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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korea Society for Industrial and Applied Mathematics
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The Korean Society for Industrial and Applied Mathematics
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Volume & Issues
Volume 2, Issue 1 - Jun 1996
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A STUDY ON THE HYDROELASTIC RESPONSE OF A PLATE UNDER IMPULSIVE PRESSURES DUE TO BREAKING WAVES
Hang Shoon Choi ; Dong Yeon Lee ;
Journal of the Korea Society for Industrial and Applied Mathematics, volume 2, issue 1, 1996, Pages 1~1
In this paper, breaking waves are generated in a 2-D wave tank and simulated by using a higher-order boundary element method. A piston-type wavemaker is operated by signals composed of elementary waves. The phase of elementary waves is determined by the linear theory such that they are focused to a prescribed position. Calculated plunging waves coincide well with experiment. A steel box with different plate thicknesses is installed at a predetermined position in the tank. Measured impulsive pressures due to breaking waves are found to be 0.8-1.2
corresponds to water density and C to wave celerity. The transverse displacement of the plate is described in terms of modal eigenfunctions. The natural frequencies measured by impact tests in air for thin plate coincide with the computational and theoretical values. The radiationpotential due to plate vibration is derived and the radiation force is expressed in terms of hydroelastic added mass and damping forces. Comparison of natural frequencies of plate in water proves that hydroelastic added mass and damping are properly considered. The measured strain due to regular waves supports the calculated one, but there are apparent discrepancies between theory and experiment in the impulsive case.
COMPUTATIONAL SIMULATIONS OF FLUID FLOWS
Kunio Kuwahara ; Ho Sang Kwak ;
Journal of the Korea Society for Industrial and Applied Mathematics, volume 2, issue 1, 1996, Pages 15~15
A fair portion of the dream to acquire the solutions to the Navier-Stokes equations has come true through the remarkable development of computers and solution algorithms in recent years. However, it is also true that there still remain serious hurdles in simulating general fluid flows. A few numerical trials to overcome the existing difficulties are introduced. The issues in numerical simulations of high-Reynolds-number flows, flows characterized by complex body geometry, and multi-phase flows, are scrutinized. The future of computational fluid dynamics as a promising tool for flow analyses is illuminated by this review.
ON THE TREATMENT OF DUCTILE FRACTURE BY THE LOCAL APPROACH CONCEPT IN CONTINUUM DAMAGE MECHANICS : THEORY AND EXAMPLE
Seoung Jo Kim ; Jin Hee Kim ; Wie Dae Kim ;
Journal of the Korea Society for Industrial and Applied Mathematics, volume 2, issue 1, 1996, Pages 31~31
In this paper, a finite element analysis based on the local approach concept to fracture in the continuum damage mechanics is performed to analyze ductile fracture in two dimensional quasi-static state. First an isotropic damage model based on the generalized concept of effective stress is proposed for structural materials in the context of large deformation. In this model, the stiffness degradation is taken as a measure of damage and so, the fracture phenomenon can be explained as the critical deterioration of stiffness at a material point. The modified Riks'''' continuation technique is used to solve incremental iterative equations. Crack propagation is achieved by removing critically damaged elements. The mesh size sensitivity analysis and the simulation of the well known shearing mode failure in plane strain state are carried out to verify the present formulation. As numerical examples, an edge cracked plate and the specimen with a circular hole under plane stress are taken. Load-displacement curves and successively fractured shapes are shown. From the results, it can be concluded that the proposed model based on the local approach concept in the continuum damage mechanics may be stated as a reasonable tool to explain ductile fracture initiation and crack propagation.
RESONANT MOTION OF A PARTICLE ON AN AXISYMMETRIC CONTAINER SUBJECT TO HORIZONTAL EXCITATION
Yong Kweon Suh ;
Journal of the Korea Society for Industrial and Applied Mathematics, volume 2, issue 1, 1996, Pages 51~51
This study is generalization of the study of Miles[Physica 11D, 1984, pp.309-323]on the resonant motion of a spherical pendulum, which is equivalent to a particle on a spherical container subject to a linear, horizontal excitation. This study covers an arbitrary shape of container and a more general excitation (horizontal but elliptic motion). The averaging method is applied to reduce the governing equations to an autonomous system with cubic nonlinear terms, under the assumption of small amplitude of the container motion. It is shown that both the container shape and the excitation pattern affect the particle dynamics. Under the linear excitation, the anharmonic motion of the particle is possible only for a certain finite range of the parameter a controling the container shape. Stability of the particle''''s harmonic motion is also influenced by the excitation pattern; as the excitation trajectory becomes closer to a circle, the particle''''s motion has a stronger tendency to become stable and to follow the rotational direction of the excitation. Under a circular excitation, the motion is always stable and circular with the same rotational direction as the excitation. Analogy between the present model and that of the surface wave inside a circular is studied quantitatively.