• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.5 no.2
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• pp.215-222
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• 2015

This paper presents the measurement of stress intensity factors of inclined cracks by use of photoelasticity. The distributions of isochromatics near a crack tip of the specimen loaded by uniaxially tensile load are used for analysis. Accuracy and reliability is enhanced by twice multiplying and sharpening the measured isochromatics using digital image processing. Photoelastic results are compared with those obtained by finite element method. Good agreement between them shows that the photoelastic analysis is reliable.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.1
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• pp.27-33
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• 2012

Photoelasticity is a technique of experimental methods and has been widely used in various domains of engineering to determine the stress distribution of structures. Without complicated mathematical formulation, this technique can conveniently provide a fairly accurate whole-field stress analysis for a mechanical structure. Here, stress distribution around an inclined crack tip of finite-width plate is studied by 8-step phase-shifting method. This method is a kind of photoelastic phase-shifting techniques and can be used for the determination of the phase values of isochromatics and isoclinics. According to stress-optic law, the stress distribution could be obtained from fringe patterns. The results obtained by polariscope arrangement combined with 8-step method and ABAQUS FEM simulations are compared with each other. Good agreement between them shows that 8-step phase-shifting method is reliable and can be used for determination of stress by experiment.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.217-220
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• 2008

A modified FRP-concrete composite deck applicable to cable stayed bridge with long girder-to-girder span is proposed, and its design and economical efficiency are presented. The existing FRP-concrete composite deck has low section stiffness due to adoption of GFRP panel with low elastic modulus, which arrives at difficulty in meet of serviceability limit such as deck deflection. So a new-type FRP-concrete composite deck, named precast FRP-concrete deck, is developed by extensioning concrete at the both ends of FRP-concrete composite deck, which brings the effect of reduction of net span length of deck. Compared to the existing FRP-concrete composite deck this modified deck has the advantage of increasing span length but slightly increases self weight. For this type of deck the section optimization is carried out for the cases of simply supported on girder and composite to girder. The optimized deck was applied to cable stayed bridge with a center span length of 540m, and as a result it is verified that PFC deck can be applied efficiently to cable stayed bridge due to reduction of quantity of upper structure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.238-246
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• 2022

This paper summarizes the development and evaluation of the reinforcement details of CFRP plates to improve the bending performance of wooden beams. In this study, the reinforcing technology using high-strength bolts for the end of beam were developed as reinforcement details for reinforcing wooden beams with CFRP plates by EBM method. In order to evaluate the bending performance, a bending test was conducted for the specimens with details of reinforcement such as the EBM method and the NSM method. From the experimental results, the EBM specimens without end restraints had both the CFRP plate attachment failure and the splitting failure of the wood. In the load-displacement curve, the non-reinforced specimens exhibited linear elastic behavior and then brittle fracture after the maximum load. The maximum load of the specimens reinforced by the EBM method increased by 31.5~63.0% compared to the non-reinforced specimens, and the maximum load according to the end restraints of the high-strength bolts increased by 24.0%. Based on the reinforcement amount of the same CFRP plate, EBM reinforcement was 2.67 times larger in maximum load increase rate than NSM reinforcement.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.2
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• pp.148-154
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• 2014

Photoelasticity is a useful technique for obtaining the differences and directions of principal stresses in a model. In conventional photoelasticity, the photoelastic parameters are measured manually point by point. Identifying and measuring photoelastic data is time-consuming and requires skill. The fringe phase shifting method was recently developed and has been found to be convenient for measuring and analyzing fringe data in photo-mechanics. This paper presents an experimental study on the stress distribution along a horizontal line that passes the central point of a rhombus plate made of Photoflex (i.e., type of urethane rubber). The isoclinic fringe and/or principal stress direction is constant on this horizontal line, so a four-bucket phase shifting method can be applied. The method requires four photoelastic fringes that are obtained from a circular polariscope by rotating the analyzer at $0^{\circ}C$, $45^{\circ}C$, $90^{\circ}C$ and $135^{\circ}C$. Experimental measurements using the method were quantitatively compared with the results from FEM analysis; the results from the two methods showed comparable agreement.

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.291-296
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• 1998

노내에서 지지격자 스프링의 잔류 탄성변위는 시간(연소도)에 따라 변하게 된다. 이는 격자판의 중성자 조사에 의한 길이방향의 성장으로 지지격자 셀 크기의 증가와 피복관의 크리프에 의한 직경의 감소 및 중성자 조사에 의한 지지격자 스프링력의 이완으로 인한 것이다. 만일 지지격자 스프링의 거동이 변하여 연료봉을 탄성적으로 지지하지 못할 경우 이것은 연료봉의 유체에 의한 진동을 가속시키게 되며, 연료봉과 지지격자 스프링이나 딤플간의 반복적인 고주기의 충격하중은 연료봉의 지지부와 봉간(grid-to-rod)의 프레팅 마모의 원인이 될 수 있다. 따라서 시간에 따라 변하는 변수들의 영향을 고려한 지지격자 스프링의 잔류 탄성변위를 예측할 수 있는 방법론을 정립하여 새로운 지지격자체의 개발시 건전한 연료봉의 지지거동을 평가할 수 있는 도구로 활용하고자 하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.727-734
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• 2006

Although a limited number of experimental investigations and finite element analyses revealed that a curved web panel in practical design has a considerable reserve strength after the elastic buckling as a straight girder web panel, the current Guide Specifications for Horizontally Curved Steel Girder Highway Bridges (AASHTO, 2003) do not consider the postbuckling strength in the ultimate shear strength due to lack of a comprehensive study. In this study, the ultimate shear strength behavior of horizontally curved steel web panels was investigated through nonlinear finite element analysis and experimental test. It was found that curved web panels used in practical designs are able to develop the postbuckling strength that is equivalent to that of straight girder web panels having the same dimensional and material properties.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.3
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• pp.295-300
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• 1985

본 논문에서는 Dhir의 이론에 따라서 Mapping함수로 고차다항식을 사용하여 여러가지 하중상태에 따른 최적형상을 연구하고 Mapping함수에 포함되어 있는 계수가 응력집중 및 형상변화에 미치는 영향을 검토하며 광탄성 실험을 통하여 이론의 타당성 을 입증하고자 하였다.

• Proceedings of the KSEEG Conference
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• 2005.04a
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• pp.309-313
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• 2005

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.839-840
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• 2010