• 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.

• Structural Engineering and Mechanics
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• v.3 no.4
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• pp.383-390
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• 1995

A 2-D four-noded finite element which contains a ${\lambda}$ singularity is developed. The new element is compatible with quadratic standard isoparametric elements. The element is tested on two different examples. In the first example, an edge crack problem is analyzed using two different meshes and different integration orders. The second example is a crack perpendicular to the interface problem which is solved for different material properties and in turn different singularity order ${\lambda}$. The results of those examples illustrate the efficiency of the proposed element.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.2
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• pp.73-78
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• 1992

Numerical method by Abdi et al. for obtaining a stress singularity near a crack perpendicular to the interface between two elastic materials is reviewed. More efficient and simple method to obtain crack singularity by shifting a mid-side node of 8-node isoparametric element is presented. It is observed that the present analysis provides increased accuracy for the expression of the opening displacement and the determination of the optimal position of the mid-side node for a wide range of material properties.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.5
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• pp.164-171
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• 2006

Application of friction welding is increasing in the manufacturing process of machine elements in many industry fields. To establish a reasonable strength evaluation method and fracture criterion, it is necessary to analyze stress singularity under the residual stress condition on friction welded interface between dissimilar materials. In this paper, a method to establish fracture criterion on interface of friction welded dissimiliar materials was investigated by using the boundary element method BEM and static tensile testing. A quantitative fracture criterion for friction welded dissimilar materials is suggested by using stress singularity factor, $\Gamma$.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.11
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• pp.2277-2286
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• 2002

The application of bonded dissimilar materials to industries as automobiles, aircraft, rolling stocks, electronic devices and engineering structures is increasing gradually because these materials, compared to the homogeneous materials, have many advantages for material properties. In spite of such wide applications of bonded dissimilar materials, the evaluation method of quantitative strength considering the stress singularities for its bonded interface has not been established clearly. In this paper, the stress singularity for Bctors and the stress intensity factors were analyzed by boundary element method(BEM) for the scarf joints of Al/Epoxy with and without a crack, respectively. From static fracture experiments of the bonded scarf joints, a fracture criterion and a evaluation method of interface strength in bonded dissimilar materials were proposed and discussed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.769-772
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• 1997

In this study, By employing two dimensional(2-D) Boundary Element Method(BEM) stress analysis was carried to investigate stress distributions on the brazing joint of a Hardmetal and a HSS. Two model was proposed to analyze stress singularity in brazed interface. The stress results from the BEM were considered influence of the kind of materials , thickness of filled metal and length of vertical brazing adhesive. From those obtained results , the peak point of stress was founded in the lower part of two interface was made by brazing. As the thickness and length changed, the maximum stress tended to change in the peak point.

• Journal of the Microelectronics and Packaging Society
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• v.7 no.4
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• pp.31-35
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• 2000

The stress state developed in a thin adhesive layer bonded between the semiconductor chip and the leadframe and subjected to a shear loading is investigated. The boundary element method (BEM) is employed to investigate the behavior of interface stresses. Within the context of a linear elastic theory, a stress singularity of type $\gamma^{\lambda=1}$(0<1<1) exists at the point where the interface between one of the rigid adherends and the adhesive layer intersects the free surface. Such singularity might lead to edge crack or delamination.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.7
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• pp.171-176
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• 2003

In this study, stress analysis using Boundary Element Method (BEM) was carried to investigate stress distribution in the brazing joint between a Hardmetal and a HSS. The two models were proposed to analyze the stress singularity in the interfaces of the brazing joint. The material type, thickness of the filler metal and the length of the vertical brazing adhesive are considered in the BEM analysis. As results, the peak point of the stress is founded to be in the lower interface of the brazed joint. It should be noted that the maximum stress of the peak point is being affected by the thickness and length of the brazing joint.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.4
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• pp.59-67
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• 2006

Recently, application of friction welded SUH35/SUH3 is increasing in the manufacturing process of automotive engine valves For securing its reliability and a reasonable strength evaluation method, it is necessary to assess stress singularity under the residual stress condition on the friction welded interface between dissimilar materials. In this paper, strength evaluation method of friction welded materials was investigated by boundary element method and static tensile testing. An advanced method of quantitative strength evaluation for SUH35/SUH3 friction welded material is to be suggested by establishing fracture criterion by using stress singularity factors.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.10
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• pp.2398-2406
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• 1993

Abdi's numerical method(ref.13) for representing a stress singularity by shifting the mid-side nodes of isoparametric elements is reviewed. A simple technique to obtain the optimal position of the mid-side nodes in quadratic isoparametric finite element is presented. From this technique we can directly obtain the position of the side-nodes adjacent to the crack tip. It is also observed that the present technique provides good accuracy for the expression of the opening displacement and the determination of the mid-side nodes for more wide range of material properties than that obtained by Abdicant the finite element method is applied to determine stress intensity factors for pressurized crack perpendicular to and terminating at the interface of two bonded dissimilar materials. A proper definition for stress intensity factors of a crack perpendicular to bimaterial interface is provided. It is based upon a near-tip displacement solutions on the crack surface for interface crack between two dissimilar materials. Numerical testing is carried out with the eight-node and six-node elements. The results obtained are compared with the previous solutions.