the analysis. The stress intensity factor near the interfacial crack tip was predicted by considering both anisotropic and viscoelastic properties of two different materials. The results showed that the stress intensity factor increased with increasing the curvature of the curved interfacial crack and it also increased and eventually converged to a specific value with increasing time. The stress intensity factor increased with increasing the ratio of stiffness coefficients between foam and composites and the effect of fiber orientation on the stress intensity factor decreased with increasing the ratio of stiffness coefficients between foam and composites.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1A
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• pp.1-13
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• 2008

The web of a horizontally curved plate girder bridge is, in general, subject to not only longitudinal flexural in-plane stress but also out-of-plane bending stress. Therefore, the induced stresses in the fillet welded joints at the intersection of the web and flange plates in the curved plate girder bridge can be considerably high, and the welded joints of gusset plates connecting the main girder to the floor beams or sway bracings can be subject to much more severe situation than those in the ordinary straight plate girder bridge. In order to investigate the cause of fatigue crack occurred in a curved girder bridge that has been served in about 23 years, in this study, field load tests have been performed to obtain the stress characteristics at the welded joint under the real traffic flow. Using the test results, we have investigated the causes of the occurrence of various fatigue cracks and have estimated the fatigue lives for the cracks. In addition, the characteristics of structural behavior at welded joint of the curved girder bridge have been examined by comparing the FE analysis and the field test result.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.12
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• pp.1441-1446
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• 2014

In the present paper, the effects of the thickness and width of a curved wide-plate, the crack length, and the strain hardening exponent on the crack-tip constraint of the curved wide-plate were investigated. To accomplish this, detailed three-dimensional elastic-plastic finite element (FE) analyses were performed considering various geometric and material variables. The material was characterized by the Ramberg-Osgood relationship, and the Q-stress was employed as a crack-tip constraint parameter. Based on the present FE results, the variations in the Q-stress of the curved wide-plate with the geometric variables and material properties were evaluated. This revealed that the effect of out-of-plane constraint conditions on the crack-tip constraint was closely related to the in-plane constraint conditions, and out-of-plane constraint conditions affected the crack-tip constraint more than in-plane constraint conditions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.6
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• pp.969-980
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• 2003

The interactions between curved cracks are examined in an orthotropic plate and the effects of rectilinear anisotropy on the stress intensity factors are analyzed. The finite element alternating method (FEAM) is used in this study to get the stress intensity factors for the multiple curved cracks. To obtain analytical solutions, which is necessary in FEAM, the curved cracks are modeled as continuous distributions of dislocations, and integral equations are formulated for unknown dislocation density functions to satisfy the given resultant forces on the crack surfaces. Several basic problems are solved to verify the accuracy and efficiency of the proposed method and it can be found that present results show good agreements with the previously published results.

• Computers and Concrete
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• v.31 no.1
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• pp.9-21
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• 2023

The published studies usually used analytical method, numerical methods or experimental method to determine the stress-strain state and displacement of the single-layer or multi-layer curved shell types, but with a small scale model. However, a full scale multi-layer doubly curved concrete shell roof model should be researched. This paper presents the results of the experiment and simulation analysis involving stress-strain state, sliding between layers, the formation and development of the full scale double-layer doubly curved concrete shell roof when this shell begins to crack. The results of the this study have constructed the load-sliding strain relationship; strain diagram; stress diagram in the shell layers; the N_x, N_y membrane force diagram and deflection of shell. Thisresults by experimental method on a full scale model of concrete have clarified the working of multi-layer doubly curved concrete shell roof. The experimental and simulation results are compared with each other and compared with the Sap2000 software.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.8
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• pp.794-800
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• 2015

This paper describes the design for a defective product inspection device for the curved glass used in smart-phone. Cameras are used as inspection devices to find cracks in LCDs (Liquid Crystal Displays), PDPs (Plasma Display Panels), etc. The devices used to inspect the curved glass used in smart-phone consist of a camera, two back-light apparatus, an inspection apparatus main body, and an image processing program. Camera image calibration was performed to smooth an image taken with the camera, and as a result, the average error was less than 0.12 pixels. And the image of a smart-phone's curved glass taken with the camera was processed using the produced program. As a result, the program could correctly extract the cracks on the curved glass. Thus, it is thought that the designed inspection device can successful detect cracks in curved tempered glass.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.1
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• pp.47-55
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• 2008

Recently, it has been reported that buried pipes' crack is concentrated on curved parts. In this study, 3D-Finite element analysis is performed for Analytical Evaluation on the Structural Safety of Horizontally Curved Parts of Buried Pipe. The constructed pipe cracked in curved parts of pipe is analyzed and all kinds of loads affected to buried pipes are considered. Displacement, stresses and buckling analysis are performed. The stress analysis shows that stress in curved parts is larger than stresses in straight parts and exceeds allowable stress in some parts. So, stress analysis on curved parts is needed for safety for buried pipe.

• International Journal of Precision Engineering and Manufacturing
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• v.2 no.3
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• pp.11-18
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• 2001

A simple and convenient method of analysis for obtaining the individual stress intensity factors in a three-dimensional mixed mode crack is proposed. The procedures presented here are based on the path independence of J integral and mutual or two-state conservation integral, which involves two elastic fields. The problem is reduced to the determination of mixed mode stress intensity factor solutions in terms of conservation integrals involving known auxiliary solutions. Some numerical examples are presented to investigate the effectiveness and applicability of the method for a three-dimensional penny-shaped crack problem under mixed mode. This procedure is applicable to a three-dimensional mixed mode curved crack.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.4
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• pp.363-368
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• 2016

In this study, we numerically analyze fatigue cracks of curved pipes under cyclic loadings. Numerical models of the curved pipes are developed. The models are verified with the experimental results in terms of fatigue lives and development process of the fatigue cracks. Erosion technique is applied to the solid elements in order to describe shapes of the fatigue cracks and estimate the fatigue lives. Also, development of the fatigue cracks is described by allocating sufficient number of solid elements in the radial direction. Fatigue lives and shapes of the crack resulting from numerical analyses show good agreement with those of the experiment considering ${\pm}100mm$ displacement. In addition, estimation of the fatigue life caused by displacement with different magnitude is conducted. We expect that the model can be applied to understand the relation between fatigue lives and characteristics of pipes or loadings.

• Geotechnical Engineering
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• v.14 no.3
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• pp.109-122
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• 1998

In the design and construction of Keystone block reinforced wall with geogrid, previous on the behaviour of wall in curved area is required. This study is to investigate the structural stability of wall and problems during construction in curved area. Previous analyzing methods, usually used for straight area of wall, have been reviewed to find any problems in applying to stability analysis of curved area. Thus, the purpose of this study is to show how to analyse the straight area of Keystone block wall first, and then turn this to use for analyzing various significance, concerning the design or construction of curved high keystone block wall. and the stress behavior on retaining wall between straight and curved conditions by F.E.M, using the shell analysis theory.