• The Journal of the Acoustical Society of Korea
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• v.31 no.1
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• pp.11-18
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• 2012

In this paper, the occurrence of a stopband phenomenon when an acoustic wave propagates through periodically corrugated ducts is discussed using theoretical and BEM analyses. A 2-D duct with sinusoidally corrugated upper and lower walls is considered. When the magnitude of the sinusoidal corrugation is sufficiently small compared to the duct's height, the wave equation is solved with the multiple scaling perturbation method. Then stopbands for Bragg and non-Bragg resonances are computed from the condition where frequency becomes a complex number. A 2-D BEM analysis is performed to compute insertion loss of the duct, and stopbands are confirmed as predicted by analytical analysis.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.3
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• pp.279-289
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• 2009

For a Product Oil Carrier, longitudinal bulkhead as well as transverse one is corrugated shape in general and intersection part of bulkheads is utilized for a pipe trunk. Since lower and upper stools are to be connected with all of longitudinal and transverse bulkheads, they have a uniform height respectively. The purpose of this study is the development of design system for the minimization of total weight of longitudinal and transverse bulkheads at the initial design stage. In this study, the beam element models for longitudinal and transverse corrugated bulkheads are established and they are applied to the structural analysis. For the practical design, the selection and the position of an additional pipe trunk are considered in this study. In addition the required minimum distance between the bracket installed along the web of corrugation at lower stool and the diaphragm is taken into consideration during optimization process. Evolution strategy(ES) is adopted as an optimization technique.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.6
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• pp.735-749
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• 2008

For the development of the original technique of structural safety assessment of Cargo Containment System(CCS) in membrane type LNG carriers, it is necessary to understand the characteristics of dynamic response behavior of CCS structure under sloshing impact pressure. In the previous study, the wet drop impact response analyses of CCS structure in membrane Mark III type LNG carriers were carried out by using Fluid-Structure Interaction(FSI) analysis technique of LS-DYNA code, and were also validated through a series of wet drop experiments for the enhancement of more accurate shock response analysis technique. In this study, the characteristics of structural shock response behaviors of CCS structure were sufficiently figured out by careful examinations of the effects of specimen weight, drop height, incident angle, corrugation and stiffness of inner hull on its shock response behaviors. The shock response analysis of upward shooting fluid to inner hull was performed, and the reason of faster strain response than shock pressure one was also figured out.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1327-1336
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• 2013

In this study, the effects of corrugated webs on the ultimate behavior of horizontally curved I-shaped girders are investigated. Because of the geometric characteristics of corrugated plates, corrugated webs can be used for enhancing torsional and warping stiffness of plate girders. Many researches have been conducted to study the effects of corrugated webs on the ultimate behavior of straight girders. But, the studies of the ultimate behavior of horizontally curved girders with corrugated webs, which generally show out-of plane behavior manly, have been rarely performed so far. By performing inelastic-nonlinear analysis, the ultimate behavior of curved girders with corrugated webs is studied in this paper. Laterally unsupported length and subtended angle of girders, and length of height of corrugation of webs are considered as the geometric parameters which would be expected to affect the ultimate behavior. By this analytical study with considering the geometric parameters, the changes of ultimate behavior and load carrying capacity of curved girders with corrugated webs are investigated. Also, the effects of corrugated webs on the increase of load carrying capacity for curved girders are studied with comparing to the capacity of general curved girders with flat webs. According to the analytical results, corrugated webs can be used to increase the ultimate load carrying capacity of curved girders, because of their high torsional and warping stiffness. But, it is also indicated that they may decrease the load carrying capacity of curved girders which have relatively small subtended angle or initial curvature, because of an accordion effect.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.1
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• pp.39-45
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• 2024

Seismic safety of expansion joints for piping systems has been underscored by water pipe ruptures and leaks resulting from the Gyeongju and Pohang earthquakes. Metal bellows in piping systems are applied to prevent damage from earthquakes and road subsidence in soft ground. Designed with a series of corrugated segments called convolutions, metal bellows exhibit flexibility to accommodate displacements. Several studies have examined variations in convolution shapes and layers based on the intended performance to be evaluated. Nonetheless, the research on the seismic performance of complex bellows having multiple corrugation heights is limited. In this study, monotonic loading tests, cyclic loading tests, and fatigue tests were conducted to evaluate the shear performance in seismic conditions, of metal bellows with variable convolution heights. Single- and triple-layer bellows were considered for the experimentation. The results reveal that triple-layer bellows exhibit larger maximum deformation and fatigue life than single-layer bellows. However, the high stiffness of triple-layer bellows in resisting internal pressure poses certain disadvantages. The convolutions are less flexible at lower displacements and experience leakage at a rate related to the variable height of the convolutions in certain conditions. At lower deformation rates, the fatigue life is rated higher as the number of layers increase. It converges to a similar fatigue life at higher deformation rates.