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탄소섬유 복합재의 Bi-modulus 특성을 반영한 풍력 터빈 블레이드 구조해석
주근수,문진범,김시현,강민규,김지훈 한국풍력에너지학회 2022 풍력에너지저널 Vol.13 No.3
This paper deals with the structural analysis of wind turbine blades considering the bi-modulus property of CFRP, known as a more economic and efficient material for very large blades. The bi-modulus property is an unique characteristic of CFRP that shows higher tensile modulus than compressive modulus. Due to this characteristic, it is needed to apply the bi-modulus property to the computational analysis of CFRP blades to achieve more accurate results. In this paper, a novel method is proposed to apply the bi-modulus property of CFRP in a numerical simulation. To demonstrate the bi-modulus effect in FE analysis, the actual bi-modulus of CFRP was measured and applied to the structural analysis of a wind turbine blade. Moreover, the effects of the proposed method were evaluated by comparing the analysis results with actual full-scale blade static test results. As a result, it was verified that the proposed method could appropriately simulate the bi-modulus during FE analysis. Moreover, the accuracy of blade structural analysis was improved in accordance with the application of the bi-modulus property.
주근수,김진봉,정문규,김영철,Böhm Holger,Richter Jonas 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.5
This paper is concerned with numerical simulation utilizing LS-DYNA MAT54 for axial crush of glass-fiber mat/PA6 composite tubes. The crush simulation aims at reproducing the crush energy absorption capability measured from dynamic drop tests. The adopted MAT54 has a merit as a widely commercialized model of composite materials to simulate a progressive failure mode. Parameters of MAT54 are calibrated to reduce difference of the crush energy absorption capability between experiment and simulation on the basis of parametric studies. The calibration is performed for major parameters considering effect of energy absorption and stability of crush simulation first, and other parameters are determined by a trial and error method. In order to evaluate the calibrated parameters of MAT54, results are compared for specific energy absorption and crush depths measured from simulation and experiment. Consequently, the presented simulation shows good agreements with experiments, and its applicability is verified under various impact speed and impactor mass conditions.
중 변형률속도 영역에서 차체 강판의 인장/압축 경화 거동에 관한 연구
주근수(Guensu Joo),최민국(Min Kuk Choi),허훈(Hoon Huh) 한국자동차공학회 2014 한국자동차공학회 부문종합 학술대회 Vol.2014 No.5
The tension/compression hardening behavior is important in sheet metal forming processes because of complicated loading paths. Experimental methods to measure the tension/ compression behavior have not considered the effect of the strain rate although the strain rate is related to the hardening behavior of sheet metal. The tension/compression tests need to be conducted considering the strain rate to acquire accurate hardening behavior. This paper deals with an experimental technique to measure the tension/compression behavior of sheet metal at strain rates from 0.001 s<SUP>-1</SUP> to 50 s<SUP>-1</SUP> for real sheet metal forming. A new clamping device was developed to prevent a sheet specimen from buckling under compression loading condition. Jig systems to impose pre-strain and reverse loading were also developed for high speed material testing machine. Tension/compression tests have been conducted at various strain rates for SPCC and DP590 with pre-strain of 10%. Hardening behavior under the tension or compression loading condition was compared to each other at severe strain rates.
