테이퍼 캔틸레버 원형강관 균열보의 모드특성 추정

이종원,김상렬,김봉기,Lee, Jong Won,Kim, Sang Ryul,Kim, Bong Ki 한국전산구조공학회 2014 한국전산구조공학회논문집 Vol.27 No.5

본 연구에서는 테이퍼 보에 대한 미분방정식의 일반해에 캔틸레버 보의 경계조건을 적용하여 모드특성을 추정한다. 또한, 휨을 받는 테이퍼 원형강관 캔틸레버 보에 발생하는 관통균열을 모델링하기 위하여 에너지 방법을 이용하여 균열보에 대한 보 길이방향 휨강성을 구한 후 이를 이용하여 테이퍼 원형강관 캔틸레버 균열보에 대한 고유주파수와 모드형상을 추정한다. 보 길이에 따른 균열보의 휨강성 변화는 기존 연구에서 밝혀진 현상과 유사하게 합리적인 양상을 보였으며, 유도한 휨강성을 적용하여 산정한 균열보의 고유주파수는 균열 크기가 증가할수록 감소함을 확인하였고, 모드형상은 균열발생에 의해 변화함을 알 수 있었다. 연구결과는 향후 테이퍼 원형강관 캔틸레버 보 형태의 타워 구조물에 대한 진동기반 균열탐지에 활용될 수 있을 것으로 판단된다. Modal properties for tapered cantilever pipe-type beam is identified by applying the boundary conditions to a general solution for tapered beam. A bending stiffness for cracked beam is constructed based on an energy method for tapered cantilever thin-walled pipe, which has a through-the-thickness crack, subjected to bending. Then the natural frequencies and mode shapes of a tapered cantilever thin-walled cracked pipe are identified. It can be found that the phenomenon of the bending stiffness distribution along the beam length of the cracked beam is quite reasonable, the natural frequencies are decreased as the crack sizes are increased, and the mode shapes are changed due to the crack. This results may be used to the vibration-based crack identification for the tapered cantilever pipe-type tower structures.

접착두께와 초기균열의 크기가 두꺼운 접착제로 연결된 이중 캔틸레버 보의 응력거동에 미치는 영향

엔달류아베바우몰라 ( Endalew A Molla ),우경식 ( Kyeongsik Woo ),김성보 ( Sung Bo Kim ) 충북대학교 건설기술연구소 2019 建設技術論文集 Vol.38 No.1

이중 캔틸레버 보는 복합재료의 파괴인성을 측정하는데 사용되는 표준시험 시편의 하나로, 그 응력거동은 초기균열 길이, 적층판과 접착제의 두께 및 물성치 등 다양한 요소에 영향을 받는다. 본 논문에서는 접착제로 연결된 탄소/에폭지 적층판 이중 캔틸레버 보의 응력거동을 수치적으로 연구하였다. 연구결과 균열선단 근처의 박리응력은 초기균열길이가 증가함에 따라서 증가하였다. 또한 접착제의 두께가 감소할수록 박리응력은 균열선단에서는 증가하지만 여기에서 멀어지면 반대로 감소하는 것으로 나타나 파손의 시작은 접착제의 두께가 감소할수록 빨리 발생할 것으로 예상되었다. Double Cantilever Beam (DCB) test is one of the standard tests which are used to measure the toughness of composite materials. The stress and failure behavior of DCB is affected by many factors such as initial crack length, adherend and adhesive thicknesses, composite stacking orientation angles and material property variations. In this paper, the effect of initial crack length and adhesive thickness variation was studied considering the peeling stress behavior of DCB near the crack tip. The elastic analysis of DCB was performed using two-dimensional finite element model in Abaqus/CAE. From the results, it was observed that the peeling stress near the crack tip increased as the initial crack length decreased but the relationship between the same stress and adhesive thickness was observed inconsistent. However, the maximum peeling stress increased as the considered parameters decreased.

