• Title/Summary/Keyword: 점탄성 해석

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Viscoelastic Analysis for Behavior of Edge Cracks at the Bonding Interface of Semiconductor Chip (반도체 칩 접착 계면에 존재하는 모서리 균열 거동에 대한 점탄성 해석)

  • 이상순
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.14 no.3
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    • pp.309-315
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    • 2001
  • The Stress intensity factors for edge cracks located at the bonding interface between the elastic semiconductor chip and the viscoelastic adhesive layer have been investigated. Such cracks might be generated due to stress singularity in the vicinity of the free surface. The domain boundary element method(BEM) has been employed to investigate the behavior of interface stresses. The overall stress intensity factor for the case of a small interfacial edge crack has been computed. The magnitude of stress intensity factors decrease with time due to viscoelastic relaxation.

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혼합형 고체 추진제의 비선형 구성방정식 개발 동향

  • 정규동;윤성기
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 1996.05a
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    • pp.85-93
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    • 1996
  • 비선형 해석의 중요성이 증가하고 있는 혼합형 고체 추진제의 비선형거동중 재료비선형에 대한 거시적/미시적 현상을 설명하고, 그 주요한 원인으로서 Mullin 효과와 결합제/충전미립자 사이의 접착분리(Dewetting)를 주로 고찰하였다. 이를 응용한 지금까지의 비선형 구성방정식의 개발동향을 검토하여 비교하였으며 최근에 제시되고 있는 손상변수를 분석하였다. 여러 변형률 크기에 대한 응력이완 모듈러스 실험을 통하여 변형률 크기가 손상변수로서 적합하지 않음을 보였으며, 변형률 크기에 따라 모듈러스의 저하가 크기 때문에 비선형 점탄성 해석이 중요한 문제임을 제시하였다.

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Bending and Vibration Analysis of Elastic and Viscoelastic Laminated Composite Structures using an Improved Higher-order Theory (개선된 고차이론을 이용한 복합재료 적층구조물의 탄성 및 점탄성적 휨, 진동해석)

  • Han, Sung Cheon;Yoo, Yong Min;Park, Dae Yong;Chang, Suk Yoon
    • Journal of Korean Society of Steel Construction
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    • v.14 no.1
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    • pp.1-12
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    • 2002
  • To obtain more accurate responses of laminated composite structures, the effect of transverse shear deformation, transverse normal strain/stress and a nonlinear variation of in-plane displacements with respect to the thickness coordinate need to be considered in the analysis. The improved higher-order theory is used to determine the deflections and natural frequencies of laminated composite structures. A quasi-elastic method is used for the solution of viscoelastic analysis of the laminated composite plates and sandwiches. Solutions of simply-supported laminated composite plates and sandwiches are obtained and the results are compared with those by the 3D elasticity theory and other theories. The improved theory proposed in this paper is shown to predict the deflections and natural frequencies more accurately than all other theories.

Thermal Viscoelastic Analysis of Plastic Part Considering Residual Stress (온도 및 잔류응력을 고려한 플라스틱 부품의 점탄성 해석)

  • Moon, H.I.;Kim, H.Y.;Choi, C.W.;Jeong, K.S.
    • Transactions of Materials Processing
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    • v.17 no.7
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    • pp.496-500
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    • 2008
  • Plastics is commonly used in consumer electronics because of it is high strength per unit mass and good productivity. But plastic parts are usually distorted after injection molding due to the residual stress after filling, packing, cooling process, and etc. And plastic material is to be deteriorated according to various temperature conditions and operating time, which can be characterized by stress relaxation and creep. The viscoelastic behavior of plastic materials in time domain can be expressed by the Prony series of the commercial code, ABAQUS. In the paper, the process to predict the post deformation under cyclic thermal loadings was suggested. The process was applied to the real panel, and the deformation predicted by the analysis was compared with that of real test, which showed the possibility of applying the suggested process to predict the post deformation of plastic product under thermal loadings.

