• Title/Summary/Keyword: Viscoelastic Condition

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EXPONENTIAL DECAY FOR THE SOLUTION OF THE VISCOELASTIC KIRCHHOFF TYPE EQUATION WITH MEMORY CONDITION AT THE BOUNDARY

  • Kim, Daewook
    • East Asian mathematical journal
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    • v.34 no.1
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    • pp.69-84
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    • 2018
  • In this paper, we study the viscoelastic Kirchhoff type equation with a nonlinear source for each independent kernels h and g with respect to Volterra terms. Under the smallness condition with respect to Kirchhoff coefficient and the relaxation function and other assumptions, we prove the uniform decay rate of the Kirchhoff type energy.

Simulation of Explosion Using the Ideal Viscoelastic Object Yield Condition (이상적인 점탄성체 항복 조건을 이용한 폭발 시뮬레이션)

  • Sung, Su-Kyung;Kim, Gyeong-Su;Shin, Byeong-Seok
    • Journal of Korea Game Society
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    • v.14 no.6
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    • pp.49-58
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    • 2014
  • In particle-based fluid simulation, the yield stress is required for the deformation of the viscoelastic material like gel. von Mises's yield condition has been proposed to implement deformation of viscoelastic objects, but did not express the explosion. Furthermore, von Mises's yield condition is hard to approximate. We propose an ideal yield condition for viscoelastic object that reference from Tresca's yield condition. Unlike conventional particle-based simulation approximate the external power by the deformed length of the object, this paper is approximate the external power by area of the object. We check up that explosion was realistic when a viscoelastic object is compressed under the ideal yield condition.

STABILIZATION FOR THE VISCOELASTIC KIRCHHOFF TYPE EQUATION WITH A NONLINEAR SOURCE

  • Kim, Daewook
    • East Asian mathematical journal
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    • v.32 no.1
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    • pp.117-128
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    • 2016
  • In this paper, we study the viscoelastic Kirchhoff type equation with a nonlinear source $$u^{{\prime}{\prime}}-M(x,t,{\parallel}{\bigtriangledown}u(t){\parallel}^2){\bigtriangleup}u+{\int}_0^th(t-{\tau})div[a(x){\bigtriangledown}u({\tau})]d{\tau}+{\mid}u{\mid}^{\gamma}u=0$$. Under the smallness condition with respect to Kirchhoff coefficient and the relaxation function and other assumptions, we prove the uniform decay rate of the Kirchhoff type energy.

Estimation of Viscoelastic Properties of Trabecular Bone Using An Inverse Method (역추기법을 이용한 해면골의 점탄성 특성 해석)

  • Kang, Shin-Ill;Lee, Won-Hee;Hong, Jung-Hwa
    • Journal of Biomedical Engineering Research
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    • v.18 no.3
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    • pp.211-216
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    • 1997
  • An inverse method with regularization has been developed to determine the viscoelastic properties of trabecular bone. A series of stress relaxation experiments were performed under the condition of uniaxial compression stress state. Optimization has been formulated within the framework of nonlinear least-squares and a modified Gauss-Newton method with a zeroth-order regularization technique. The stress relaxation behavior of trabecular bone was analyzed using a standard viscoelastic model. The present study clearly shows that trabecular bone exhibits typical viscoelastic stress relaxation behavior, and the obtained material parameters well represent the viscoelastic behavior of trabecular bone.

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Cost-Effectiveness Evaluation of the Structure with Viscoelastic Dampers (점탄성감쇠기를 설치한 구조물의 비용효율성 평가)

  • 고현무;함대기;조상열
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2001.04a
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    • pp.387-393
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    • 2001
  • Installing vibration control devices in the structure rises as a solution instead of increasing structural strength considering construction cost. Especially, viscoelastic dampers show excellent vibration control performance at low cost and are easy to install in existing structures compared with other control devices. Therefore, cost-effectiveness of structure with viscoelastic dampers needs to be evaluated. Previous cost-effectiveness evaluation method for the seismically isolated structure(Koh et al., 1999;2000)is applied on the building structure with viscoelastic dampers, which combines optimal design and cost-effectiveness evaluation for seismically isolated structures based on minimum life-cycle cost concept. Input ground motion is modeled in the form of spectral density function to take into account acceleration and site coefficients. Damping of the viscoelastic damper is considered by modal strain energy method. Stiffness of shear building and shear area of viscoelastic damper are adopted as design variables for optimization. For the estimation of failure probability, transfer function of the structure with viscoelastic damper for spectral analysis is derived from the equation of motion. Results reveal that cost-effectiveness of the structure with viscoelastic dampers is relatively high in how seismic region and stiff soil condition.

