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광 적외선열화상을 이용한 풍력 블레이드의 결함 크기 정량화 연구
권구안,최만용,박희상,박정학,허용학,최원재,Kwon, Koo-Ahn,Choi, Man-Yong,Park, Hee-Sang,Park, Jeong-Hak,Huh, Yong-Hak,Choi, Won Jae 한국비파괴검사학회 2015 한국비파괴검사학회지 Vol.15 No.1
풍력발전기의 핵심 부품인 풍력 블레이드는 예상치 못한 풍 하중과 공력 특성으로 인해 불안전한 상태에 놓여 있다. 그에 따라 필연적으로 발생하는 내부 결함을 검출하기 위해 초음파탐상을 이용한 비파괴검사가 주로 진행되어 왔다. 하지만 블레이드의 소재 특성으로 인해 음향 신호 분석에 따른 문제점이 발생한다. 따라서 본 연구에서는 풍력 블레이드 인공결함시험편을 제작후, 능동적 광 적외선열화상 비파괴검사 방법을 이용하여 결함의 크기를 정량화하기 위한 실험을 진행하였다. 100 kW 급 블레이드 내부의 결함 크기 정량화를 위해 알루미늄 켈리브레이션 테이프를 사용하였으며, 게재물(inclusion), 디본딩(debonding), 주름(wrinkle) 결함을 삽입하였다. 실험 결과 모두에서 뚜렷한 결함 검출이 가능하였으며, 결함 크기 정량화 결과 debonding 인공 결함 (${\phi}50.0mm$)에서 최대 98.0%의 정확성을 보였다. A wind turbine blade is an important component in wind-power generation, and is generally exposed to harsh environmental conditions. Ultrasonic inspection is mainly used to inspect such blades, but it has been difficult to quantify defect sizes in complicated composite structures. Recently, active infrared thermography has been widely studied for inspecting composite structures, in which thermal energy is applied to an object, and an infrared camera detects the energy emitted from it. In this paper, a calibration method for active optical lock-in thermography is proposed to quantify the size. Inclusion, debonding and wrinkle defects, created in a wind blade for 100 kW wind power generation, were all successfully detected using this method. In particular, a ${\phi}50.0mm$ debonding defect was sized with 98.0% accuracy.
Study on the Defects Detection in Composites by Using Optical Position and Infrared Thermography
권구안,박희상,박정학,최원재 한국비파괴검사학회 2016 한국비파괴검사학회지 Vol.36 No.2
Non-destructive testing methods for composite materials (e.g., carbon fiber-reinforced and glass fiber- reinforced plastic) have been widely used to detect damage in the overall industry. This study detects defects using optical infrared thermography. The transient heat transport in a solid body is characterized by two dynamic quantities, namely, thermal diffusivity and thermal effusivity. The first quantity describes the speed with thermal energy diffuses through a material, whereas the second one represents a type of thermal inertia. The defect detection rate is increased by utilizing a lock-in method and performing a comparison of the defect detection rates. The comparison is conducted by dividing the irradiation method into reflection and transmission methods and the irradiation time into 50mHz and 100mHz. The experimental results show that detecting defects at 50mHz is easy using the transmission method. This result implies that low-frequency thermal waves penetrate a material deeper than the high-frequency waves.
권구안,박희상,최만용,박정학,최원재 한국비파괴검사학회 2017 한국비파괴검사학회지 Vol.37 No.2
Many composite materials are used in the aerospace industry because of their excellent mechanical properties. However, the nature of aviation exposes these materials to high temperature and high moisture conditions depending on climate, location, and altitude. Therefore, the molecular arrangement chemical properties, and mechanical properties of composite materials can be changed under these conditions. As a result, surface disruptions and cracks can be created. Consequently, moisture-impregnating defects can be induced due to the crack and delamination of composite materials as they are repeatedly exposed to moisture absorption moisture release, fatigue environment, temperature changes, and fluid pressure changes. This study evaluates the possibility of detecting the moisture-impregnating defects of CFRP and GFRP honeycomb structure sandwich composite materials, which are the composite materials in the aircraft structure, by using an active infrared thermography technology among non-destructive testing methods. In all experiments, it was possible to distinguish the area and a number of CFRP composite materials more clearly than those of GFRP composite material. The highest detection rate was observed in the heating duration of 50 mHz and the low detection rate was at the heating duration of over 500 mHz. The reflection method showed a higher detection rate than the transmission method.
