• Title/Summary/Keyword: finite-element numerical modeling

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Combined Extended and Superimposed Finite Element Method for Crack Analysis (균열해석을 위한 겹침확장 유한요소법)

  • 이상호;송정훈;허문석
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2004.04a
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    • pp.341-348
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    • 2004
  • This paper presents a modeling technique of cracks by combined extended and superposed finite element method (XSFEM) which is a combination of the extended finite element method (XFEM) and the mesh superposition method (sversion FEM). In the proposed method, the near-tip field is modeled by a superimposed patch consisting of quarter point elements and the rest of the discontinuity is treated by the XFEM. The actual crack opening in this method is measured by the sum of the crack openings of XFEM and SFEM in transition region. This method retains the strong point of the XFEM so it can avoid remeshing in crack evolution and trace the crack growth by translation or rotation of the overlaid mesh and the update of the nodes to be enriched by step functions. Moreover, the quadrature of the Galerkin weak form becomes simpler. Numerical experiments are provided to demonstrate the effectiveness and robustness of the proposed method.

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Mooring loads analysis of submersible aquaculture cage system using finite element method

  • Kim, Tae-Ho
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.42 no.1
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    • pp.44-53
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    • 2006
  • The expansion of near shore aquaculture is feasibility of moving aquaculture facilities into the open ocean. Numerical modeling technique using finite element method was used to enable the optimum design and evaluation of submersible aquaculture cage system. The characteristics of mooring loads response in mooring lines under waves and current and their response amplitude operators were calculated for single and three point mooring configuration at the surface condition and submerged one. The static mooring loads without wave and current loading were similar for both the surface and submerged configuration. It was calculated that three point mooring was more adequate than single point mooring for the mooring configuration of submersible aquaculture cage system. The wave induced response amplitude operators for the single point mooring configuration with the influence of currents were identical to those without the influence of currents.

FINITE ELEMENT MODELING FOR HYDRODYNAMIC AND SEDIMENT TRANSPORT ANALYSIS (II) : SEDIMENT TRANSPORT STUDY

  • Noh, Joon-Woon
    • Water Engineering Research
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    • v.4 no.2
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    • pp.99-109
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    • 2003
  • Since bed elevation changes are mainly dependent on the flow velocity and corresponding shear stress, it is possible to predict bed elevation numerically using velocity components. For the scour analysis due to channel contraction, a bed load transport model is developed and applied to estimate scour depth around coffer dam in the Mississippi River. During Phase I of the Lock & Dam No. 26 replacement project, a coffer dam was constructed to reduce the flow area approximately by 50%. Flow velocity increases due to the flow area reduction yields significant lowering (erosion) of the channel bed elevation. The proposed numerical model solves the sediment continuity equation using the finite element method to evaluate scour process in the vicinity of the coffer dam

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The Finite Element Analysis of Car Seat Frame According to The FMVSS Strength Test (FMVSS 강도테스트에 다른 자동차 시트프레임의 유한요소해석)

  • 이호용;임중연;범형택
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.6
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    • pp.241-247
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    • 1999
  • This study presents the structural analysis of car a seat frame by the finite element method. The load-deformation characteristics of seat frame are simulated according to the test requirements by FMVSS. Three dimensional modeling technique is applied to the components of the seat frame. The shell, solid , gap and rigid elements are employed to model the car seat frame assembly. Numerical results show that the recliner and kunckle plate are identified as the possible weak part of frame, and the results are well consistent with the experimental static load test. The current analysis model can provide useful informations to design a new car seat and can reduce the overall design cost and time.

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Parameter Investigation for Powder Compaction using Discrete-Finite Element Analysis

  • Choi, Jinnil
    • Journal of Powder Materials
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    • v.22 no.5
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    • pp.337-343
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    • 2015
  • Powder compaction is a continually and rapidly evolving technology where it is a highly developed method of manufacturing reliable components. To understand existing mechanisms for compaction, parameter investigation is required. Experimental investigations on powder compaction process, followed by numerical modeling of compaction are presented in this paper. The experimental work explores compression characteristics of soft and hard ductile powder materials. In order to account for deformation, fracture and movement of the particles, a discrete-finite element analysis model is defined to reflect the experimental data and to enable investigations on mechanisms present at the particle level. Effects of important simulation factors and process parameters, such as particle count, time step, particle discretization, and particle size on the powder compaction procedure have been explored.

