Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of Ocean Engineering and Technology
Journal Basic Information
Journal DOI :
Korean Society of Ocean Engineers
Editor in Chief :
Volume & Issues
Volume 7, Issue 2 - Dec 1993
Volume 7, Issue 1 - Jun 1993
Selecting the target year
Study of Nonlinear Wave Diffraction Using the 2-Dimensional Numerical Wave Tank
Journal of Ocean Engineering and Technology, volume 7, issue 2, 1993, Pages 9~18
Numerical wave tank is a robust tool by which the nonlinear interactions between the body and the free-surface can be treated in time-domain. In this paper, a two-dimensional numerical wave tank based on the Spectral/Boundary-Element Method is developed, and applied successfully to the study of nonlinear wave diffraction around a submerged circular cylinder. Particularly, it is shown that the high-order wave components of significant wave height are developed in the lee-side of the cylinder and that these waves result in a negative drift force on the circular cylider.
Static Tensile Strength Evaluation of Notched Coeposite Materials
Journal of Ocean Engineering and Technology, volume 7, issue 2, 1993, Pages 19~29
The static tensile tests of GFRP, ID300, CFRID300 and CFRPEEK were made on the plain and notched specimens at room temperature. The results were discussed based on linear notch mechanics which was proposed by H.Nistani. The fracture of notched GFRP, ID300, CFRID300 and CFRPEEK specimens is controlled by the elastic maximum stress,
, and the notch root racius,
, alone, independently of the other geometrical conditions. The relation between fracture nominal stress,
, and stress concentration factor,
and a part where
is nearly constant independent of
. A similar phenomenon can be seen in the fatigue tests of notched specimes under rotating bending or push-pull. The almost constant
values correspond to the nearly constant apparent stress intensity factor,
values, obtained by assuming ,
=0. This can be attributed to the existence of the stable crack. Linear notch mechanics is very useful for analyzing the static tensile fracture behavior of notched GFRP, ID300, CFRPEEK specimens.
Computation of Flow around Single Rectangular Cylinders with a Splitter Plate
Journal of Ocean Engineering and Technology, volume 7, issue 2, 1993, Pages 30~36
Incompressible, unsteady flow around various single rectangular cylinders of side ratios ranging from 0.005 to 2.0 immersed in uniform flow is computed by the vortex tracing me thod. Results with and without a splitter plate pttached to the rear center of the cylinder are compared. The objective of this study is to investigate predictability of the effects of the splitter plate on drag by the method. Without the splitter plate, computed drag coefficients for cylinders of large side ratios are in good agreement with measured values, but are over predicted for those of small side ratios. With the splitter plate, drag coefficient is reduced significantly due to suppression of vortex growing near the base and interaction between the separated shear layers.
Development and application of impact vibration absorber
Journal of Ocean Engineering and Technology, volume 7, issue 2, 1993, Pages 37~43
The simplest vibrtion absorber is the impact damper which consists of a small mass allowed to impact between two gaps sp that energy is dissipated by conversion into noise and heat. Impact damping is a passive vibration control technique to attenuate the vibrations of lightly damped. It has been investigated to reduce the excessive vibrations of turbin blades, radar antennas, machine tools and tall light poles. In this paper, the efficiency of impact vibration absorber was investigated. A steady state vibration of two equispaced impacts per cycle was assumed. The analysis based on the assumption has been considered and the theory is examined experimentally.
Impact Response Behaviors of Laminated Composite Plates Subjected to the Transversely Impact of a Steel Ball
Journal of Ocean Engineering and Technology, volume 7, issue 2, 1993, Pages 44~56
The purpose of this paper is to analyze the impact response behaviors of glass/epoxy laminated composite plates subjected to the transversely impact of a steel ball. For this purpose, dynamic finite element analysis based on the higher-order shear defomation plate theory is used to compute the contact forces, rebound velocity of a steel ball, and dynamic strain response histories. And low-velocity and high-velocity impact experiments were conducted to compare the results and compute the wave propagation velocities. The results obtained from impact experiments are in good agreement with those of dynamic finite element analysis. Also the wave propagation velocities obtained from high-velocity impact experiments and wave propagation theory agree well, and wave velocities were higher in the smaller radius of steel ball.
