• Fibers and Polymers
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• 제7권2호
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• pp.123-128
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• 2006

The present study aims at characterizing and modeling the anisotropic creep behavior of coated textile membrane, a class of flexible textile composites that are used for moderate span enclosures (roofs and air-halls). The objective is to develop a creep model for predicting the lifetime of coated textile membrane. Uniaxial creep tests were conducted on three off-axis coupon specimens to obtain the directional creep compliance. A potential with three parameters is shown to be adequate for modeling the anisotropic creep behavior of coated textile membrane. Furthermore, a possibility of predicting the creep deformation of coated textile membrane in a multi-axial stress state is discussed using the three-parameter potential.

• 한국공간구조학회:학술대회논문집
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• 한국공간구조학회 2006년도 춘계 학술발표회 논문집 제3권1호(통권3호)
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• pp.205-213
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• 2006

Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The design procedure of membrane structures are needed to do shape finding, stress-deformation analysis and cutting pattern generation, because the material property has strong axial stiffness, but little bending stiffness. The problem of cutting pattern is highly varied in their size, curvature and material stiffness. So, the approximation inherent in cooing pattern generation methods is quite different. Therefore the ordinary computer software of structural analysis & design is not suitable for membrane structures. In this study, we develop the program for cutting pattern generation using geodesic line, and investigate the result of example's cutting pattern in detail.

• 한국해양공학회지
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• 제15권2호
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• pp.22-32
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• 2001

The numerical investigation of obliquely incident wave interactions with fully submerged dual buoy/porous-membrane floating breakwaters placed in parallel with spacing is studied based on linear potential theory and Darcy's law. The numerical solutions are obtained by using a discrete-membrane dynamic model and second-kind modified Bessel function distribution over the entire boundaries of fluid regions. First, numerical solutions for an idealized dual submerged system without buoys are obtained. Second, a more practical dual submerged system with membrane tension provided by buoys at its tops is investigated by the multi-domain boundary element method particularly devised for dual buoy/porous-membrane problems with gaps. The velocity potentials of wave motion are coupled with porous-membrane deformation, and solved simultaneously since the boundary condition on porous-membrane is not known in advance. The effects of varying permeability on membranes and wave characteristics are discussed for the optimum design parameters of systems previously studied. The inclusion of permeability on membrane eliminates the resonances that aggravate the breakwater performance. The system is highly efficient when waves generated by the buoys and membranes were mutually canceled and its energy at resonance frequency dissipates through fine pores on membranes.

• Fibers and Polymers
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• 제1권1호
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• pp.45-54
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• 2000

Impact behaviors of the large deformable composites of Kevlar fiber reinforced composites of different preform structures have been investigated. An analytic tool was developed to characterize the impact behavior of the Kevlar composites. The image analysis technique, and deply technique were employed to develop energy balance equation under impact loading. An energy method was employed to establish the impact energy absorption mechanism of Kevlar multiaxial warp knitted composites. The total impact energy was classified into four categories including delamination energy, membrane energy, bending energy and rebounding energy under low velocity impact. Membrane and bending energy were calculated from the image analysis of the deformed shape of impacted specimen and delamination energy was calculated using the deplying technique. Also, the impact behavior of Kevlar composites under high velocity impact of full penetration of the composite specimen was studied. The energy absorption mechanisms under high velocity impact were modelled and the absorbed energy was classified into global deformation energy, shear-out energy, deformation energy and fiber breakage energy. The total energy obtained from the model corresponded reasonably well with the experimental results.

• KCI Concrete Journal
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• 제11권3호
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• pp.53-64
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• 1999

A theory is proposed to predict the response of the load-deformation relationship of the reinforced concrete structures under the service state after cracking. The crack direction and concrete strains through the loading history before failure can be estimated by this theory based on the rotating crack model, which considers equilibrium, compatibility conditions, and average stress-strain relationship. The proposed crack direction and deformation show good agreement with test results under service state. The behavior of a variety of concrete structures, such as shear walls, deep beams and the web of box girders, can be predicted by this proposed theory under service state.

