• Title/Summary/Keyword: solid elements

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A Study on Improvement of Flow Characteristics for Thin-Wall Injection Molding by Rapid Mold Heating (급속 금형가열에 의한 박육 사출성형의 유동특성 개선에 관한 연구)

  • Park Keun;Kim Byung H.
    • Transactions of Materials Processing
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    • v.15 no.1 s.82
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    • pp.15-20
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    • 2006
  • The rapid thermal response (RTR) molding is a novel process developed to raise the temperature of mold surface rapidly to the polymer melt temperature prior to the injection stage and then cool rapidly to the ejection temperature. The resulting filling process is achieved inside a hot mold cavity by prohibiting formation of frozen layer so as to enable thin wall injection molding without filling difficulty. The present work covers flow simulation of thin wall injection molding using the RTR molding process. In order to take into account the effects of thermal boundary conditions of the RTR mold, coupled analysis with transient heat transfer simulation is suggested and compared with conventional isothermal analysis. The proposed coupled simulation approach based on solid elements provides reliable thin wall flow estimation for both the conventional molding and the RTR molding processes.

Sonographic Findings of Thyroid Papillary Carcinoma (갑상선 유두암의 초음파 소견)

  • Lee, Jae-Kyo
    • Journal of Yeungnam Medical Science
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    • v.21 no.2
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    • pp.224-230
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    • 2004
  • Background: To determine the various sonographic findings in a papillary carcinoma of the thyroid. Materials and Methods: 48 patients with a proven papillary carcinoma of the thyroid were involved. The sonographic features analyzed were the size, shape, content, margin, internal echo, and calcification pattern. Results: Common sonographic features of a papillary carcinoma include the hypoechoic texture (94%), an ill defined margin (81%), a solid nodule (100%), irregular shape (48%), and microcalcifications (35%), or no calcifications (42%). The uncommon features included a hyperechoic or mixed echo texture, cystic elements, a well defined margin, and a coarse or peripheral calcifications. Conclusion: Ill-defined hypoechoic solid nodule with microcalcification is a characteristic ultrasonographic finding of a thyroid papillary carcinoma.

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Stent modeling and simulation of truss structure using SMA (형상기억합금 트러스 구조물을 이용한 스텐트의 설계 및 해석)

  • Yang, Seong-Pil;Kim, Sang-Haun;Cho, Mang-Hyo
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.518-522
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    • 2008
  • Recently, many patients related to heart disease have surgical operation by expanding a blood vessel to treat the angiostenosis. So far most angioplasties have been performed using balloon-dilative stent made of stainless steel. Some researchers are studying the stent made of shape memory alloy (SMA) to operate the angioplasty more easily. and there are several papers which introduce the angioplasty using SMA. However, most of the analysis models for stents are constructed using solid elements. So much computing time is required to solve the analysis model. In this study, we suggest the SMA stent model using 1D truss element which is much faster than stent model using 3D solid element. To represent non-linear behavior of SMA, we apply 1D SMA constitutive equation of Lagoudas'. Pseudo-elastic behavior of stent structures is presented as a numerical example.

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Characteristics of Wave Propagation in an Unbounded Solid State Electron Plasma (무한고상전자프라즈마내에서의 전파전파특성)

  • Cho, Chul
    • 전기의세계
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    • v.22 no.3
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    • pp.35-48
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    • 1973
  • This paper deals with wave propagations in solid state electron plasmas from the view point of treating the plasma as a conducting fluid, and especially consideration is extended to the effect of diffusion on the permittivities and dispersion relations. The analysis is based on the conception of the self-consistent field approximation. It is shown for the cases of the specific physical configurations that the positions of the null elements in the permittivity tensors are not affected by the diffusion terms, and the diffusion effect appears only in the case of the space-charge wave. It is also shown that the magnitude of the real part of wave vector is in proportion to the 3/2nds power of the field in some regions.

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Forced Vibration Analysis of a Hollow Crankshaft by using Transfer Matrix Method and Finite Element Method (전달 행렬법과 유한요소법을 이용한 중공 크랭크축의 강제 진동 해석)

  • 김관주;최진욱
    • Transactions of the Korean Society of Automotive Engineers
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    • v.5 no.6
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    • pp.44-52
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    • 1997
  • As part of the effort to reduce the weight of powertrain, a hollow crankshaft has been designed. The mass reduction of the crankshaft changes the dynamic properties of the crankshaft such as moment of inertia, and torsional, bending stiffness. The purpose of this paper is to compare the dynamic behavior of the hollow crankshaft with that of the original, solid crankshaft. Global dynamic behavior of the crankshaft is analyzed bgy the transfer matrix method(TMM). The crankshaft has been modeled by 38 lumped mass and stiffness elements. The dynamic patameters of each lumped element are provided by Finite Element Method(FEM). The responses of the crankshaft from TMM are fed back as loading conditions to the Finite Element model to obtain dynamic stresses for critical areas of the crankshaft.