The Notched Strength and Fracture Criterion in Plain Woven Glass/Epoxy Composites With a Crack
Journal of Ocean Engineering and Technology, volume 7, issue 2, 1993, Pages 57~67
The fracture behavior of plain woven glass/epoxy composite plates with a crack is investigated under static tensile loading. It is shown in this paper that the characteristic length associated with the point stress criterion depends on the crack length. To predict the not ched tensile strength, the point stress criterion proposed by Whitney and Nuismer are modified. An excellent agreement is found between the experimental results and the analytical prediction of the modified point stress criterion. The condition of unstable crack growth in the presence of a per-existing flaw(machined notch) is examined by means of the maximum stress intensity factor
using maximumload P
. The values of
evaluated from energy release rate G
(the compliance me thod) indicate a wide difference. Therefore in regard to anisotropy and heterogeneity of the composite materials studied, the modified shape correction factor f(a/W) is obtained.
evaluated by the compliance method a little or insignificantly depends on the initial crack length a, the specimen thickness B, the crack angle .theta. and the specimen geometry.
Fatigue Crack shape Variations by a Residual Stress and Fatigue Life Predition
Journal of Ocean Engineering and Technology, volume 7, issue 2, 1993, Pages 68~78
Fatigue crack shape variation by a residual stress during crack growth and life predition are studied. An analytical method is presented to predict the influence of a residual stress due to heattreatment on crack shape variations. Computer simulation results using this me thod are graphically shown that crack growth rate to surface direction are decreased due to compressive residual stress exisiting in surface area. These results are commpared with experimental results. The fatigue life is also predicted by computer simulation of crack aspect ratio variation which is based on the surface crack length increment per unit cycle calculated from a-N diagram. Predited life is about 12 percent lower than experimental life.
A Study for Dynamic Positioning Control of Floating Platform(I)- Numerical Simyulation by a Servo System Design Method -
Journal of Ocean Engineering and Technology, volume 7, issue 2, 1993, Pages 79~90
A design method of DPS control algorithm for adpting rotable thruster is introduced by applying servo system design method and the control algorithm is evaluated on the basis of the results of computer simulations performed for a semi-submersible 2-lower hull 8-column type platform. It is observed from the simulation results that position error due to the irregular drifting forces becomes zero after very short regulating time and dynamic positioning system is robust in spite of random disturbance.
The Evaluation for Elastic-Plastic Fracture Toughness in a Reactor Pressure Vessel Steel(SA508-3)
Journal of Ocean Engineering and Technology, volume 7, issue 2, 1993, Pages 91~102
The elastic-plastic fracture thoughness J sub(IC) of Nuclear Reactor Vessel Steel(SA 508-3) which has high toughness was discussed at temperatures RT,
and 1/2/CT specimen was used for this study. Especially the two methods recommended in ASTM and JSME were compared. It was difficult to find J sub(IC) by ASTM R-curve method with the specimen used for this research, while JSME R-curve method yielded good result. The stretched zone width menthod gave slightly larger J sub(IC) values than those by the R-curve method for SA 508-3 steel.
Failure Analysis in Al 7075-T651 Alloy using X-ray Diffraction Technique
Journal of Ocean Engineering and Technology, volume 7, issue 2, 1993, Pages 103~113
X-ray diffraction analysis technique was used for the fatigue damage analysis and fatigue life prediction in Al 7075-T651 alloy. The tensile test, fatigue strength and fatigue crack propagation test with change of stress ratio were carried out. As a result, half-value breadth was increased with the plastic deformation in the specimen increasint at all test conditions. In particular, half-value breadth at the surface of the specimens fractured by fatigue was increased as stress intensity factor range and effective stress intensity factor range were increased. In addition, the good relationship between half-value breadty and diffraction pattern was shown.
The Numerical Simulation of Muti-directional Wasves and Statistical Investigation
Journal of Ocean Engineering and Technology, volume 7, issue 2, 1993, Pages 114~120
Responses of marine vehicles and ocean structures in a seaway can be predicted by applying the probabilistic approach. When we consider a linear system, the responses in a random seaway can be evaluated through spectral analysis in the frequency domain. But when we treat nonlinear system in irregular waves, it is necessary to get time history of waves. In the previous study we introduced one-directional waves (long crested waves)as wave environment and carried out calculations and experiments in the waves. But the real sea in which marine vehicles and structures are operated has multi-directional waves (short crested waves). It is important to get a simulated random sea and analyse dynamic problems in the sea. We need entire sample function or probabillty density function to infer statistical value of random process. However if the process are ergodic process, we can get statistical values by analysis of one sample function. In this paper, we developed the simulation technique of multi-directional waves and proved that the time history given by this method keep ergodic characteristics by the statistical analysis.