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Numerical analysis on heat transfer due to buoyancy force of viscoelastic fluid (점탄성 유체의 부력에 의한 열전달 수치해석)

  • Ahn S. T.;Sohn C. H.;Shin S. H.
    • Journal of computational fluids engineering
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    • v.4 no.2
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    • pp.9-16
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    • 1999
  • The present study investigates flow character and heat transfer behaviors of viscoelastic non-Newtonian fluid in a 2:1 rectangular duct. An axially-constant heat flux on bottom wall and peripherally constant temperature boundary condition(H1) was adopted. The Reiner-Rivlin fluid model is used as the normal stress model for the viscoelastic fluid and temperature-dependent viscosity model is adopted. The present results show a signifiant change of the main flow field which causes a large heat transfer enhancement. This phenomena can be explained by the combined effect of buoyancy, temperature-dependent viscosity and viscoelastic property on the flow.

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A Study on the Injection Flow with Viscoelastic Effect (점탄성 효과를 가진 사출 유동에 관한 연구)

  • Jeon, Eon-Chan;Park, Jung-Woo;Kim, Soo-Yong;Lee, Chul-Jang;Ahn, Kwang-Woo
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.7 no.3
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    • pp.25-29
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    • 2008
  • In this paper, we design internal space in plunger-type low pressure vacuum injection molding machine from numerical study. And we study characteristic of viscoelastic flow for searching injection molding condition. Then the flow analysis was performed using the CAE S/W. The result shows optimal value of nozzle and hole in injection chamber. And we investigated qualitatively relationship between injection pressure and injection mass flow with variable shear rate

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ASYMPTIOTIC BEHAVIOR FOR THE VISCOELASTIC KIRCHHOFF TYPE EQUATION WITH AN INTERNAL TIME-VARYING DELAY TERM

  • Kim, Daewook
    • East Asian mathematical journal
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    • v.32 no.3
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    • pp.399-412
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    • 2016
  • In this paper, we study the viscoelastic Kirchhoff type equation with the following nonlinear source and time-varying delay $$u_{tt}-M(x,t,{\parallel}{\nabla}u(t){\parallel}^2){\Delta}u+{\int_{0}^{t}}h(t-{\tau})div[a(x){\nabla}u({\tau})]d{\tau}\\+{\parallel}u{\parallel}^{\gamma}u+{\mu}_1u_t(x,t)+{\mu}_2u_t(x,t-s(t))=0.$$ Under the smallness condition with respect to Kirchhoff coefficient and the relaxation function and other assumptions, we prove the uniform decay rate of the Kirchhoff type energy.

Testing for Identification of Dynamic Properties of Viscoelastic Material Subject to Large Static Deformation (정적 대변형을 받고 있는 점탄성 재료의 동적 물성치 규명 시험)

  • 이완술;이호정;조지현;김진성;윤성기;김광준
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.2
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    • pp.132-143
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    • 2003
  • Viscoelastic components for vibration isolation or shock absorption in automobiles, machines and buildings are often subject to a high level of static deformation. From the dynamic design point of view, it is requisite to predict dynamic complex stiffness of viscoelastic components accurately and efficiently. To this end, a systematic procedure for complex modulus measurement of the viscoelastic material under large static deformation is often required in the industrial fields. In this paper, dynamic test conditions and procedures for the viscoelastic material under small oscillatory load superimposed on large static deformation are discussed. Various standard test methods are investigated in order to select an adequate test methodology. The influence of fixed boundary condition in the compression tests upon complex stiffness are investigated and an effective correction technique is proposed. Then the uniaxial tension and compression tests are performed and its results are compared with analysis results from conventional constitutive models.

Vibration and Damping Characteristics of Viscoelastically Damped Sandwich Plates (점탄성층이 샌드위치된 복합적층판의 진동감쇠 특성)

  • 김재호;박태학;신현정
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.9
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    • pp.2252-2263
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    • 1993
  • The purpose of this study is to verify the vibration and damping characteristics of elastic-viscoelastic-elastic structures, theoretically and experimentally. The forth-order differential equations of motion are derived for the transverse vibration of three-layered plates with viscoelastic core layer. The equations consider both transverse displacements of the constraining layer and the bare base plate as variable and account for the effect of the transverse normal strain and the shear strain of viscoelastic core layer on the vibration of the plates. Finite difference analysis of the equations and experimental measurements are performed on the three-layered plates of completely free boundary condition. Comparative investigations on the theory and the results of direct frequency analysis of NASTRAN are carried out on the same structures.