• Title, Summary, Keyword: homogeneous extension

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Extension of Rational Interpolation Functions for FE Analysis of Rotating Beams (회전하는 보의 유한요소해석을 위한 유리형상함수의 확장)

  • Kim, Yong-Woo;Jeong, Jae-Ho
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.573-578
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    • 2009
  • Starting from the rotating beam finite element in which the interpolating shape functions satisfies the governing static homogeneous differential equation of Euler-Bernoulli rotating beams, we derived new shape functions that satisfies the governing differential equation which contains the terms of hub radius and setting angle. The shape functions are rational functions which depend on hub radius, setting angle, rotational speed and element position. Numerical results for uniform and tapered cantilever beams with and without hub radius and setting angle are compared with the available results. It is shown that the present element offers an accurate method for solving the free vibration problems of rotating beam.

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GAS-LIQUID TWO-PHASE HOMOGENEOUS MODEL FOR CAVITATING FLOW -Part II. HIGH SPEED FLOW PHENOMENA IN GAS-LIQUID TWO-PHASE MEDIA (캐비테이션 유동해석을 위한 기- 2상 국소균질 모델 -제2보: 기-액 2상 매체중의 고속유동현상)

  • Shin, B.R.;Park, S.;Rhee, S.H.
    • Journal of computational fluids engineering
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    • v.19 no.3
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    • pp.91-97
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    • 2014
  • A high resolution numerical method aimed at solving cavitating flow was proposed and applied to gas-liquid two-phase shock tube problem with arbitrary void fraction. The present method with compressibility effects employs a finite-difference 4th-order Runge-Kutta method and Roe's flux difference splitting approximation with the MUSCL TVD scheme. The Jacobian matrix from the inviscid flux of constitute equation is diagonalized analytically and the speed of sound for the two-phase media is derived by eigenvalues. So that the present method is appropriate for the extension of high order upwind schemes based on the characteristic theory. By this method, a Riemann problem for Euler equations of one dimensional shock tube was computed. Numerical results of high speed flow phenomena such as detailed observations of shock and expansion wave propagations through the gas-liquid two-phase media and some data related to computational efficiency are made. Comparisons of predicted results and solutions at isothermal condition are provided and discussed.

Transient Response of a Crack in a Functionally Graded Piezoelectric Strip between Two Dissimilar Piezoelectric Strip (두 개의 서로 다른 압전재료층 사이의 기능경사압전재료 접합층 내부 균열에 대한 과도응답 해석)

  • Shin, Jeong Woo;Lee, Young-Shin;Kim, Sung Joon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.206-213
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    • 2013
  • Transient response of a crack in a functionally graded piezoelectric material (FGPM) interface layer between two dissimilar homogeneous piezoelectric layers under anti-plane shear is analyzed using integral transform approaches. The properties of the FGPM layer vary continuously along the thickness. Laplace and Fourier transforms are used to reduce the problem to two sets of dual integral equations, which are then expressed to the Fredholm integral equations of the second kind. Numerical values on the dynamic energy release rate (DERR) are presented for the FGPM to show the effects on electric loading, gradient of the material properties, and thickness of the layers. Computed results yield following conclusions: (a) the DERR increases with the increase of the gradient of the material properties of the FGPM layer; (b) certain direction and magnitude of the electric impact loading impedes crack extension; (c) increase of the thickness of the FGPM layer and the homogeneous piezoelectric layer which has larger material properties than those of the crack plane are beneficial to increase of the resistance of transient fracture of the FGPM layer.

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Influence of thickness and incisal extension of indirect veneers on the biomechanical behavior of maxillary canine teeth

