• Title/Summary/Keyword: viscoelastic adhesive layer

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Viscoelastic Stress Analysis of Adhesive-bonded Cylindrical by FEM (유한요소법을 이용한 원통체의 점탄성 응력 해석)

  • Park, Sung-Jin
    • Journal of the Society of Disaster Information
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    • v.15 no.2
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    • pp.259-267
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    • 2019
  • Purpose: In this paper adhesive-bonded cylindrical lap joints are analyzed by assuming that the adherends are elastic and the adhesive is linearly viscoelastic. Method: The distribution of the stresses in the adhensive is evaluated using the Finite Element Method. Nuverical examples for identical and different adherends bonded through a four parameter viscoelastic solid adhesive are illustrated. Results: The stress distribution in the adhesive layer with respect to time is shown. The stress distribution in the adhesive layer with respect to time is shown. The results are also shown that adherend thickness and elastic modulus give effect on the normalized stress. Conclusion: In this study, the stress distribution of the adhesive layer of the wrapped cylindrical body considering the viscoelasticity of the adhesive layer was numerically analyzed by using a four - element elastomer model.

Boundary Element Analysis of Stress Singularity at the Interface Corner of Viscoelastic Adhesive Layer Bonded Between Rigid Adherends (강체모재들을 결합하고 있는 점탄성 접착재층의 계면모서리에서 발생하는 응력특이성의 경제요소해석)

  • 이상순;박준수
    • Computational Structural Engineering
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    • v.10 no.2
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    • pp.131-138
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    • 1997
  • This paper concerns the stress singularity at the interface corner of the viscoelastic adhesive layer bonded between rigid adherends, subjected to a uniform transverse tensile strain. The characteristic equation is derived in the Laplace transformed space, following Williams, and the transformed characteristic equation is inverted analytically into real time space for the viscoelastic model considered here. The order of the singularity is obtained numerically. The time-domain boundary element method is employed to investigate the nature of stresses along the interface. Numerical results show that the order of the singularity increases with time while the free-edge stress intensity factors are relaxed with time.

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Analysis of Residual Stresses Induced during Adhesion Process of Chip and Leadframe (칩과 리드페임의 접착과정에서 발생하는 잔류 응력 해석)

  • 이상순
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.13 no.1
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    • pp.97-103
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    • 2000
  • This paper deals with residual stresses induced at the viscoelastic adhesive layer between the semiconductor chip and the leadframe during adhesion process. The adhesive layer has been assumed to be“thermorheologically simple”. The time-domain boundary element method(BEM) has been employed to investigate the behavior of interface stresses. Numerical results show that very large stress gradients are present at the interface corner and such singularity might lead to local yielding or edge delamination.

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Relaxation of Singular Stress in Adhesively Bonded Joint at High Temperature

  • Lee, Sang Soon
    • Journal of the Semiconductor & Display Technology
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    • v.17 no.1
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    • pp.35-39
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    • 2018
  • This paper deals with the relaxation of singular stresses developed in an epoxy adhesive at high temperature. The interface stresses are analyzed using BEM. The adhesive employed in this study is an epoxy which can be cured at room temperature. The adhesive is assumed to be linearly viscoelastic. First, the distribution of the interface stresses developed in the adhesive layer under the uniform tensile stress has been calculated. The singular stress has been observed near the interface corner. Such singular stresses near the interface corner may cause epoxy layer separated from adherent. Second, the interfacial thermal stress has been investigated. The uniform temperature rise can relieve the stress level developed in the adhesive layer under the external loading, which can be viewed as an advantage of thermal loading. It is also obvious that temperature rise reduces the bonding strength of the adhesive layer. Experimental evaluation is required to assess a trade-off between the advantageous and deleterious effects of temperature.

Vibration and damping characteristics of the masonry wall strengthened with bonded fibre composite patch with viscoelastic adhesive layer

  • Laib, Salaheddine;Meftah, Sid Ahmed;Youzera, Hadj;Ziane, Noureddine;Tounsi, Abdelouahed
    • Computers and Concrete
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    • v.27 no.3
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    • pp.253-268
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    • 2021
  • The present paper treats the free vibration problem of the masonry wall strengthened with thin composite plate by viscoelastic adhesive layer. For this goal two steps are considered in the analytical solution. In the first one, an efficient homogenisation procedure is given to provide the anisotropic properties of the masonry wall. The second one is dedicated to purpose simplified mathematical models related to both in-plane and out-of-plane vibration problems. In these models, the higher order shear theories (HSDT's) are employed for a more rigours description of the shear deformation trough the masonry wall and the composite sheet. Ritz's method is deployed as solution strategy in order to get the natural frequencies and their corresponding loss factors. The obtained results are validated with the finite element method (FEM) and then, a parametric study is undertaken for different kinds of masonry walls strengthened with composite sheets.