테이퍼 원형강관 캔틸레버 보의 결함탐지기법

이종원(Lee, Jong-Won) 대한건축학회 2015 大韓建築學會論文集 : 構造系 Vol.31 No.2

A crack identification method using an equivalent bending stiffness for cracked beam and committee of neural networks is presented. Modal properties of tapered cantilever pipe-type beam is identified by applying the boundary conditions to a general solution for tapered beam. A bending stiffness for cracked beam based on an energy method is used to identify natural frequencies and mode shapes of tapered cantilever thin-walled pipe, which has a through-the-thickness crack, subjected to bending. The identified modal properties of the cracked beam are used in constructing training patterns of neural networks. Then crack location and size are identified using a committee of the neural networks. Crack detection was carried out for an example beam using the proposed method, and the identified crack locations and sizes agree reasonably well with the exact values.

배경셀의 수와 관련한 무요소법을 이용한 캔틸레버 보의 정적해석

이창계,이상진 대한건축학회지회연합회 2008 대한건축학회지회연합회 학술발표대회논문집 Vol.2008 No.1

A meshless method based on the radial point interpolation method(RPIM) is used to analyze cantilever beam. Meshless methods have been considered is a very attractive as new computational method since it does not need mesh generation in analysis procedure. Especially, RPIM, using radial basis function(RBF), has an advantage that do not consider the essential boundary condition. In order to demonstrate the accuracy of the adopted meshless method, numerical examples are tackled with multiple elastic moduli and the different number of background cell. Numerical results are compared with the reference solution produced by finite element analysis program FEAP.

테이퍼 원형강관 캔틸레버 보의 결함탐지기법

이종원,Lee, Jong-Won 大韓建築學會 2015 大韓建築學會論文集 : 構造系 Vol.31 No.2

A crack identification method using an equivalent bending stiffness for cracked beam and committee of neural networks is presented. Modal properties of tapered cantilever pipe-type beam is identified by applying the boundary conditions to a general solution for tapered beam. A bending stiffness for cracked beam based on an energy method is used to identify natural frequencies and mode shapes of tapered cantilever thin-walled pipe, which has a through-the-thickness crack, subjected to bending. The identified modal properties of the cracked beam are used in constructing training patterns of neural networks. Then crack location and size are identified using a committee of the neural networks. Crack detection was carried out for an example beam using the proposed method, and the identified crack locations and sizes agree reasonably well with the exact values.

이종 테이퍼 형식 구조물의 결함추정기법

이종원(Lee, Jong-Won) 대한건축학회 2023 대한건축학회논문집 Vol.39 No.10

In tall buildings, there is a common use of taper-type structures, where structural properties change with height. Cantilever-type structures, which combine different taper types, are also considered. This paper introduces a method for identifying faults in a cantilever beam consisting of two tapered beam sections. To achieve this, a technique was first explored to estimate the modal characteristics of the un-cracked beam by considering boundary and continuity conditions. Then an equivalent bending stiffness was introduced for the cracked beam and an integral characteristic equation was established to estimate its natural frequency. This method was applied, along with neural network techniques, to identify cracks in a sample structure. Through numerical simulations and the generation of neural network training patterns, the sizes and locations of cracks were successfully identified. This suggests that this approach can be valuable for detecting faults in differently tapered cantilever-type structures.

Modal Strain Energy-based Damage Monitoring in Beam Structures using PZT's Direct Piezoelectric Response

호 득 유이,이포영,김정태,Ho, Duc-Duy,Lee, Po-Young,Kim, Jeong-Tae Computational Structural Engineering Institute of 2012 한국전산구조공학회논문집 Vol.25 No.1

