• Composites Research
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• v.17 no.4
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• pp.68-73
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• 2004

An analytical study was conducted to characterize the fatigue crack growth behavior of pre-cracked aluminum plates repaired with asymmetric bonded composite patch. For single-sided repairs, due to the asymmetry and the presence of out-of$.$plane bending, crack front shape would become skewed curvilinear started from a uniform through-crack profile, as observed from Previous studies. Therefore, for the accurate investigation of fatigue behavior, it is necessary to predict the actual crack front evolution and take it into consideration in the analysis. In this study, the fatigue analysis of single-sided repairs considering crack front shape development was conducted by implementing three-dimensional successive finite element method coupled with linear elastic fracture mechanics (LEFM) concept, which enables the growing crack front to be directly traced and modeled in a step by step way. Through conducting present analysis technique, crack path of the patched plate as well as the fatigue life was evaluated with sufficient accuracy. The analytical predictions of both the crack front shape evolution and the fatigue life were in good agreement with the experimental observations.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.165-169
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• 2000

A simple method was suggested to calculate the stress intensity factor for a one-sided patched crack with finite thickness. To consider out-of-plane bending effect resulting from the load-path eccentricity, the spring constant as a function of the through-thickness coordinate z was calculated from the stress distribution in the un-cracked plate, ${\sigma}_{yy}(y=0,\;z)$, and the displacement for the representative single strip Joint, $u_y(y=0,\;z)$. The stress Intensity factors were obtained using Rose's asymptotic solution approach and compared with the finite element results. In short crack region, two results had a little difference. However, two results were almost same in long crack region. On the other hand, the stress intensity factor using plane stress assumption was more similar to finite element result than plane strain condition.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.241-245
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• 2004

An analytical study was conducted to characterize the fatigue crack growth behavior of pre-cracked aluminum plates repaired with asymmetric bonded composite patch. For single-sided repairs, due to the asymmetry and the presence of out-of-plane bending, crack front shape would become skewed curvilinear started from a uniform through-crack profile, as observed from previous studies. In this study, the fatigue analysis of single-sided repairs considering crack front shape development was conducted by implementing three-dimensional successive finite element method coupled with linear elastic fracture mechanics (LEFM) concept, which enables the growing crack front to be directly traced and modeled in a step by step way. Through conducting present analysis technique, crack path of the patched plate as well as the fatigue life was evaluated with sufficient accuracy. The analytical predictions of both the crack front shape evolution and the fatigue life were in good agreement with the experimental observations.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.5
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• pp.359-370
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• 2021

Duct slabs, which are used to build ventilation facilities in underground spaces with transverse ventilation system, need to secure fire resistance according to longitudinal and heavy vehicle traffic of tunnels. This study measured the temperature change at the construction joint of the precast fireproof duct slab which integrates fire resistance material and duct slab under the RWS fire scenario. As a result, it was confirmed that if there is no reinforcement of the construction joint, damage will occur in concrete inside the construction joint, leading to damage to the fireproofing layer. On the other hand, when one side of the construction joint was reinforced with fireproofing materials, it showed more than three times the fire resistance performance compared to when there was no reinforcement. At this time, cross-sectional losses of concrete and fireproofing layer were shown in blocks without reinforcement, but no damage was seen in the reinforced blocks.