• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.2
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• pp.67-75
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• 2006

In this paper, the compensation of ultrasonic scattering on interface crack depending on thickness variations of A1/Epoxy bonded dissimilar components was applied to improve measuring accuracy by using ultrasonic attenuation coefficient. The optimum conditions of theoretical value and experimental measuring accuracy by the ultrasonic method in A1/Epoxy bonded dissimilar components have been investigated. From the experimental results, the measurement method of interfacial crack lengths by using ultrasonic attenuation coefficient was proposed and discussed. After the ultrasonic scattering compensation depending on thickness variations of bonded dissimilar components was carried out, the measuring accuracy of interfacial crack length was improved by 5%.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.25-30
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• 2004

In this paper, the compensation of interfacial scatter due to adhesive layer and adherend thickness ratio variation was applied to improve measuring precision by calculating ultrasonic attenuation coefficient in the Al/Epoxy dissimilar bonded components. The optimum condition of theoretical value and experimental measuring accuracy by the ultrasonic method in the Al/Epoxy dissimilar bonded components have been investigated. From the experimental results, we proposed a measurement method of the interfacial crack lengths by the ultrasonic attenuation coefficient and discussed it.

• International Journal of Automotive Technology
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• v.6 no.3
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• pp.293-303
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• 2005

Bonded dissimilar materials are being increasingly used in automobiles, aircraft, rolling stocks, electronic devices and engineering structures. Bonded dissimilar materials have several material advantages over homogeneous materials such as high strength, high reliability, light weight and vibration reduction. Due to their increased use it is necessary to understand how these materials behave under stress conditions. One important area is the analysis of the stress intensity factors for interface cracks emanating from circular holes in bonded dissimilar materials. In this study, the bonded scarf joint is selected for analysis using a model which has comprehensive mixed-mode components. The stress intensity factors were determined by using the boundary element method (BEM) on the interface cracks. Variations of scarf angles and crack lengths emanating from a centered circular hole and an edged semicircular hole in the Al/Epoxy bonded scarf joints of dissimilar materials are computed. From these results, the stress intensity factor calculations are verified. In addition, the relationship between scarf angle variation and the effect by crack length and holes are discussed.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.2
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• pp.182-189
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• 2004

The application of adhesively bonded components is increasing in various industries such as automobile, aircraft, IC packages, and soldering techniques. In spite of such wide application in adhesively bonded components, nondestructive test techniques applying to adhesively bonded components have not been clearly established yet. In this paper, characteristics of ultrasonic test on interfaces of adhesively bonded components have been investigated by calculating transmission coefficient theoretically and experimentally. From the experimental results, the optimum conditions to establish frequencies for adhesively bonded homogeneous and dissimilar components are 4∼6 MHz and 2∼4 MHz, respectively.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.346-351
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• 2003

In this paper, an evaluation method of fracture toughness on interface cracks has been investigated under various mixed-mode conditions of the bonded scarf joints. Two types of the bonded scarf joints with an interface crack were prepared to analyze the stress intensity factors using boundary element method(BEM) and to perform the fracture toughness test. From the results of fracture toughness experiments and BEM analysis, an evaluation method of fracture toughness on interface cracks in the bonded components of dissimilar materials has been proposed and discussed.

• 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.

• 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.