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Geometrically nonlinear analysis of planar beam and frame structures made of functionally graded material

  • Nguyen, Dinh-Kien;Gan, Buntara S.;Trinh, Thanh-Huong
    • Structural Engineering and Mechanics
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    • v.49 no.6
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    • pp.727-743
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    • 2014
  • Geometrically nonlinear analysis of planar beam and frame structures made of functionally graded material (FGM) by using the finite element method is presented. The material property of the structures is assumed to be graded in the thickness direction by a power law distribution. A nonlinear beam element based on Bernoulli beam theory, taking the shift of the neutral axis position into account, is formulated in the context of the co-rotational formulation. The nonlinear equilibrium equations are solved by using the incremental/iterative procedure in a combination with the arc-length control method. Numerical examples show that the formulated element is capable to give accurate results by using just several elements. The influence of the material inhomogeneity in the geometrically nonlinear behavior of the FGM beam and frame structures is examined and highlighted.

Performance analysis of composite piezoceramic actuator by assumed strain elements (가정 변형률 요소를 이용한 복합재 압전작동기의 작동특성해석)

  • 김영성;이상기;박훈철;윤광준
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2002.04a
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    • pp.461-469
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    • 2002
  • This paper deals with a fully coupled piezoelectric-mechanical assumed strain solid element that can be used for geometric and material nonlinear modeling of thin piezoelectric actuators. Since the assumed strain solid element can alleviate locking, the element is suitable for performance analysis of very thin actuators without locking. A finite element code is developed based on the finite element formulation and validated by solving typical numerical examples such as bimorph and unimorph beams. Using thecode, we have conducted performance analysis for LIPCA actuator. The estimated actuation displacement of LIPCA agrees well with experimental data under low prescribed voltage.

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Improvement of Flow Characteristics for Thin-Wall Injection Molding by Rapid Beating (급속 가열에 의한 박육 사출성형의 유동특성 개선)

  • Kim, Byung;Park, Keun
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.09a
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    • pp.9-12
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    • 2005
  • The rapid thermal response (RTR) molding is a novel process developed to raise the temperature of mold surface rapidly to the polymer melt temperature prior to the injection stage and then cool rapidly to the ejection temperature. The resulting filling process is achieved inside a hot mold cavity by prohibiting formation of frozen layer so as to enable thin wall injection molding without filing difficulty. The present work covers flow simulation of thin wall injection molding using the RTR molding process. In order to take into account the effects of thermal boundary conditions of the RTR mold, coupled analysis with transient heat transfer simulation is suggested and compared with conventional isothermal analysis. The proposed coupled simulation approach based on solid elements provides reliable thin wall flow estimation fur both the conventional molding and the RTR molding processes

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Collapse behaviour in reciprocal frame structures

  • Garavaglia, Elsa;Pizzigoni, Attilio;Sgambi, Luca;Basso, Noemi
    • Structural Engineering and Mechanics
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    • v.46 no.4
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    • pp.533-547
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    • 2013
  • "Reciprocal Frame" refers to a self-supporting grid structure used both for floor and roof. Using Finite Element Methods for non-linear solid mechanics and frictional-contact, this paper intends to analytically and numerically investigate the collapse behaviour of a reciprocal frame structure made of fibre-reinforced concrete. Considering a simple 3-beam structure, it has been investigated using a solid finite element model. Once defined the collapse behaviour of the simple structure, the analysis has been generalized using a concentrated plasticity finite element method. Results provided will be useful for studying generic reciprocal frame structures with several beams.

Axisymmetric thermomechanical analysis of transversely isotropic magneto thermoelastic solid due to time-harmonic sources

  • Lata, Parveen;Kaur, Iqbal
    • Coupled systems mechanics
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    • v.8 no.5
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    • pp.415-437
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    • 2019
  • The present research deals with two-dimensional axisymmetric deformation in transversely isotropic magneto thermoelastic solid with and without energy dissipation, with two temperature and time-harmonic source. The proposed model is helpful for finding the type of relations between mechanical and thermal fields as most of the structural elements of heavy industries are frequently related to mechanical and thermal stresses at a higher temperature. The Hankel transform has been used to find a solution to the problem. The displacement components, stress components, and temperature distribution with the horizontal distance in the physical domain are calculated numerically. The effect of time-harmonic source and two temperature is depicted graphically on the resulting quantities.