  • Costa, Victoria Luswarghi Souza;Tribst, Joao Paulo Mendes;Uemura, Eduardo Shigueyuki;de Morais, Dayana Campanelli;Borges, Alexandre Luiz Souto
    • Restorative Dentistry and Endodontics
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    • v.43 no.4
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    • pp.48.1-48.13
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    • 2018
  • Objectives: To analyze the influence of thickness and incisal extension of indirect veneers on the stress and strain generated in maxillary canine teeth. Materials and Methods: A 3-dimensional maxillary canine model was validated with an in vitro strain gauge and exported to computer-assisted engineering software. Materials were considered homogeneous, isotropic, and elastic. Each canine tooth was then subjected to a 0.3 and 0.8 mm reduction on the facial surface, in preparations with and without incisal covering, and restored with a lithium disilicate veneer. A 50 N load was applied at $45^{\circ}$ to the long axis of the tooth, on the incisal third of the palatal surface of the crown. Results: The results showed a mean of $218.16{\mu}strain$ of stress in the in vitro experiment, and $210.63{\mu}strain$ in finite element analysis (FEA). The stress concentration on prepared teeth was higher at the palatal root surface, with a mean value of 11.02 MPa and varying less than 3% between the preparation designs. The veneers concentrated higher stresses at the incisal third of the facial surface, with a mean of 3.88 MPa and a 40% increase in less-thick veneers. The incisal cover generated a new stress concentration area, with values over 48.18 MPa. Conclusions: The mathematical model for a maxillary canine tooth was validated using FEA. The thickness (0.3 or 0.8 mm) and the incisal covering showed no difference for the tooth structure. However, the incisal covering was harmful for the veneer, of which the greatest thickness was beneficial.

Three Dimensional Vortex Behavior of LEX Delta Wing by Dynamic Stereo PIV (Dynamic Stereo PIV에 의한 델타형 날개에서의 3차원 와류 유동에 관한 연구)

  • Lee Hyun;Kim Mi-Young;Choi Jang-Woon;Choi Min-Seon;Lee Young-Ho
    • 한국가시화정보학회:학술대회논문집
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    • pp.39-42
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    • 2003
  • Leading edge extension(LEX) in a highly swept shape applied to a delta wing features the modern air-fighters. The LEX vortices generated upon the upper surface of the wing at high angle of attack enhance the lift force of the delta wing by way of increased negative suction pressure over the surfaces. The present 3-D stereo PIV includes the Identification of 2-D cross-correlation equation, stereo matching of 2-D velocity vectors of two cameras, accurate calculation of 3-D velocity vectors by homogeneous coordinate system, removal of error vectors by a statistical method followed by a continuity equation criterion and so on. A delta wing model with or without LEX was immersed in a circulating water channel. Two high-resolution, high-speed digital cameras$(1280pixel\times1024pixel)$ were used to allow the time-resolved animation work. The present dynamic stereo PIV represents the complicated vortex behavior, especially, in terms of time-dependent characteristics of the vortices at given measuring sections. Quantities such as three velocity vector components, vorticity and other flow information can be easily visualized via the 3D time-resolved post-processing to make the easy understanding of the LEX effect or vortex emerging and collapse which are important phenomena occurring in the field of delta wing aerodynamics.

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A Study on the Unsteady Flow Characteristics of a Delta Wing by 3-D Stereo PIV (3-D Stereo PIV에 의한 비정상 델타윙 유동특성에 대한 연구)

  • Kim, Beom-Seok;Lee, Hyun;Kim, Jeong-Hwan;Lee, Young-Ho
    • Proceedings of the KSME Conference
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    • pp.1672-1677
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    • 2004
  • Leading edge extension(LEX) in a highly swept shape applied to a delta wing features the modem air-fighters. The LEX vortices generated upon the upper surface of the wing at high angle of attack enhance the lift force of the delta wing by way of increased negative suction pressure over the surfaces. The present 3-D stereo PIV includes the Identification of 2-D cross-correlation equation, stereo matching of 2-D velocity vectors of two cameras, accurate calculation of 3-D velocity vectors by homogeneous coordinate system, removal of error vectors by a statistical method followed by a continuity equation criterion and so on. A delta wing model with or without LEX was immersed in a circulating water channel. Two high-resolution, high-speed digital cameras($1280pixel{\times}1024pixel$) were used to allow the time-resolved animation work. The present dynamic stereo PIV represents the complicated vortex behavior, especially, in terms of time-dependent characteristics of the vortices at given measuring sections. Quantities such as three velocity vector components, vorticity and other flow information can be easily visualized via the 3D time-resolved post-processing to make the easy understanding of the LEX effect or vortex emerging and collapse which are important phenomena occurring in the field of delta wing aerodynamics.

