• Computational Structural Engineering
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• v.9 no.4
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• pp.181-187
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• 1996

This paper concerns the singular thermal stresses at the interface corner between the elastic fiber and the viscoelastic matrix of a two-dimensional unidirectional laminate model induced during cooling from cure temperature down to room temperature. Time-domain boundary element method is employed to investigate the nature of residual thermal stresses at the interface. Numerical results show that very large stress gradients are present at the interface corner and such stress singularity might lead to local yielding or fiber-matrix debonding.

• Journal of Ocean Engineering and Technology
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• v.17 no.6
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• pp.72-76
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• 2003

This paper deals with the stress singularity developed in a polymer layer that is coated to a concrete surface, due to temperature change. The boundary element method is employed to investigate the behavior of interface stresses. The polymeric layer is assumed to be a linear viscoelastic material, and is thermorheologically simple. The order of the singularity is obtained, numerically, for a given viscoelastic model. Numerical results exhibit the relaxation of interface stresses, and large gradients are observed in the vicinity of the free surface. Results show that the stress singularity factor is relaxed with time, while the order of the singularity increases with time for the viscoelastic model.

• 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.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.174-179
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• 2004

The growth of the critical size bubble by diffusion process in viscoelastic medium was treated by an integral method for the concentration boundary layer adjacent to the bubble wall. In this study, we obtained a set of the first order time dependent equations to obtain bubble radius and gas pressure inside the bubble simultaneously. The calculated final cell sizes depending on the initial saturation pressure are in close agreement with the observed ones. The governing equations developed in this study may be used in polymer processing of microcellular foams.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.10a
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• pp.217-223
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• 1996

A structure's vibration characteristic is determined by modal property of the system. Through proper vibration analysis or experiments, the structure can be modified to reduce of vibration and noise. This paper is concerned with the natural frequency and modal loss factor of sandwich plates with viscoelastic core. The effects of shear and normal strain in the viscoelastic layer are investigated on modal properties, natural frequency and modal loss factor, by changing geometry parameter and viscoelastic material property of sandwich plates. The errors of modal parameters resulting from neglecting the extension or compression in the core material for simply supported(S-S-S-S) case are compared with those for clamped(C-C-C-C) boundary condition. Finite difference method(FDM) is utilized as numerical analysis technique of square sandwich plates for fixed boundary conditions. In order to reduce computation time and increase accuracy, improved finite difference expression with fourth order truncation error was used.

• 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.

• Bulletin of the Korean Mathematical Society
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• v.54 no.4
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• pp.1457-1470
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• 2017

In this paper, we consider the stabilization of the viscoelastic wave equation with variable coefficients in a bounded domain with smooth boundary, subject to linear dissipative internal feedback with a delay. Our stabilization result is mainly based on the use of the Riemannian geometry methods and Lyapunov functional techniques.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.146-152
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• 2002

In this study, the singular thermal stresses induced during cooling down from high temperature to room temperature have been analyzed for the viscoelastic thin layer. The time domain boundary element method has been employed to investigate the behavor of stresses for the whole interface. Within the context of a linear viscoelastic theory, a stress singularity exists at the point where the interface between the elastic substrate and the viscoelastic thin layer intersects the free surface.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.389-394
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• 2003

In this study, the stress singularity factors generated during cooling down from high curing temperature to room temperature have been analyzed for the viscoelastic thin film. The time domain boundary element method has been employed to investigate the behavior of stresses for the whole interface. Within the context of a linear viscoelastic theory, a stress singularity exists at the point where the interface between the elastic substrate and the viscoelastic thin film intersects the free surface.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.11a
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• pp.137-142
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• 2002

This paper deals with the stress singularity induced at the interface corner between the elastic substrate and the viscoelastic thin film as the polymeric film absorbs moisture from the ambient environment. The boundary element method is employed to investigate the behavior of Interface stresses. The order of the singularity is obtained numerically for a given viscoelastic model. It is shown that the stress singularity factor is relaxed with time, while the order of the singularity increases with time for the viscoelastic model considered.