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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A Study for Creep Effect of the Interfacial Adhesive Layer on the Behavior of Concrete with CFRP (탄소섬유시트로 보강된 콘크리트 구조물 경계면 재료의 크리프 영향 해석)

  • Park, Yong Deuk;Shin, Seung Kyo;Kang, Suk Hwa;Lim, Yun Mook
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.30 no.3A
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    • pp.221-228
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    • 2010
  • External bonding of carbon fiber reinforced polymer (CFRP) sheets has been widely accepted as a popular method for strengthening of deteriorated RC structures. The long-term behavior of CFRP-strengthened RC structure is often affected by that of the interface between CFRP sheets and concrete. This study aims at applying a viscoelastic model to describe the creep behaviour of the adhesive layer bonding CFRP sheet to concrete, the CFRP-concrete interface. Reviews of available models on concrete creep behavior have been first carried out and then new FE analysis model is proposed. The proposed FE analysis model based on the maxwell model has been verified by previous experimental results. It is shown that the creep effect of interfacial adhesive layer is very important on the long-term behavior of concrete structures strengthened with CFRP.

Studies on the Vibration Controllability of Smart Structure Depending on the Interfacial Adhesion Properties of Composite Materials (복합재료내의 계면 접착 특성에 따른 지능형 구조물의 진동제어에 관한 연구)

  • 한상보;박종만;차진훈
    • Journal of KSNVE
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    • v.8 no.6
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    • pp.1093-1102
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    • 1998
  • The success of controllability of smart structures depends on the quality of the bonding along the interface between the main structure and the attached sensing and acuating elements. Generally, the analysis procedures neglect the effect of the interfacial bond layer or assume that this bond layer behaves like viscoelastic material. Three different bond layers. two modified epoxy adhesives, and one isocyanate adhesive were prepared for their toughness and moduli. Bond layer of the chosen adhesive provides an almost perfect bonding condition between the composite structure and the PZT while bended significantly like arrow-shape. The perfect bonding condition is tested by considering various material properties of the bond layers. and based on this perfect bonding condition, the effects of the interfacial bond layer on the dynamic behavior and controllability of the test structure is experimentally studied. Once the perfect bonding condition is achieved. dynamic effects of the bond layer itself on the dynamic characteristics of the main structure is negligible. but the contribution of the attached PZT elements on the stiffness of the multi-layered structure becomes significant when the thickness of the bond layer increased.

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Dynamic design of piezoelectric structures for an efficient tactile feedback of index finger on touch screen (검지의 효율적 화면접촉감응을 위한 압전-구조물계의 동적설계)

  • Park, Young-Min;Kim, Kwang-Joon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2009.04a
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    • pp.280-281
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    • 2009
  • Piezoelectric vibrators can be good replacements of electric motors to excite touch screen of a mobile device owing to small volume and low power consumption. One problem to be solved yet for real application is larger excitation force or moment than available currently. More efficient excitation by a piezoelectric vibrator could be achieved by operating at one of resonance frequencies of the system, which must also be as close as possible to frequency range where index finger is most sensitive and increasing transmission force or moment at that frequency. In this study, dynamic models are derived for the piezoelectric exciter and an adhesive viscoelastic layer, which connect the exciter to the screen. The adhesive layer is modeled as distributed stiffness by considering its geometric shape to relative to the piezoelectric exciter. Then, equations of motion for the piezoelectric exciter and the adhesive layer are derived using Hamilton's principle. Based on this model, dynamic characteristics of the exciter will be designed to maximize the force or moment transmitted onto the screen structure.

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Waterproofing Materials According to the External Environment of Non-exposed Waterproofing Materials for Underground Structures Performance Change Requirement (지하 구조물용 비노출형 방수재의 외부환경에 따른 방수재의 성능 변화 요구)

  • Jung, Suk-Joo;Song, Je-Young;Won, Seong-Jae;Oh, Sang-Keun
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2020.06a
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    • pp.85-86
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    • 2020
  • In securing durability of underground structure non-exposed waterproof materials, the company aims to improve durability of waterproof materials by studying more realistic weather conditions than KS standards and developers' durability standards. Analyzing the actual climate data in Korea and the temperature of the basement layer, it is a waterproofing sheet method, a self-adhesive sheet method in which a film and a compound, which are currently widely used as underground water-proofing, and a self-adhesive waterproofing sheet method, etc. We would like to present the guidelines necessary to prevent the temperature situation and waterproof defects that are ideal for setting the endurance conditions later.

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