회귀분석법에 의한 복합재료 적층판의 인장 파손특성 분석

이명건(Myoung Keon Lee),오광근(Kwang Keun Oh),김재훈(Jae Hoon Kim) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11

Failure theory that is widely used in composit structure is first ply failure. It regards failure of a ply as laminate failure. This theory predicts correct failure by using strength characteristic of lamina. but, It is leading to conservative results because laminate can endure force when failing a lamina. Recently, advanced airline uses laminate failure theory that estimate strain of composit structure for airplanes. It is important to get value of mechanical fracture characteristic for the entire range of applicable layups (percentage of 0°, +/-45° and 90° plies) before appling laminate failure theory. This paper contains the results of tensile failure characteristics developed by using regression analysis method. The regression analysis is performed with the response variable being the laminate ultimate fracture strength and the regressor variables being two ply orientation(0° and ±45°) variables. Composit material is a 350°F(177°C) cured, carbon fiber reinforced plastic(CFRP) composite material system that incorporates an epoxy resin. The specimens used in this paper is designed with plies oriented only in four standard orientation of 0°, +45°, -45° and 90°. All specimens contain a minimum of 10% plies in each of the 0°, +45°, -45° and 90° orientations, thus ensuring that all test experienced a fiber failure mode without significant non-linearities in the load-strain response. A total of 149 tension tests were conducted on specimens from 14 distinct laminates and 3 material batches. ASTM-D-3039 was used for test method

첨단복합재료 적층판의 볼트 단일접합 강도 시험적 평가

이명건(Myoung Keon Lee),이정원(Jeong Won Lee),윤동현(Dong Hyun Yoon),김재훈(Jae Hoon Kim) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12

Advanced composite material consists of fibers of high specific strength and stiffness embedded in a stabilizing resin matrix of lower stiffness and strength. For composite structure, the longitudinal tension and compression are carried by the fibers. The matrix distributes the load between the fibers for the tension case and it stabilizes and prevents the fibers from buckling for the compression case. The fiber dominates the tensile properties and the matrix dominates the compression and in-plane shear. The lap shear joint where all of the load in the structural members is transferred through the joining fasteners. This paper presents joint strength for laminate of advanced composite material in the bolted joints. The single lap joints were investigated experimentally with respect to stabilized and unstabilized lap joints. The stabilized single lap joint means joints with out-of-plane rotational constraints. The unstabilized single lap joint is joint without out-of-plane deflection constraints. The standard angles 0 degree, +45 degree, -45 degree and 90 degree, in the laminate reference system, were used for ply orientation within a laminate. The composite material used in this paper is a carbon/epoxy unidirectional(UD) tape prepreg cured at 350F. A total of 112 single lap joint tests were conducted on specimens from 8 distinct laminates. The ASTM-D-5961M standard was used for stabilized and unstabilized single lap shear joints.

첨단복합재료 적층판의 인장 파손특성 시험적 평가

이명건(Myoung Keon Lee),이정원(Jeong Won Lee),윤동현(Dong Hyun Yoon),김재훈(Jae Hoon Kim) 대한기계학회 2017 大韓機械學會論文集A Vol.41 No.10

최근 선진항공사에서는 항공기 복합재 구조의 변형률을 평가할 때 적층판 파손이론을 사용한다. 적층판 파손이론은 복합재 구조평가에 적층판의 파손변형률을 사용한다. 본 논문은 적층판 인장파손특성의 시험적 평가 절차를 보여준다. 시험적 평가는 회귀분석법(regression analysis method)을 사용하였다. 회귀분석은 적층판의 파손변형률을 응답변수로 하고 적층판 내 0°, ±45°층의 비율을 회귀변수로 하는 방법이다. 본 논문에 사용된 복합재료는 177°C(350°F)에서 경화되는 Carbon/Epoxy UD Tape 프리프레그이다. 시편은 0°, +45°, -45° 및 90°층으로 적층된 14 종류의 노치없는 적층판으로 총149개 시편으로 구성하였다. 시험방법은 ASTM-D-3039 규정을 사용하였다. In recent years, major airplane manufacturers have been using the laminate failure theory to estimate the strain of composite structures for airplanes. The laminate failure theory uses the failure strain of the laminate to analyze composite structures. This paper describes a procedure for the experimental assessment of laminate tensile failure characteristics. Regression analysis was used as the experimental assessment method. The regression analysis was performed with the response variable being the laminate failure strain and with the regressor variables being two-ply orientation (0° and ±45°) variables. The composite material in this study is a carbon/epoxy unidirectional (UD) tape that was cured as a pre-preg at 177°C(350°F). A total of 149 tension tests were conducted on specimens from 14 distinct laminates that were laid up at standard angle layers (0°, 45°, -45°, and 90°). The ASTM-D-3039 standard was used as the test method.

