• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.310-313
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• 2010

본 논문에서는 등가소성힌지길이 개념을 새롭게 개선하여 도입함하여 구조물의 거동특성을 평가하는 프로그램을 개발하였다. 시간의 경과 및 외부환경 변화와 더불어 발생 가능한 지하구조물의 변상은 해당 구조물의 구성재료 및 작용하는 외압의 형태 등에 의해 다르게 나타나게 된다. 즉, 장기적인 지반외력의 변화에 의해 콘크리트 구조체의 천단부에 큰 휨압축응력과 인장을력이 생기는데, 내측에는 압축이 생기고 외측에는 인장균열이 발생한다. 또한 측벽이나 어깨부에서는 인장응력과 전단응력에 의한 균열이 발생하기도 한다. 따라서 개발된 프로그램으로 균열발생단면에 대하여 축력, 휨모멘트, 균열폭을 서로 연관 지을 수 있게 될 뿐만 아니라 균열폭의 확장을 추적해 나갈 수 있다. 해석기법을 토대로 개발된 해석모듈을 이용하여, 본 해석 기법의 타당성에 대한 검증을 실시하였다. 검증을 위해서는 수평보구조와 터널구조에 대해 각각 해석을 수행하였다. 그 결과, 구조물 내에서의 균열의 진전이 점차적으로 확장되어 가는 것이 표현 가능한 것을 확인하였으며, 해석결과의 타당성을 확인하였다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.1 s.53
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• pp.115-124
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• 2009

In this study, a numerical analysis technique was newly developed to evaluate the damage propagation characteristics of concrete structures. To do this, numerical techniques are incorporated for the concrete members up to the compressive damage due to the bending compressive forces after the tensile crack based on the deformation mechanism. Especially, for the compressive damage stage after the tensile crack, the crack propagation process will be analyzed numerically using the concept of an equivalent plastic hinged length. Using this concept, it can be established that section forces, such as axial forces and the moment cracks takes place, can be related to the width of the crack making it possible to analyze the crack extension.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.6
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• pp.511-517
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• 2009

In this paper an finite element approach for the edge crack analysis of silicon-steel sheet during cold rolling is presented. Based on the damage mechanics, the proposed approach follows the analysis steps which are composed of damage initiation, damage evolution and fracture. Through those steps, we can find out the initiation instant of crack and resulting propagated length and shape of the crack. The material constants related to fracture is experimentally obtained by tension tests using standard sheet-type specimen and notched sheet-type specimen. To evaluate the prediction accuracy, we performed a pilot rolling test with a initially notched sheets. It is shown that the results obtained by the approach converged to the experimental one concerning about the direction and length of propagated crack. The capability of the proposed one is demonstrated through the application to the actual silicon-steel rolling mill.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.907-910
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• 2010

This study has developed a numerical analysis technique newly which can evaluate the damage propagation characteristics of civil infrastructures. To do this, numerical techniques are incorporated for the concrete members up to the compressive damage due to the bending compressive forces after the tensile crack based on the deformation mechanism. Especially, for the compressive damage stage after the tensile crack, the crack propagation process will be analyzed numerically using the concept of an equivalent plastic hinged length. Using this concept, we investigate the reasonability of the developed module by comparing commercial program for the tunnel structure. It can be established from this study that section forces, such as axial forces and the moment cracks takes place, can be related to the width of the crack making it possible to analyze the crack extension.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.12
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• pp.1619-1625
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• 2012

An electrical steel strip is commonly used as a core material in all types of electric transformers and motors. It is produced by a cold rolling process. In this paper, a damage-mechanics-based approach that predicts the edge fracture of an electrical steel strip during cold rolling is presented. We adopted the normal tensile stress criterion and the fracture energy method as a damage initiation criterion and a damage evolution scheme, respectively. We employed finite element analysis (FEA) to simulate crack initiation and propagation at the initial notch located at the edges of the strip. The material constants required in FEA were experimentally obtained by tensile tests using a standard and a notched sheet-type specimen. The results reveal that the edge crack was initiated at the entrance of the roll bite and that it rapidly evolved at the exit. The evolution length of the edge crack increased as the length of the initial notch as well as the front tension reel force of the strip increased.