• 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.28 no.8 s.227
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• pp.1229-1236
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• 2004

The specimen materials used in this research are isotropic epoxy resins. The static photoelastic experiment was applied to them. And then the specimens used in photoelastic experiment were fractured under static load. The static photoelastic experimental hybrid method was introduced and its validity had been assured. Crack propagation criterion used the stress components, which are considered the higher order terms, obtained from the static photoelastic experimental hybrid method was introduced and it was applied to the minimum strain energy density criterion, the maximum tangential stress criterion and mode mixity. Comparing the actual initial angle of crack propagation with the theoretical initial angle of crack propagation obtained from the above failure criterions, the validities of the above two criterions are assured and the optimal distance (r) from the crack-tip is 0.01mm in order to get the initial angle of crack propagation of isotropic epoxy resin.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.11
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• pp.1799-1806
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• 2004

The static photoelastic experiment was applied to orthotropic materials. And then the specimens used in photoelastic experiment were fractured under static load. The static photoelastic experimental hybrid method for orthotropic material was introduced and its validity had been assured. Crack propagation criterion used the stress components, which are considered the higher order terms, obtained from the static photoelastic experimental hybrid method was introduced and it was applied to the minimum strain energy density criterion, the maximum tangential stress criterion and mode mixity. Comparing the actual initial angle of crack propagation with the theoretical initial angle of crack propagation obtained from the above failure criterions, the validities of the above two criterions are assured and the optimal distance (${\gamma}$) from the crack-tip is 0.01mm in order to get the initial angle of crack propagation of orthotropic material(C.F.E.C.).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.8
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• pp.1273-1280
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• 2003

In this paper, transparent dynamic photoelastic experimental hybrid method for propagating cracks in orthotropic material was developed. Using transparent dynamic photoelastic experimental hybrid method, we can obtain stress intensity factor and separate the stress components from only isochromatic fringe patterns without using isoclinics. When crack is propagated with constant velocity, the contours of stress components in the vicinity of crack tip in orthotropic material are similar to those of isotropic material or orthotropic material with stationary crack under the static load. Dynamic stress intensity factors are decreased as crack growths. It was certified that the dynamic photoelastic experimental hybrid method was very useful for the analysis of the dynamic fracture mechanics.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.3
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• pp.434-442
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• 2001

When the interfacial crack of two dissimilar isotropic 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 bimaterial is introduced. It is assured that stress components and dynamic photoelastic hybrid method developed in this research are valid. Separating method of stress component is introduced from only dynamic photoelastic fringe patterns. Crack propagating velocity of interfacial crack is 80∼85% (in case of aluminum, 24.3∼25.9%) of Rayleigh wave velocity of epoxy resin. The near-field stress components of crack-tip are similar with those of pure isotropic material under static or dynamic loading, but very near-field stress components of crack-tip are different from those.

• 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.

• 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.