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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Ocean Engineering and Technology
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Journal DOI :
Korean Society of Ocean Engineers
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Volume & Issues
Volume 9, Issue 2 - Dec 1995
Volume 9, Issue 1 - Jun 1995
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Analysis of Offshore Tubulars Subjected to Collision Impacts Using a Spring-Beam Model
Journal of Ocean Engineering and Technology, volume 9, issue 1, 1995, Pages 22~35
A simplified numerical procedure have proposed to trace the dynamic behaviour of offshore tubulars subjected to lateral collision impacts. The local denting and overall bending deformation of the struck tubular are represented by a non-linear spring and an elastic visco-plastic beam respectively. In this method a temporal finite difference method and a spacial finite element method are employed. Using this method various boundary conditions are able to considered and their effects on the extent of damage can be quantified. The extent of damage due to collision can be obtained as results of the dynamic analysis. The predictions using the proposed method have been correlated with existing test results and then the reliability of the procedure has been substantiated. The characteristics of the dynamic response of tubulars under lateral impacts are compared for simply supported roller and fixed end conditions and their effects on the extent of damage are specfied.
Numerical Study on Ice/Structure Interaction Behaviour in Dynamic ice Field
Jo, Chul H. ;
Journal of Ocean Engineering and Technology, volume 9, issue 1, 1995, Pages 36~46
The Evaluation of Strength and Damage Characteristics by AE in Impact Test of CFRP
Journal of Ocean Engineering and Technology, volume 9, issue 1, 1995, Pages 47~56
This study is aimed to have a database of system development for the prediction, monitoring, analyzing, and evaluation of tensile strength and damage characteristics through AE technique for CFRP. Therefore the correlations between impact characteristics (such as impact velocity, impact energy, delamination area etc) and AE signals for CFRP laminates were investigated. And also it were accomplished the evaluation of tensile strength and the investigation on correlation with AE signals for impact damaged specimen of CFRP laminates.
The Influence of Hygrothermal Effect to Residual Strength GFRP Composites
Journal of Ocean Engineering and Technology, volume 9, issue 1, 1995, Pages 57~62
The hygrothermal effect on three different types of Glass/Polypropylene was investigated under the environment of 4
distilled water. The residual strength of Glass/Polypropylene with randomly oriented and fiber content of 4-wt%(R40) was found stable under the moisture content of 0.2%. In this case, the maximum moisture content was 0.53%. On the other hand, Glass/Polypropylene with unidirection and 42wt%(U42) and 50st%(U50) fiber content, respectively, showed the residual strength less stable than R40. However, the maximam moisture contents were 0.52% and 0.45% respectively.
An Experimental Study on the Growth Behavior of Multi-Surface-Cracks in Type 304 Stainless Steel at Elevated Temperature
Journal of Ocean Engineering and Technology, volume 9, issue 1, 1995, Pages 63~72
The crack which is discovered in various structures and machine elements is multi-cracks. Multi-cracks may cause serious problems because they grow individually, and coalesce into one and it leads to fracture. Fatigue tests have been carried out to study the growth and coalescence behavior of multi-surface-cracks initiated at the semicircular surface notch in type 304 stainless steel at elevated temperature. The results are as follows; When multi-surface-cracks are lying on the surface of material, the major surface crack has greater influence on the fatigue life than the subcracks. The aspect ratio of multi-surface-cracks is lower than that of single crack because of the interaction and coalescence of surface cracks. Crack growth shape turns to semiellipse from the semicircle notch. After coalescence, the surface crack length increases rapidly, and it leads to fracture. Further, the slope transition of Paris law was found in the da/dN-
Application of High-Order Target Dynamics to Position and Force Control of a Manipulator
Lee, Sang-Moo ;
Journal of Ocean Engineering and Technology, volume 9, issue 1, 1995, Pages 73~82
The Fatigue Behavior by Variety of Crack Length of Surface Cracked Plate with Stress Concentration Part
Journal of Ocean Engineering and Technology, volume 9, issue 1, 1995, Pages 83~91
Surface defects in structural members are apt to be origins of fatigue cracks growth, which may cause serious failure of whole structures. Most structure has a part where stress concentrates such as welded joints, corner parts, etc. And then, analysis on crack growth and penetration from these defects, therefore, is one of the most important subjects for the reliability of LBB design. The present paper has performed an experimental and analysis on the fatigue crack propagation by variety in crack length of surface cracked plate with stress concentration part. The crack growth behavior can be explained quantitatively by using Newman-Raju equation and the stress partitioning method proposed by ASME B&P Code Sec. XI. The stress concentration factor
has affected on the crack growth. The crack growth after penetration depends upon the initial front side crack length.