주근수(Geunsu Joo),허훈(Hoon Huh),정영혁(Yeong Hyuk Jung),김주영(Ju Yeong Kim),서송원(Songwon Seo) 대한기계학회 2017 大韓機械學會論文集A Vol.41 No.9
본 논문에서는 포신의 강선을 고려한 포 발사 해석기법을 다룬다. 포 발사 환경에서 탄두는 고충격 및 고회전의 동적 거동이 발생한다. 이러한 동적 거동에서 탄두 및 탄두 내 전자 장비가 손상되는 사례가 발생하고 있다. 따라서 포 발사 환경에서 탄두의 동적 거동 분석 및 생존성 평가를 위한 포 발사 해석기법의 개발이 필요한 실정이다. 본 논문에서는 앞서 선행연구자들의 단순화된 포 발사 해석기법을 개선하여, 포신의 강선과 탄대의 접촉에 따른 탄두의 회전을 구현할 수 있는 포 발사 해석기법을 개발하였다. 개발된 포 발사 해석기법은 실험결과와 비교를 통하여 검증하였으며, 제안된 해석기법을 이용하여 포 발사 시 탄두의 동적 거동 및 생존성을 평가하였다. This paper is concerned with numerical simulation of a gun-launched projectile considering a rifled gun-tube. Gun-launched conditions induce dynamic behaviors, such as high pressure and high speed rotation. A projectile and its internal electronic components may be damaged in such harsh environments. Hence, it is necessary to perform numerical simulation of a gun-launched projectile to predict its dynamic behaviors and stability. In this work, preceding research studies on gun-launched projectiles are investigated, and the simulation method is developed to rotate the projectile through between its rotating band and a rifled-gun tube. The proposed method is verified by comparison with experimental results, and the dynamic behaviors and stability of the projectile are evaluated under gun-launched conditions.
유리섬유 부직포가 삽입된 풍력 블레이드 인발 성형 스파캡 소재의 파괴인성 특성 평가
김영철,주근수,박지상,이우경,강민규,김지훈 한국풍력에너지학회 2023 풍력에너지저널 Vol.14 No.3
The purpose of this study is to evaluate the inter-laminar fracture toughness characteristics of CFRP pultrusion spar cap materials reinforced with non-woven glass fabric. Test specimens were fabricated by the infusion technique. A non-woven glass fabric and artificial defects were embedded on the middle surface between two pultruded CFRP panels. Double cantilever beam (DCB) and End Notched Flexure (ENF) tests were performed according to ASTM standards. Fracture toughness and crack propagation characteristics were evaluated with load-displacement curves and delamination resistance curves (R-Curve). The fracture toughness results were calculated by compliance calibration (CC) method. The initiation and propagation values of Mode-I critical strain energy release rate value were 1.357 kJ/m2 and 1.397 kJ/m2 , respectively, and Mode-II critical strain energy release rate values were 4.053 kJ/m2 for non-precracked test and 4.547 kJ/m2 for precracked test. It was found that the fracture toughness properties of the CFRP pultrusion spar-cap are influenced by the interface between the layers of CFRP and glass fiber non-woven.
유한요소해석을 이용한 압축 하중을 받는 오픈 홀 복합재 시편의 점진적 손상 및 파손 분석
김영철,주근수,장홍규,김진봉,강민규,이우경,김지훈,Young Cheol Kim,Geunsu Joo,Hong-Kyu Jang,Jinbong Kim,Min-Gyu Kang,Woo-Kyoung Lee,Ji Hoon Kim 한국복합재료학회 2023 Composites research Vol.36 No.5
In this paper, a Progressive Damage and Failure Analysis (PDFA) modeling method was developed using ABAQUS/EXPLICIT to predict in-plane damage and delamination for Open-Hole Compression (OHC) testing. The proposed PDFA model was constructed based on Hashin criteria and cohesive behavior. The strength and stiffness of OHC specimens with three types of stacking sequences [(45/-45/0<sub>2</sub>)<sub>3</sub>]<sub>s</sub> , [(45/0/-45/90)<sub>3</sub>]<sub>s</sub> and [45/-45/0/45/-45/90/(45/-45)<sub>2</sub>]<sub>s</sub> were compared to comprehensively evaluate the validity of the Finite Element(FE) model of PDFA. The strength and stiffness of the OHC specimens were predicted relatively well, with less than a percentage error 10.0 %. For the numerical simulation case for each layup, the damage initiation/evolution of OHC specimens were evaluated for delamination and tension/compression matrix damage before and after failure.