• 한국가스학회:학술대회논문집
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• 한국가스학회 2001년도 추계학술발표회 논문집
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• pp.16-22
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• 2001

LNG demand has been rapidly increasing in Korea for a variety of reaso including stable supply, non- polluting, and high combustion efficiency characteris As a result the construction and expansion of LNG storage facilities have b continuing at a vigorous pace. One of the most important structural core elemen the LNG storage tank is the membrane, consisting of stainless steel. The memb to be applied inside of LNG storage tank is provided with corrugations to abs thermal contraction and expansion caused by LNG temperature. From the viewp of strength design, however. it is essential to confirm that the membrane undergo a stable deformation and has a sufficient fatigue strength Experim studies are presented to investigate the deformation and strength of the memb which is designed by Kogas. All experiments are conducted on the basis of RP and we found the results is fully satisfied with the RPIS.

• 드라이브 ㆍ 컨트롤
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• 제16권4호
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• pp.65-73
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• 2019

In this study, flow analysis and fluid-solid interaction analysis were conducted on a hollow fiber membrane module used for analysis of dehumidification characteristics. To ensure the reliability of the flow analysis results, the dehumidification experiment was performed under the temperature of 30℃ and relative humidity of 30% RH. The results of the dehumidification experiments were compared with the flow analysis results. The results of dehumidification experiments and flow analysis had a difference of approximately 5%. A 1-Way fluid-solid interaction analysis with various materials was conducted. From the results, it was found that the baffle with the largest shape deformation (polyethylene material) was subjected to 2-way fluid-solid interaction. The analysis of fluid flow and dehumidification characteristics were analyzed according to the shape deformation of the baffle.

• 대한기계학회논문집
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• 제18권10호
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• pp.2653-2663
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• 1994

The design of sheet metal working processes is based on the knowledge about the deformation mechanism and the influence of the process parameters. The typical geometric process parameters are the die geometry, the initial sheet thickness, the initial blank shape, and so on. The initial blank shape is of vital importance in the most sheet metal forming operations, especially in the deep drawing process, since the forming load and the strain distribution are significantly affected by the shape of an initial blank. The influence of the initial blank shape on a square cup deep drawing process is investigated by the numerical simulation and the experiment. The numerical simulation is carried out by a modified membrane finite element method which takes bending deformation into account. The numerical and experi-mental results show that the initial blank shape have strong influence on the forming load and the strain distribution. The numerical results are compared with the experimental results and other numerical results which are calculated with the membrane theory.

• Computers and Concrete
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• 제31권3호
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• pp.223-239
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• 2023

Geometric nonlinear performance simulation and analysis of complex modern buildings and industrial products require high-performance shell elements. Balancing multiple aspects of performance in the one geometric nonlinear analysis element remains challenging. We present a new shell element, flat shell DKMGQ-CR (Co-rotational Discrete Kirchhoff-Mindlin Generalized Conforming Quadrilateral), for linear and geometric nonlinear analysis of both thick and thin shells. The DKMGQ-CR shell element was developed by combining the advantages of high-performance membrane and plate elements in a unified coordinate system and introducing the co-rotational formulation to adapt to large deformation analysis. The effectiveness of linear and geometric nonlinear analysis by DKMGQ-CR is verified through the tests of several classical numerical benchmarks. The computational results show that the proposed new element adapts to mesh distortion and effectively alleviates shear and membrane locking problems in linear and geometric nonlinear analysis. Furthermore, the DKMGQ-CR demonstrates high performance in analyzing thick and thin shells. The proposed element DKMGQ-CR is expected to provide an accurate, efficient, and convenient tool for the geometric nonlinear analysis of shells.

• 한국해안·해양공학회논문집
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• 제21권4호
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• pp.290-300
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• 2009

연직 막체방파제에 대한 기존의 수치해석에서는 막체의 운동 중 발생하는 변동장력성분이 초기장력에 비하여 미미하다는 가정 하에 운동 중의 막체 장력을 초기장력으로 대체하는 선형해석을 수행하였다. 본 수치해 석에서는 막체장력의 비선형 변화를 한 주기 동안의 평균장력으로 대체하며 이 평균장력을 반복계산을 통하여 구해나가는 준 비선형 해석을 수행하였다. 상기 선형해석 결과와 비교하여 입사파 주기가 증가할수록 반사율은 증가하며 전달율은 감소하는 것으로 나타났다. 아울러, 본 준 비선형해석을 계류형태를 달리하는 두 구조물에 적용한 결과, 막체의 수평변위의 제어가 방파성능에 밀접한 효과가 있는 것으로 나타났다. 막체의 수평변위를 억제하기 위해서는 막체의 초기장력을 증가시키거나 막체의 중간부에 계류라인을 추가 결속시키는 방법들이 있으나 이를 위해서는 연직 하향 계류력을 지지하기 위한 대형 수면 부표의 설치가 요구된다.