A Study on Fatigue Crack Propagation Behavior with Pure-Ti Plate
Journal of Ocean Engineering and Technology, volume 9, issue 1, 1995, Pages 92~100
The effect of different anisotropy and stress ratio on fatigue crack propagation behavior was investigated under various stress ratio(R=-0.4, -0.2, 0.2, 0.2, 0.4) using pure titanium sheet used in aerospace, chemical and food industry. The rack closure behavior under constant load amplitude fatigue crack propagation test was examined. Fatigue crack propagation rate da/dN was estimated in terms of effective stress intensity factor range,
, regardless of various stress ratio but was influenced by anisotropy. Also, it was found that the effect of anisotropy was considerably decreased but still not negligible when he da/dN was evaluated by a conventional parameter,
/E and when the modified da/dN.
was evaluated by
/E. On the other hand, da/dN could be evaluated uniquely by effective new parameter,
, regardless of anisotropy, as int he following equation da/dN= C"[
] n". And effective stress intensity factor range ratio, U was estimated by the following equation with respect to the ratio of reversed plastic zone size,
to monotonic plastic zone size,
regardless of stress ratio and anisotropy. U=-4.45
The Effect of Pre-strain on Cyclic Deformation Characteristic of Ti-Ni Alloy
Journal of Ocean Engineering and Technology, volume 9, issue 1, 1995, Pages 101~110
In SMA(Shape Memory Alloy), the degradation by fatigue is one of the most important problems to be overcome, when SMA is used for robot-actuator materials. The actuator is operated repetitively for long time and its repeating operation develops the fatigue degradation of SMA. The fatigue degradation changes the transformation temperature and deformation behavior and results in inaccurate operation and deformation which results form repeating operation is to be investigated in advance and the scheme to resolve those problems have to be made for the design of actuator. In this paper, for the improvement of the fatigue degradation by repetive movement and better control of the correct movement by the stability of martensite transformation in the development of Robots actuator, Pre-strain(0, 1.5, 5, 8%) are loaded in the specimens and fatigue testing were carried out by the method of heating and cooling in direct condition. From the results of these experiments, the effect on pre-strain which affect the transformation characteristic and fatigue degradation phenomena were correctly investigated.
A method of Determination of Fracture Toughness of Reactor Pressure Vessel Steel by J Integral
Journal of Ocean Engineering and Technology, volume 9, issue 1, 1995, Pages 111~119
The elastic-plastic fracture toughness(
) and fracture resistance (J-R curve) of SA508-3 alloy steel used for nuclear reactor pressure vessel are investigated by using CT-type specimens. Fracture toughness tests are conducted by unloading compliance method and multiple specimen method at room temperature, -2
. The apparent negative crack growth phenomenon which usually arises in partial unloading compliance test is well known. The negative crack growth phenomenon in determining J sub(IC) or J-R cure from partial unloading compliance experiments may be eliminated by the offset technique. In this study, the evaluation of
multiple specimen method recommended by the JSME gives the most reliable results by using half-size CT(similar-type) specimens.
A Study on the Suspended Sediment Transport in the Nakdong Estuary
Journal of Ocean Engineering and Technology, volume 9, issue 1, 1995, Pages 120~131
Numerical simulations on the suspended sediment transport in the Nakdong Estuary are carried out Uncoupled flow model and diffusion model of which the governing equations are two-dimensional depth integrated equations are used int his study. Four cases are tested in this numerical simulations in which the Gaduk waterway open boundary condition and Nakdong Estuary barrage boundary condition are considered as the boundary conditions. The simulated results are compared with the measured data which were obtained by NEDECO at hadan site on 1981.2.19. and by Dong-A university at one station in the study area on 1993.4.3. and show a good agreement with them. The construction of the Nakdong Estuary Barrage may affect to reduce the current near Jinudo an Daemadeung and the suspended sediment inflowed from the upstream in the wet season seems to be transported to the Dadae.