광 적외선열화상을 이용한 풍력 블레이드의 결함 크기 정량화 연구
권구안(Koo-Ahn Kwon),최만용(Man-Yong Choi),박희상(Hee-Sang Park),박정학(Jeong-Hak Park),허용학(Yong-Hak Huh),최원재(Won Jae Choi) 한국비파괴검사학회 2015 한국비파괴검사학회지 Vol.35 No.1
풍력발전기의 핵심 부품인 풍력 블레이드는 예상치 못한 풍 하중과 공력 특성으로 인해 불안전한 상태에 놓여 있다. 그에 따라 필연적으로 발생하는 내부 결함을 검출하기 위해 초음파탐상을 이용한 비파괴 검사가 주로 진행되어 왔다. 하지만 블레이드의 소재 특성으로 인해 음향 신호 분석에 따른 문제점이 발생한다. 따라서 본 연구에서는 풍력 블레이드 인공결함시험편을 제작후, 능동적 광 적외선열화상 비파괴검사 방법을 이용하여 결함의 크기를 정량화하기 위한 실험을 진행하였다. 100 kW 급 블레이드 내부의 결함 크기 정량화를 위해 알루미늄 켈리브레이션 테이프를 사용하였으며, 게재물(inclusion), 디본딩(debonding), 주름(wrinkle) 결함을 삽입하였다. 실험 결과 모두에서 뚜렷한 결함 검출이 가능하였으며, 결함 크기 정량화 결과 debonding 인공 결함 (φ50.0 mm)에서 최대 98.0%의 정확성을 보였다. A wind turbine blade is an important component in wind-power generation, and is generally exposed to harsh environmental conditions. Ultrasonic inspection is mainly used to inspect such blades, but it has been difficult to quantify defect sizes in complicated composite structures. Recently, active infrared thermography has been widely studied for inspecting composite structures, in which thermal energy is applied to an object, and an infrared camera detects the energy emitted from it. In this paper, a calibration method for active optical lock-in thermography is proposed to quantify the size. Inclusion, debonding and wrinkle defects, created in a wind blade for 100 kW wind power generation, were all successfully detected using this method. In particular, a φ 50.0 mm debonding defect was sized with 98.0% accuracy.
신성우,권구안,이종원,Shin, Sung-Woo,Kwon, Koo-Ahn,Lee, Jong-Won 대한건축학회 2011 대한건축학회논문집 Vol.27 No.7
The regions with newly organized meteorological observatory do not have sufficient amount of wind speed data for the extremal analysis, so it is difficult to estimate the Basic Wind Speed using the extremal analysis. Therefore, it is necessary to find a way how to estimate the Basic Wind Speed using the extremal analysis with a few amount of data. This study focuses on the estimation of the Bagic Wind Speed using the daily maximum wind speed data by utilizing the Davenport distribution based Bi-Weibull distribution.
박희상,최만용,권구안,박정학,최원재,정현철 한국비파괴검사학회 2017 한국비파괴검사학회지 Vol.37 No.2
Recently, composite materials have been mainly used in the main wings, ailerons, and fuselages of aircraft and rotor blades of helicopters. Composite materials used in rapid moving structures are subject to impact by hail, lightning, and bird strike. Such an impact can destroy fiber tissues in the composite materials as well as deform the composite materials, resulting in various problems such as weakened rigidity of the composite structure and penetration of water into tiny cracks. In this study, experiments were conducted using a 2 kW halogen lamp which is most frequently used as a light source, a 2 kW near-infrared lamp, which is used for heating to a high temperature, and a 6 kW xenon flash lamp which emits a large amount of energy for a moment. CFRP composite sandwich panels using Nomex honeycomb core were used as the specimens. Experiments were carried out under impact damages of 1, 4 and 8 J. It was found that the detection of defects was fast when the xenon flash lamp was used. The detection of damaged regions was excellent when the halogen lamp was used. Furthermore, the near-infrared lamp is an effective technology for showing the surface of a test object.
신성우(Shin Sung-Woo),권구안(Kwon Koo-Ahn),이종원(Lee Jong-Won) 대한건축학회 2011 大韓建築學會論文集 : 構造系 Vol.27 No.7
The regions with newly organized meteorological observatory do not have sufficient amount of wind speed data for the extremal analysis, so it is difficult to estimate the Basic Wind Speed using the extremal analysis. Therefore, it is necessary to find a way how to estimate the Basic Wind Speed using the extremal analysis with a few amount of data. This study focuses on the estimation of the Bagic Wind Speed using the daily maximum wind speed data by utilizing the Davenport distribution based Bi-Weibull distribution.