• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.4 s.175
• /
• pp.982-990
• /
• 2000

The finite element alternating method is extended further for general three dimensional cracks in an isotropic body subjected to the mode I loading. The required analytical solution for a dime dimensional crack in an infinite isotropic body is obtained by solving the integral equations. In order to remove the high singularity in integration, the technique suggested by Keat et al. was used. With the proposed method several example problems are solved in order to check the accuracy and efficiency of the method.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.1
• /
• pp.170-180
• /
• 1995

A parallel crack in bonded dissimilar orthotropic planes under out-of-plane loading is analyzed. The problem is formulated by Fourier integral transforms, and reduced to a pair of dual integral equations. By solving the integral equations, the asymptotic stress and displacement fields near the crack tip are determined in closed form, from which the stress intensity factor and energy release rate are obtained. Discontinuity in the stress intensity factor as the distance ratio h/a of the parallel crack approaches zero is found, while the energy releas rate is shown to be continuous at h/a = 0. This information can immediately be used to generate the stress intensity factor for the parallel crack near the interface. By employing "the maximum energy release rate criterion", it could be shown in the case of no existing crack initially that the parallel crack is formed far from the interface for the more compliant material, while it is formed close to the interface for the stiffer material. material.

• Structural Engineering and Mechanics
• /
• v.6 no.6
• /
• pp.711-725
• /
• 1998

Mixed finite element formulations for incompressible materials show pressure oscillations or pressure modes in four-node quadrilateral elements. The criterion for the stability in the pressure solution is the so-called Babu$\check{s}$ka-Brezzi stability condition, and the four-node elements based on mixed variational principles do not appear to satisfy this condition. In this study, a pressure continuity residual based on the pressure discontinuity at element edges proposed by Hughes and Franca is used to study the stabilization of pressure solutions in bilinear displacement-constant pressure four-node quadrilateral elements. Also, a solid mechanics problem is presented by which the stability of mixed elements can be studied. It is shown that the pressure solutions, although stable, are shown to exhibit sensitivity to the stabilization parameters.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.04a
• /
• pp.233-238
• /
• 1999

Localized failure analysis of concrete structures can be carried out effectively by modeling fracture process zone of concrete during crack initiation and propagation. But, the analysis techniques are still insufficient for crack modeling because of difficulties in numerical analysis procedure which describe progressive crack. In this paper, a finite element with embedded displacement discontinuity is introduced to remove the difficulties of remeshing for crack propagation in discrete crack model during progressive failure analysis of concrete structures. The performance of this so-called embedded crack approach for concrete failure analysis is verified by several analysis examples. The analysis results show that the embedded crack approach retains mesh size objectivity and can simulate localized failure under mixed mode loading. It can be concluded that the embedded crack approach cab be an effective alternate to the smeared and discrete crack approaches.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1993.10a
• /
• pp.8-15
• /
• 1993

The transition membrane elements with drilling freedom have been developed. The functionals for the linear problem, in which the drilling rotations are introduced as independent variables, have been presented by Hughes & Bressi. And 4-node membrane elements with drilling degrees of freedom were developed by Ibrahimbegovic. The transition elements can be efficiently used in modelling the in-plane structures, in particular, where the stress concentration exists. A modified Gaussian quadrature adopted to evaluate the stiffness matrices of these transition elements which have slope discontinuity of displacement within the elements. Detailed numerical studies show the excellent performance of the transition elements.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2002.09a
• /
• pp.133-140
• /
• 2002

The purpose of this study is to investigate the seismic behavior of reinforced concrete bridge piers and to provide the data for developing improved seismic design criteria. A computer program, named RCAHEST(Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. In boundary plane at which each member with different thickness is connected. local discontinuity in deformation due to the abrupt change in their stiffness can be taken into account by introducing interface element. The effect of number of load reversals with the same displacement amplitude has been also taken into account to model the reinforcing steel and concrete. The proposed numerical method for the prediction of seismic behavior for reinforced concrete bridge piers is veri fief by comparison with the reliable experimental results.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.1287-1292
• /
• 2010

Recently, many railway stations are built under the railway line in urban area. The passage of railway vehicles generates mechanical vibrations of a wide range of frequency. Thus, it is required to place structural vibration isolation systems to reduce vibration and noise originating from surrounding environments. This study utilizes elastometric bearings as a vibration isolation system. The slab track system on elastometric bearings is called "low vibration track" or "floating slab track." In this low vibration track system, dowel bars or plates can be installed to minimize the discontinuity of displacement between adjacent floating slab tracks. This study is to numerically investigate the effects of dowel members on static behavior of the low vibration track. The study involves two steel dowel systems including dowel bars and dowel plates. Each dowel system is analyzed under the service load condition to assess load transfer efficiency (LTE).

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.11 no.3
• /
• pp.33-38
• /
• 2002

This paper deals with pressure ripple attenuation far separated-type Hydrostatic Transmission (HST) consisting ova variable axial piston pump connected in an open loop to a fried displacement axial piston motor. Pressure ripples in HST is major source of vibration which can lead to fatigue failure of components and cause noise. In order to reduce the pressure ripple, an annular tube tripe hydraulic filter is proposed to attenuate pressure ripples with the high frequencies components to achieve better noise reduction in HST. The basic principle of a hydraulic filter is allied to propagation of pressure wave, reflection, absorption in cross section of discontinuity and resonance in the hydraulic pipeline. It is experimentally shown that the hydraulic filter attenuates about 30∼40dB of pressure ripple with high frequencies. These results will assist in modeling and design of noise reduction in hydraulic control systems, and provide a means of designing a quieter HST.

• Structural Engineering and Mechanics
• /
• v.19 no.6
• /
• pp.749-755
• /
• 2005

In this work, thermo-elastic stability behavior of laminated cross-ply elliptical cylindrical shells subjected to uniform temperature rise is studied employing the finite element approach based on higher-order theory that accounts for the transverse shear and transverse normal deformations, and nonlinear in-plane displacement approximations through the thickness with slope discontinuity at the layer interfaces. The combined influence of higher-order shear deformation, shell geometry and non-circularity on the prebuckling thermal stress distribution and critical temperature parameter of laminated elliptical cylindrical shells is examined.

• Structural Engineering and Mechanics
• /
• v.3 no.1
• /
• pp.75-89
• /
• 1995

A transition membrane element designated as CLM which has variable mid-side nodes with drilling freedoms has been presented in this paper. The functional for the linear problem, in which the drilling rotations are introduced as independent variables, has been formulated. The transition elements with variable side nodes can be efficiently used in the local mesh refinement for the in-plane structures, which have stress concentrations. A modified Gaussian quadrature is needed to be adopted to evaluate the stiffness matrices of these transition elements mainly due to the slope discontinuity of displacement within the elements. Detailed numerical studies show the excellent performance of the new transition elements developed in this study.