• Title/Summary/Keyword: higher order terms

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The Nonlinear Analysis and Modeling of the ER Fluid Damper Using Higher Order Spectrum (고차 주파수 스펙트럼을 이용한 ER 유체 댐퍼의 비선형 특성 해석 및 모델링 연구)

  • Kim, Dong-Hyun;Joung, Tae-Whee;Joh, Joongseon
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.1 s.178
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    • pp.105-112
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    • 2006
  • The nonlinear damping force model is made to identify the properties of the ER (electro-rheological) fluid suspension damper. The instrumentation is carried out to measure the damping force of the ER damper. The higher order spectral analysis method is used to investigate the nonlinear frequency coupling phenomena with the damping force signal according to the sinusoidal excitation of the damper. The distinctive higher order nonlinear characteristics are observed. The nonlinear damping force model, which has the higher order velocity terms, is proposed with the result of higher order spectrum analysis. The higher order terms coefficients, which vary according to the strength of the electric field, are calculated using the least square method.

The Analysis of Smart Plate Using Enhanced First Shear Deformation Theory (개선된 일차전단변형이론을 이용한 지능구조평판의 거동해석)

  • Oh, Jin-Ho;Kim, Heung-Su;Rhee, Seung-Yun;Cho, Maeng-Hyo
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2007.04a
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    • pp.663-668
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    • 2007
  • An enhanced first shear deformation theory for composite plate is developed. The detailed process is as follows. Firstly, the theory is formulated by modifying higher order zigzag theory. That is, the higher order theory is separated into the warping function representing the higher order terms and lower order terms. Secondly, the relationships between higher order zig-zag field and averaged first shear deformation field based on the Reissner-Mindlin's plate theory are derived. Lastly, the effective shear modulus is calculated by minimizing error between higher order energy and first order energy. Then the governing equation of FSDT is solved by substituting shear modulus into effective shear modulus. The recovery processing with the nodal unknown obtained from governing equation is performed. The accuracy of the present proposed theory is demonstrated through numerical examples. The proposed method will serve as a powerful tool in the prediction of laminated composite plate.

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Higher Order Wall Boundary Conditions for Incompressible Flow Simulations

  • Nishida Hidetoshi
    • 한국전산유체공학회:학술대회논문집
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    • 2003.10a
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    • pp.61-62
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    • 2003
  • In this paper, the new higher order wall boundary conditions are proposed for solving the incompressible flows. The square driven cavity flows are simulated by using the variable order method of lines with the present wall boundary conditions. The variable order method of lines is constructed by the spatial discretization, i.e., the variable order proper convective scheme for convective terms and the modified differential quadrature method for diffusive terms, and time integration. The 2nd, 4th, and 6th order solutions are presented and these results show this higher order boundary conditions are very promising for the incompressible flow simulations.

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Effect of higher order terms of Maclaurin expansion in nonlinear analysis of the Bernoulli beam by single finite element

  • Zahrai, Seyed Mehdi;Mortezagholi, Mohamad Hosein;Mirsalehi, Maryam
    • Structural Engineering and Mechanics
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    • v.58 no.6
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    • pp.949-966
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    • 2016
  • The second order analysis taking place due to non-linear behavior of the structures under the mechanical and geometric factors through implementing exact and approximate methods is an indispensible issue in the analysis of such structures. Among the exact methods is the slope-deflection method that due to its simplicity and efficiency of its relationships has always been in consideration. By solving the differential equations of the modified slope-deflection method in which the effect of axial compressive force is considered, the stiffness matrix including trigonometric entries would be obtained. The complexity of computations with trigonometric functions causes replacement with their Maclaurin expansion. In most cases only the first two terms of this expansion are used but to obtain more accurate results, more elements are needed. In this paper, the effect of utilizing higher order terms of Maclaurin expansion on reducing the number of required elements and attaining more rapid convergence with less error is investigated for the Bernoulli beam with various boundary conditions. The results indicate that when using only one element along the beam length, utilizing higher order terms in Maclaurin expansion would reduce the relative error in determining the critical buckling load and kinematic parameters in the second order analysis.

Comparative dynamic studies of thick laminated composite shells based on higher-order theories

  • Ganapathi, M.;Patel, B.P.;Pawargi, D.S.;Patel, H.G.
    • Structural Engineering and Mechanics
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    • v.13 no.6
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    • pp.695-711
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    • 2002
  • Here, the dynamic response characteristics of thick cross-ply laminated composite cylindrical shells are studied using a higher-order displacement model. The formulation accounts for the nonlinear variation of the in-plane and transverse displacements through the thickness, and abrupt discontinuity in slope of the in-plane displacements at any interface. The effect of inplane and rotary inertia terms is included. The analysis is carried out using finite element approach. The influences of various terms in the higher-order displacement field on the free vibrations, and transient dynamic response characteristics of cylindrical composite shells subjected to thermal and mechanical loads are analyzed.

GENERAL CONVERGENCE ANALYSIS OF THE LVCMS ALGORITHM (LVCMS 알고리즘에 대한 일반적인 수렴 특성 분석)

  • Nam, Seung-Hyon;Kim, Yong-Hoh
    • The Journal of Natural Sciences
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    • v.8 no.2
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    • pp.63-67
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    • 1996
  • Adaptive algorithms based on the higher order error criterion such as the LVCMS and the LMF show performance degradation if input signal contains additive noise with a heavier-tailed density. Conventional analysis often neglects higher order terms in the recursion and my not suit for prediction exact behavior of these higher order algorithms. This paper presents a new convergence analysis which contains all the higher order term in the recursion. The analysis shows that the higher order terms, which are often neglected, dose not affect the upper bound on the step size but the misadjustment. However, the effect decreases sharply proportional to the square of the step size.

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Capillary-Gravity waves on the Interface of a Two Layer Fluid-Derivation of K-dV Equation with Higher Order Terms

  • Choi, Jeongwhan
    • Journal of the Chungcheong Mathematical Society
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    • v.5 no.1
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    • pp.151-157
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    • 1992
  • The objective of this paper is to study two dimensional waves on the interface between two immiscible, invicid and incompressible fluid bounded by two rigid varing boundaries when gravity and surface tension appear. By using unfied asymptotic method, a K-dV equation with higher order terms from which many model equations for the fluid domain can be obtained, is derived.

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A numerical study of the second-order wave excitation of ship springing by a higher-order boundary element method

  • Shao, Yan-Lin;Faltinsen, Odd M.
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.6 no.4
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    • pp.1000-1013
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    • 2014
  • This paper presents some of the efforts by the authors towards numerical prediction of springing of ships. A time-domain Higher Order Boundary Element Method (HOBEM) based on cubic shape function is first presented to solve a complete second-order problem in terms of wave steepness and ship motions in a consistent manner. In order to avoid high order derivatives on the body surfaces, e.g. mj-terms, a new formulation of the Boundary Value Problem in a body-fixed coordinate system has been proposed instead of traditional formulation in inertial coordinate system. The local steady flow effects on the unsteady waves are taken into account. Double-body flow is used as the basis flow which is an appropriate approximation for ships with moderate forward speed. This numerical model was used to estimate the complete second order wave excitation of springing of a displacement ship at constant forward speeds.