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Japanese Design and Technological Development after the Mid 16th Century (일본의 기술발전과 디자인 -16세기 이후 서구문물의 도입과 일본 디자인의 발전-)

  • 채승진
    • Archives of design research
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    • v.13 no.2
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    • pp.81-86
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    • 2000
  • From the ancient civilization, Japanese have maintained a homogeneous domestic culture while they have constantly received external ideas. They have received many conflicting and contradictory ideas and phenomena and surprisingly, they blend them successfully into their own culture. For them, the series of impacts from other civilizations have dissolved each equivalent individual elements for their successive culture. The introduction of Portuguese arquebus in the mid 16th century was a monumental event of Japanese technological development based on military initiatives. In terms of the Japanese import of western civilization from the time onward, the Meiji restoration could be explained the extension of the process modernization. Modern Japanese design is a unique case created through the close relationship between industry and cultural traditions. Such a role of traditional values and an alliance between political decision and economic program in post war years show two-fold implications

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Performance and Emission Characteristics of Compression Ignition Gasoline Engine (압축점화 가솔린기관의 성능 및 배기특성)

  • Kim, Hong-Sung;Kim, Mun-Heon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.7
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    • pp.1007-1014
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    • 2003
  • This work deals with a controlled auto-ignition (CAI) single cylinder gasoline engine, focusing on the extension of operating conditions. The fuel is injected indirectly into electrically heated inlet air flow. In order to keep a homogeneous air-fuel mixing, the fuel injector is water-cooled by a specially designed coolant passage. Investigated are the engine performance and emission characteristics under the wide range of operating conditions such as 32 to 63 in the air-fuel ratio, 1000 to 1800 rpm in the engine speed, and 150 to 18$0^{\circ}C$ in the inlet air temperature. The compression ignition gasoline engine can be achieved that the ultra lean-burn with self-ignition of gasoline fuel by heating inlet air. For example. the allowable lean limit of air-fuel ratio is extended until 63 at engine speed of 1000 rpm and inlet air temperature of 17$0^{\circ}C$. It can be achieved that the emission concentrations of carbon monoxide, hydrocarbons and nitrogen oxide had been significantly reduced by CAI combustion compared with conventional spark ignition engine.

Synthesis of 2,4-Dienoic Acid Derivatives by Palladium Catalyzed Homogeneous Reaction (팔라듐 촉매 균일계 반응을 이용한 2,4-디엔산 유도체의 합성)

  • Jin Il Kim
    • Journal of the Korean Chemical Society
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    • v.27 no.6
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    • pp.441-448
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    • 1983
  • A wide variety of vinylic bromides such as (Z)-1-bromopropene, 1-bromo-2-methylpropene, 2-bromo-3-methyl-2-butene, (E)-ethyl 2-methyl-3-bromo-2-propenoate, 1-bromo-cyclohexene has been found to react with ethyl acrylate, ethyl 3-butenoate, allyl cyanide, (E)-ethyl crotonate, ethyl 4-pentenoate, methyl 10-undecenoate and methyl methacrylate in the presence of triethylamine and a palladium acetate-triorthotolylphosphine catalyst. In general, 2,4-dienoic acid derivatives were obtained in good yield and stereochemistry of the products was determined. Using this method, four, five and eleven carbon-carbon extension with ethyl 3-butenoate, ethyl 4-pentenoate and methyl 10-undecenoate was also possible.

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A SPECTRAL LINE SURVEY FROM 159.7 TO 164.7 GHZ TOWARD ORION-KL: THE DATA

  • LEE CHANG WON;CHO SE-HYUNG
    • Journal of The Korean Astronomical Society
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    • v.35 no.4
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    • pp.187-196
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    • 2002
  • A spectral line survey is performed from 159.7 to 164.7 GHz toward Orion-KL, as an extension of our previous line survey from 138.3 to 150.7 GHz with the same 14 m radio telescope of Taeduk Radio Astronomy Observatory. Typical system temperatures were 260 - 1000 K to achieve a sensitivity of about 0.02 - 0.04 K in TA unit. A total of 63 line spectra are detected in this survey. Among them, 54 lines lines are found to be the first detections towards an astronomical source and only 9 spectral lines have been previously identified from other observations. Forty-eight of 54 lines are believed to be from the known transitions of the known molecules, while 6 lines are 'unidentified'. All detected lines are found to be from a total of 10 molecular species and their isotopic variants. The molecular species with most numerous detected transitions are $HCOOCH_3$ (22), followed by $CH_3OCH_3$ (7), $C_2H_5CN$ (7), and $SO_2$ (6). The LTE rotation diagram analysis using all homogeneous data with those from previous survey gives more reliable determination of physical quantities. The derived values of the rotation temperatures and column densities for $HCOOCH_3$, $CH_3OCH_3$, and $SO_2$ are are 75 $\~$ 197 K and $1.5 {\~}18 {\times} 10^{15}\;cm^{-2}$, respectively.