Analysis of Densification Behavior of Magnesium Powders in Extrusion using the Critical Relative Density Model (임계상대밀도모델을 이용한 마그네슘분말의 압출공정 치밀화 거동)

  • Yoon, Seung-Chae;Chae, Hong-Jun;Kim, Taek-Soo;Kim, Hyoung-Seop
    • Journal of Powder Materials
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    • v.16 no.1
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    • pp.50-55
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    • 2009
  • Numerical simulations of the powder extrusion need an appropriate pressure-dependent constitutive model for densification modeling of the magnesium powders. The present research investigated the effect of representative powder yield function of the critical relative density model. We could obtain reasonable physical properties of pure magnesium powders using cold isostatic pressing. The proposed densification model was implemented into the finite element code. The finite element analysis was applied to simulation of powder extrusion of pure magnesium powder in order to investigate the densification and processing load at room temperature.

Finite Element Analysis on Concrete Fracture using Homogenized Crack Model (혼합균열모델을 적응한 콘크리트 파괴의 유한요소해석)

  • 송하원;방춘석
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2003.04a
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    • pp.137-144
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    • 2003
  • Since quasi-brittle material like concrete shows strain localization behavior accompanied by strain softening, a numerical drawback such as mesh sensitivity is appeared in the finite element analysis. In this study, a homogenized crack model which overcomes the drawback and considers rate discontinuity in the constitutive equation is proposed for modeling of cracking in concrete and its propagation in strain softening regime. Then, a series of finite element analysis of the concrete under various loading conditions has been performed. From comparison of analysis results with experimental data, it is shown that failure behavior due to localized cracking of concrete under both compressive loading condition and tensile loading condition is well predicted by the homogenized crack model.

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Strength and Crack Growth Computation for Various types of Stringers for Stiffened Panels using XFEM Techniques

  • Krishna, Lok S;Reshma, G;Dattaguru, B
    • International Journal of Aerospace System Engineering
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    • v.7 no.1
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    • pp.7-15
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    • 2020
  • In this paper the crack growth, modeling, and simulation of the stiffened and un-stiffened cracked panels presented using commercially available finite element software packages. Computation of stresses and convergence of stress intensity factor for single edge notch (SEN) specimens carried out using the finite element method (FEM) and extended finite element method (XFEM) and compared with an analytical solution. XFEM techniques like cohesive segment method and LEFM using virtual crack closure technique (VCCT), used for crack growth analysis and presented results for un-stiffened and stiffened panels considering various crack domain. The non-linear analysis considering both geometric and material non-linearity on stiffened panels with various stringers like a blade, L, inverted T and Z sections the results were presented. Arrived at the optimum stringer section type for the considered panel under axial loading from the numerical analysis.

Finite element modeling of the vibrational behavior of multi-walled nested silicon-carbide and carbon nanotubes

  • Nikkar, Abed;Rouhi, Saeed;Ansari, Reza
    • Structural Engineering and Mechanics
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    • v.64 no.3
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    • pp.329-337
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    • 2017
  • This study concerns the vibrational behavior of multi-walled nested silicon-carbide and carbon nanotubes using the finite element method. The beam elements are used to model the carbon-carbon and silicon-carbon bonds. Besides, spring elements are employed to simulate the van der Waals interactions between walls. The effects of nanotube arrangement, number of walls, geometrical parameters and boundary conditions on the frequencies of nested silicon-carbide and carbon nanotubes are investigated. It is shown that the double-walled nanotubes have larger frequencies than triple-walled nanotubes. Besides, replacing silicon carbide layers with carbon layers leads to increasing the frequencies of nested silicon-carbide and carbon nanotubes. Comparing the first ten mode shapes of nested nanotubes, it is observed that the mode shapes of armchair and zigzag nanotubes are almost the same.

Seismic Analysis of an Axial Blower Using a Commercial FEM Code (상용 유한요소해석 프로그램을 이용한 축류송풍기의 내진해석)

  • 정진태;임형빈;김강성;허진욱
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.3
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    • pp.181-186
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    • 2002
  • A seismic analysis is one of crucial design procedures of an axial blower used in nuclear power Plants. The blower should be operated even in ar emergency such as an earthquake. The blower should be designed in order to stand against an earthquake. For the seismic analysis, Ive perform the modal analysis and then evaluate the required response spectrum (PRS) from the given floor response spectrum (FRS). A finite element model of the blower is established by using a commercial FEM code of ANSYS. After the finite element modeling. the natural frequencies. the mode shapes and the participation factors are obtained from the modal analysis. The PRS is acquired by a numerical approach on the basis of the principle of mode superposition. We verify the structura safety of the axial blower and confirm the validity of the present seismic analysis results.