A Stochastic Study on Fatigue Crack Propagation and Retardation Behavior of Pressure Vessel Steel
Journal of Ocean Engineering and Technology, volume 9, issue 1, 1995, Pages 132~141
The purpose of the present study is to investigate the statistical characteristics of m and C in the fatigue crack propagation law, da/dN=C(.DELTA.K)/sup m/ and to studies on the randomness of fatigue crack propagation and retardation behavior. Fatigue tests were perfomed on 32 CT specimens of SPV50 steel under the same one condition. First, the value of m and C were determined for each specimen, and all the data were analyzed statistically. second, the material's resistance to fatigue crack propagation is modeled as a stchastic process, which varies randomly along the crack path. The statistical analysis of the material resistance is performed with the data obtained by constant load controlled tests. Finally, retardation behavior was examined experimentally by using a CT specimen, and a retardation parameters were analyzed statistically.
Fatigue Crack Growth, Coalescence Behavior and its Simulation on Multi-Surface Cracks Under the Elevated Temperature
Journal of Ocean Engineering and Technology, volume 9, issue 1, 1995, Pages 142~151
A simulation program concerned with multi-surface fatigue cracks which initiated at the semi-circular surface notches has been developed to predict their growth and coalescence behaviors at the elevated temperature. Three kinds of coalescence models such as SPC(surface point connection), ASME and BSI(British Standards Institution) conditions were applied, and the results of the simulation were compared with those of the experiment. This simulation is able to enhance the reliance and integrity of structures especially under the elevated temperature which have lots of difficulties in experiments and applications. This shows that the simulation result has utility for fatigue life prediction. Even though all the specimens were the same shape, the error rate was increased in accordance with the applied stress to the specimen. Among the material constants C and m in the narrow band, the results applied upper values of the band to the simulation has shown quite small error compared with the experiment results.
Low Temperature Impact Toughness and Stress Corrosion Resistance in Duplex Stainless Steel Welds
Journal of Ocean Engineering and Technology, volume 9, issue 1, 1995, Pages 151~160
The characteristics of low temperature impact toughness and stress corrosion resistance at boiling MgCl
solution of GTA and SMA weld of duplex stainless steels have been investigated. The impact toughness was highest at the GTAW weld metal and lowest at the SMAW weld, which was almost the same as that of the SMAW heat-affected zone. This was attributable to influence of austenite-ferrite phase balance, and the degree and nature of precipitation that occurred during welding. The SCC resistance of the weldments was slightly higher than that of the base metal, whereas no difference in the SCC resistance was found between two different weldments.
Low Temperature Impact Toughness and Stress Corrosion Resistance in Duplex Stainless Steel Welds
Kim, Hyo Jong ; Lee, Seong Geun ;
Journal of Ocean Engineering and Technology, volume 9, issue 1, 1995, Pages 152~152
A Dynamic Response Analysis of Tension Leg Platforms in Waves (I)
Journal of Ocean Engineering and Technology, volume 9, issue 1, 1995, Pages 161~172
A numerical procedure is described fro predicting the motion and structural responses of tension leg platforms(TLPs) in waves. The developed numerical approach is based on a combination of a three dimensional source distribution method and the dynamic response analysis method, in which the superstructure of TLPs is assumed flexible instead of the rigid body assumption used in tow-step analysis method. Both the hydrodynamic interactions among TLP members, such as columns and pontoons, and the structural whole structure are formulated using element-fixed coordinate systems which have the origin at the node of the each hull element and move parallel to a space-fixed coordinate system. Numerical results are compared with the experimental and numerical ones, which are obtained in the literature, concerning the motion and structural responses of a TLP in waves. The results of comparison confirmed the validity of the proposed approach.