• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.7
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• pp.1055-1063
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• 2001

When the interfacial crack of isotropic/orthotropic bi-materials is propagated with constant velocity along the interface, stress and displacement components are derived in this research. The dynamic photoelastic experimental hybrid method for the bimaterial is introduced. It is assured that stress components and dynamic photoelastic hybrid developed in this research are valid. Separating method of stress components is introduced from only dynamic photoelastic fringe patterns. Crack propagating velocity of interfacial crack is 69∼71% of Rayleigh wave velocity of epoxy resin. The near-field stress components of bonded interface of bimaterial are similar with those of pure isotopic material and two dissimilar isotropic bimaterials under static or dynamic loading, but very near-field stress components of bonded interface of bimaterial are different from those.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1216-1221
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• 2003

The specimen materials used in this research is bimaterial. The static photoelastic experiment was applied to them. And then the specimens used in photoelastic experiment were fractured under static load. The static photoelastic hybrid method was introduced and it's validity had been assured. The static photoelastic hybrid method was applied to the Minimum Strain Energy Density Criterion, the Maximum Tangential Stress Criterion and Mode Mixity. Crack propagation criterion by the static photoelastic hybrid method was introduced and it was applied to the above various failure theories. Comparing the experimental initial angle of crack propagation with the theoretical initial angle of crack propagation from the various failure criterions. And then the optimal crack propagation criterion was suggested and it's validity was assured.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.12
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• pp.1200-1207
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• 2007

An experimental test is presented for photoelastic stress analysis around a crack tip in tensile loaded plate. The hybrid method coupling photoelastsic fringe inputs calculated by finite element method and complex variable formulations involving conformal mappings and analytical continuity is used to calculate full-field stress around the crack tip in uniaxially loaded, finite width tensile plate. In order to accurately compare calculated fringes with experimental ones, both actual and regenerated photoelastic fringe patterns are two times multiplied and sharpened by digital image processing. Regenerated fringes by hybrid method are quite comparable to actual fringes. The experimental results indicate that Mode I stress intensity factor analyzed by the hybrid method are accurate within three percent compared with ones obtained by empirical equation and finite element analysis.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.379-380
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• 2007

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.11
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• pp.1776-1785
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• 2004

In this research, the relationships between static bimaterial constant and dynamic oscillation index are studied. It was certified that static bimaterial constant has the same form equation as the dynamic oscillation index. Bimaterial constant and oscillation index are increased with the increment of Young's modulus ratio and approached to the some value. Isochromatic fringe patterns are slanted to the left side with increment of bimaterial constants and oscillation index. Though patterns of stress components in above the crack surface are similar to each other, their magnitudes are different a little. In the ahead of crack tip, there are big differences in the isochromatic fringe patterns and their magnitudes. The influence of bimaterial with Young's modulus ratio is bigger in the propagation crack than in the stationary crack.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.12
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• pp.1897-1905
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• 2004

In many part of machines or structures that made of bimaterial bonded with two dissimilar materials, most failures occur at their interface. Therefore, the accurate analysis of fracture characteristics and the evaluation of mechanical strength for interfacial crack are essential when we design those structures. In this research, stress and displacement components in the vicinity of stationary interfacial crack tip in the two dissimilar isotropic bimaterials are established. Hereafter, the stress components established in this research can be applied to the photoelastic hybrid method which can be used to analyze the fracture behavior of the two dissimilar isotropic bimaterials.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.228-233
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• 2008

The reflection type photoelastic experiment can be used more effectively than the transparent type photoelastic experiment in industrial fields. However, the reflection type photoelastic experiment for orthotropic material has not been studied. Therefore, the reflection type photoelastic experimental hybrid method for the fracture mechanics of orthotropic material was developed in this research. Comparing the results obtained from this method with those from the hybrid method for isotropic material about the same isotropic specimen, the validity of this method was verified. And then, the reflection type photoelastic experiment for orthotropic material was applied to the orthotropic plates with a central crack of the various inclined angle. Using this hybrid method for the orthotropic material, it is able to obtain stress intensity factors and separate stress components at the vicinity of the crack-tip in orthotropic plates from only the isochromatic fringe patterns of isotropic coating material.