Study on Real-Time Weld Quality Evaluation by Acoustic Emission for Production of Drills by Friction Weldiing
Journal of Ocean Engineering and Technology, volume 7, issue 2, 1993, Pages 121~130
A study off riction welding of high speed steel(SKH 51) bar for blade side to carbon steel(STC 3)bar for shank side was carried out experimentally through tensile test, hardness test, microstructure, and acoustic emission (AE) test. So, this paper deals with optimizing the welding conditions and the real-time quality (strength) evaluation of friction weleded joints by acoustic emission technique. The results obtained are summarized as follows: (1) For friction welded joints of SKH 51to STC 3 steel bars, the total upset (U) increases linearly with an increase of heating time (t sub(1)). (2) The determined optimum welding conditions are heating time (t sub(1)) 7-9 sec, upsetting time (t sub(2)) 5 sec, heating pressure(P sub(1)) 12 kg sub(f)mm supper(2), upsetting pressure (P sub(2)) 15 kg sub(f) mm supper(2) and rotating speed (n) 2, 000 rpm, resulting in a computed relationship between the tensile strength of the joint .sigma. (kg sub(f) mm supper(2)) and the heating time t sub(1) (sec) as the following. sigma.=2.39t sub(1)
The Study on the Influence of the Concentration NaCl Solution on Corrosion Fatigue Behavior of T.M.C.P. Steel
Journal of Ocean Engineering and Technology, volume 7, issue 2, 1993, Pages 131~140
To study the corrosion fatigue begavior of T.M.C.P. steel, the rotary bending fatigue test with the change of concentration of NaCl solution was carried out. Fatigue life in the corrosion environment is decreased markedly in comparision with that in the air. Fatigue limit in the air was about 225 MPa. In case of 3.5% NaCl solution fatigue life could be expressed as .sigma./sub f/=10,392 * (N/sub f/)/sup -o.2923 . According to the paris's rule, crack growth rates could be expressed as da/dN=2.62.*10/sup -7/ .DELTA. K/sup 1.09/(3.5% NaCl solution), da/dN=1.95 *10/sup -7 .DELTA. K/sup 1.05/(1% NaCl solution), da/dN=2.62 * 10/sup -7/.DELTA./sup 0.72/(0.01% NaCl solution) with da/dN expressed in mm/cycle and .DELTA.K in MPa.GAMMA.m. The crack growth rate in the corrosion environment was highest under 3.5% NaCl solution.
Prediction of the Out-of-plane Motion due to the In-plane Excitation
Oh, Il-Geun ;
Journal of Ocean Engineering and Technology, volume 7, issue 2, 1993, Pages 141~149
Numerical Computation of Laminar Flow over a Backward Facing Step
Van, Suck-Ho ;
Journal of Ocean Engineering and Technology, volume 7, issue 2, 1993, Pages 150~161
Numerical Simulation of Colliding Behaviors of Ice Sheet Considering the Viscous Material Properties
Journal of Ocean Engineering and Technology, volume 7, issue 2, 1993, Pages 162~172
In the present paper, the overall state of the arts of ice mechanics which is the most typical research topic of the artic engineering field was studied. And also, ice loads genrated by ice-structure interaction were estimated using numerical approach. The effects of viscous property of ice sheets to the ice load were investigated. The time dependent deformation behaviors of ice was modeled by visco-plastic problem using the finite element formalism. Constitutive model representing the material properties of ice was idealized by comblned rheological model with Maxwell and Voigt models. Numerical calculations for the bending and crushing behavior of ice sheet which are the most typical interaction modes between ice sheets and structures were carried out. The time dependent viscous behaviors of ice sheets interaction forces acting on structures were analyzed and the results were studied in detail.
Growth Characteristics and Life Prediction of Single Surface Fatigue Crack with the Variation of crack Configuration Ratios
Journal of Ocean Engineering and Technology, volume 7, issue 2, 1993, Pages 173~181
This work has been investigated the ralationship between single surface crack length and crack depth have influence on the fatigue life. The simulation based on experimental results of 2.25 Cr-1Mo steel at various crack configuration ratios has enabled successful prediction of fatigue life at room temperature. The effect of crack depth should be considered for predicting fatigue crack growth rates as well as that of surface crack length. It is also shwn that the crack growth mechanisms are in good agreement with expreimental data according to the interaction of crack length and crack depth.