본 연구에서는 PZT 소자의 정압전 효과에 의한 동적 응답신호를 이용하는 보 구조물 손상 모니터링 기법을 제안하였다. 특히, 모드 변형에너지기반 보 구조물 손상 모니터링에 PZT 정압전 응답신호를 입력자료로 활용하는 방안에 대한 연구에 주안점이 있다. 먼저, PZT 소자의 정압전 효과 및 동적 변형률 응답의 이론적 배경을 요약하였다. 다음으로, 모드 변형에너지기반 보 구조물 손상위치 모니터링 기법을 제시하였다. 제시된 기법의 적합성을 검증하기 위해, 캔틸레버 보 모형을 대상으로 강제진동 실험을 수행하였으며, 세 종류의 센서(가속도계, PZT 센서, 변형률계)를 통해 동적 응답신호가 계측되었다. 손상 전후에 계측된 이들 진동신호들을 사용하여 모드 변형에너지기반의 손상위치 모니터링이 수행되었다. The main objective of this study is to examine the feasibility of using lead zirconate titanate (PZT)'s direct piezoelectric response as vibrational feature for damage monitoring in beam structures. For the purpose, modal strain energy (MSE)-based damage monitoring in beam structures using dynamic strain response based on the direct piezoelectric effect of PZT sensor is proposed in this paper. The following approaches are used to achieve the objective. First, the theoretical background of PZT's direct piezoelectric effect for dynamic strain response is presented. Next, the damage monitoring method that utilizes the change in MSE to locate of damage in beam structures is outlined. For validation, forced vibration tests are carried out on lab-scale cantilever beam. For several damage scenarios, dynamic responses are measured by three different sensor types (accelerometer, PZT sensor and electrical strain gage) and damage monitoring tasks are performed thereafter. The performance of PZT's direct piezoelectric response for MSE-based damage monitoring is evaluated by comparing the damage localization results from the three sensor types.

말단질량을 갖는 테이퍼 원형강관 캔틸레버 보의 균열탐지기법

이종원(Lee, Jong-Won) 대한건축학회 2016 大韓建築學會論文集 : 構造系 Vol.32 No.4

A crack identification method using the change of natural frequencies for tapered cantilever pipe-type cracked beam is presented. Modal properties of tapered cantilever intact beam with a tip mass are identified by applying the boundary conditions to a general solution. An equivalent bending stiffness for cracked beam based on an energy method is used to identify natural frequencies of tapered cantilever thin-walled pipe with a tip mass, which has a through-the-thickness crack, subjected to bending. The identified natural frequencies of the cracked beam are used in constructing training patterns of neural networks. Then crack location and size are identified using a committee of the neural networks. Crack detection was carried out for an example tapered beam using the proposed method, and the identified crack locations and sizes agree reasonably well with the exact values.

지진 하중 작용시 인공 신경망을 이용한 캔틸레버보의동적 거동 예측에 관한 연구

문현수(Moon, Hyun Su),이정운(Lee, Jeong Un),임윤묵(Lim, Yun Mook) 대한토목학회 2017 대한토목학회 학술대회 Vol.2017 No.10

모터 회전방식 라이다를 활용한 구조물의 동적 거동 추정

이재훈 ( Lee Jaehun ),이제형 ( Lee Jehyung ),송상훈 ( Song Sanghoon ),김은주 ( Kim Robin Eunju ) 한국구조물진단유지관리공학회 2021 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.25 No.1

동적 거동은 구조의 동적 특성을 설명하는 가장 중요한 측정량 중 하나이다. 측정된 거동에서 속도, 가속도 및 편향을 얻을 수 있으며, 구조물의 물리적 매개변수도 추정이 가능하다. 이러한 동적거동 정보의 유용성에도 불구하고 거동을 직접 측정하는 것은 어려운 일이다. 현재 구조물의 동적거동을 측정하기 위한 센서는 크게 접촉식 센서와 비접촉식 센서로 나뉜다. 접촉식 센서의 경우 구조물에 직접 부착되는 센서로서, 구조물과 함께 자연상태에 노출되기 때문에 유지관리가 어렵고 센서의 노후화가 빠르게 진행된다는 단점이 있다. 이러한 문제를 극복하고자 최근 비접촉식 센서 분야가 관심을 받고 있다. 이와 같은 경우 센서와 측정 대상물 사이의 날씨, 온도 등의 환경의 영향을 많이 받는다. 본 연구에서는 최근 자율주행 차량과 함께 각광받고, 기존 센서의 방식에서 나아가 주변 환경의 영향을 적게 받는 라이다 센서를 통한 구조물의 동적거동을 측정한 후 비교분석하였다.