A Viscoelastic Analysis for Spent Pressurized Water Reactor Nuclear Fuel Disposal Canister (가압경수로 고준위폐기물 처분용기에 대한 점탄성 해석)

  • 권영주;하준용
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2003.05a
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    • pp.327-330
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    • 2003
  • In this paper, a viscoelastic structural analysis for the spent pressurized water reactor(PWR) nuclear fuel disposal canister is carried out to predict the collapse of the canister while the canister is stored in a deep repository for long time. There may exist some subterranean heat in a deep repository while the nuclear fuel disposal canister is stored for long time. Then, a time-dependent viscoelastic structural deformation may occur in the canister due to the subterrnean heat Hence, the viscoelastic stress variation according to time should be computed to predict the structural strength of the canister. A viscoelastic material model is adopted. Analysis results show that even though some subterrnean heat may exist for quite a long time, the canister structure still endures stresses below the yield strength of the canister. Hence, some subterranean heat cannot seriously affect the structural strength of the canister.

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Viscoelastic Analysis of Stress Intensity Factor for Interface Edge Crack in a Unidirectional Liminate (단일방향 복합재료의 공유면에 존재하는 계면 모서리균열의 점탄성 해석)

  • 이상순;김범식
    • Computational Structural Engineering
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    • v.10 no.1
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    • pp.129-134
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    • 1997
  • Interfacial stress singularity in a unidirectional two-dimensional laminate model consisting of an elastic fiber and a viscoelastic matrix has been investigated using the time-domain boundary element method. First, the interfacial singular stresses between the fiber and the matrix of a unidirectional laminate subjected to a uniform transverse tensile strain have been investigated near the free surface, but without any defect or any edge crack. Such a stress singularity might lead to fiber-matrix debonding or interfacial edge cracks. Then, the overall stress intensity factor for the case of a small interfacial edge crack of length a has been computed.

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Linear Viscoelastic Identification (선형 점탄성 해석)

  • Kwon, Mi Kyung;Cho, Kwang Soo
    • Textile Science and Engineering
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    • v.58 no.1
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    • pp.1-16
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    • 2021
  • With an increase in the awareness of polymer viscoelasticity, several researchers in the textile industry have conducted rheological experiments to investigate the polymeric materials they deal with. However, the experimental results can be interpreted meaningfully when the polymeric materials are processed and analyzed based on viscoelastic theory. This review first describes the fundamental theories of linear viscoelasticity. Moreover, it provides various examples of linear viscoelastic studies on polydisperse polymer melts, polymer solutions, polymer blends, and reacting systems. The types of experiments depend on the measured viscoelastic functions. Viscoelastic functions are mathematically interconvertible within a linear viscoelastic range. However, numerical data processing is necessary to practically apply theoretical relations to experimental results. Here, we review several useful numerical methods and algorithms. We hope this review could be a helpful guide for researchers analyzing the viscoelasticity of textile materials.

Thermal Viscoelastic Analysis of Plastic Part Considering Residual Stress (온도 및 잔류응력을 고려한 플라스틱 부품의 점탄성 해석)

  • Moon, H.I.;Kim, H.Y.;Choi, C.W.;Jeong, K.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2008.05a
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    • pp.288-292
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    • 2008
  • Plastics is commonly used in consumer electronics because of it is high strength per unit mass and good productivity. But plastic parts are usually distorted after injection molding due to the residual stress after filling, packing, cooling process, and etc. And plastic material is to be deteriorated according to various temperature conditions and operating time, which can be characterized by stress relaxation and creep. The viscoelastic behaviour of plastic materials in time domain can be expressed by the Prony series of the commercial code, ABAQUS. In the paper, the process to predict the post deformation under cyclic thermal loadings was suggested. The process was applied to the real panel, and the deformation predicted by the analysis was compared with that of real test, which showed the possibility of applying the suggested process to predict the post deformation of plastic product under thermal loadings.

  • PDF