회귀분석법에 의한 복합재료 적층판의 압축파손강도 개발

이명건(Myoung Keon Lee),이정원(Jeong Won Lee),윤동현(Dong Hyun Yoon),김재훈(Jae Hoon Kim) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.4

회귀분석법에 의한 복합재료 적층판의 압축파손강도 개발

이명건(Myoung Keon Lee),이정원(Jeong Won Lee),윤동현(Dong Hyun Yoon),김재훈(Jae Hoon Kim) 대한기계학회 2016 大韓機械學會論文集A Vol.40 No.10

본 논문에서는 회귀분석법(regression analysis method)을 사용하여 개발된 복합재 적층판의 압축 파손강도값을 수록하였다. 본 논문에 사용된 복합재료는 350°F(177℃)에서 경화되는 Carbon/Epoxy UD Tape 프리프레그(Cycom G40-800/5276-1)이며 운용온도 범위는 -60°F~+200°F(-55℃~+95℃)이다. 시편은 0°, +45°, -45° 및 90°층으로 적층된 8종류의 노치없는 적층판으로 총 56개 시편으로 구성하였다. 시험방법은 ASTM-D-6484 규정을 사용하였다. 적층판의 압축 파손강도값은 적층판 내 0°와 ±45°층의 적층비율을 변수로 하는 회귀 분석법(regression analysis method)을 사용하여 획득하였다. This paper provides the compressive failure strength value of composite laminate developed by using regression analysis method. Composite material in this document is a Carbon/Epoxy unidirection(UD) tape prepreg(Cycom G40-800/5276-1) cured at 350°F(177℃). The operating temperature is –60°F~+200°F(-55℃~+95℃). A total of 56 compression tests were conducted on specimens from eight (8) distinct laminates that were laid up by standard angle layers (0°, +45°, –45° and 90°). The ASTM-D-6484 standard was used for test method. The regression analysis was performed with the response variable being the laminate ultimate fracture strength and the regressor variables being two ply orientations (0° and ±45°).

첨단복합재료 적층판의 볼트단일접합 강도 시험적 평가

이명건(Myoung Keon Lee),이정원(Jeong Won Lee),윤동현(Dong Hyun Yoon),김재훈(Jae Hoon Kim) 대한기계학회 2017 大韓機械學會論文集A Vol.41 No.10

본 논문에서는 첨단복합재의 볼트단일접합 베어링강도에 대한 시험적 평가 결과를 수록하였다. 볼트단일접합 시험은 stabilized 접합과 unstabilized 접합에 대하여 수행하였다. Stabilized 접합은 접합부 면외회전을 제한하는 접합이다. Unstabilized 접합은 면외변위를 제한하지 않는 접합이다. 볼트 단일접합에서 적층판의 베어링강도 값은 적층판 내 적층각 0°, +45°, -45° 및 90° 비율에 영향이 없음을 보여준다. 볼트접합부 면외거동의 영향으로 unstabilized 볼트 단일접합 베어링 강도값이 stabilized 볼트 단일접합 베어링 강도값 보다 작음을 보여주고 있다. 본 논문에 사용된 복합재료는 177°C(350°F)에서 경화되는 Carbon/Epoxy UD Tape 프리프레그이다. 표준각 0°, +45°, -45° 및 90° 층으로 적층된 8종류의 적층판에서 총 112개 볼트단일접합 시험시편을 구성하였다. Stabilized 접합과 unstabilized 접합의 시험방법은 ASTM-D-5961M 규정을 사용하였다. This paper presents the bearing strength for laminates in advanced composite materials in bolted joints. Bolted single lap joint tests were experimentally investigated with respect to stabilized and unstabilized lap joints. Stabilized bolted single lap joints refer to joints with out-of-plane rotational constraints. Unstabilized bolted single lap joints refer to joints with absence of out-of-plane deflection constraints. The bearing strength values of laminates in the bolted joint showed that the percentages of ply angle for 0, 45, -45, and 90 degrees were not affected. The bearing strength value in the unstabilized bolted joint was smaller than the bearing strength value in the stabilized bolted joint because of the influence of the out-of-plane behavior. The composite material studied in this paper is a carbon/epoxy unidirectional (UD) tape prepreg cured at 177°C (350°F). In the laminate reference system, the standard angles of 0, 45, -45, and 90 degrees were used for ply orientation within the laminate. A total of 112 bolted single lap joint tests were conducted on specimens from eight distinct laminates. The ASTM-D-5961M standards were adhered to for the stabilized and unstabilized bolted single lap joint tests.

날개끝 스토어 형상 항공기 복합재 날개 구조의 MDO 연구

전승문(Seung-Moon Jun),이명건(Myoung-Keon Lee),이재화(Jae-Hwa Lee) 한국항공우주학회 2004 韓國航空宇宙學會誌 Vol.32 No.2

본 논문에서는 날개끝 스토어가 장착된 항공기 복합재 날개구조에 대한 다분야 통합 최적화 설계를 수행하였다. 스토어 위치, 중량 및 공력효과 등을 고려하여 복합재 날개구조 설계 과정에서 중요한 고려인자가 무엇인지 파악하고자 하였다. 정적강도, 제작한계 및 플러터 속도를 구속조건으로 하여 ICW 날개 모델을 최적화 하였다. 각 요소의 두께와 단면적을 설계 변수로 사용하였다. 최적화 설계 도구로서 MSC/NASTRAN을 사용하였다. 실용적인 설계 관점에서 복합재 적층 파손식 적용을 검토 하였다. 날개끝 스토어의 공기력 효과가 ICW 날개 모델의 공탄성 불안정 특성에 큰 영향을 주었다. 최적화된 구조의 공탄성 불안정성이 날개끝 스토어가 날개 시위방향으로 움직임에 따라 아주 민감하게 변화하였다. 이러한 결과로 볼 때 날개끝 스토어 모델의 정밀도가 설계 과정에서 아주 중요한 인자임을 알 수 있었다. This paper presents MDO(Multidisciplinary Design Optimization) study results for aircraft composite wing structure with tip store. The objective is to identify key design parameters in the composite wing structure design process. The store location and the effect of the store aerodynamics and mass are the variables included. The ICW(Intermediate Complexity Wing) wing box model is optimized with constraints on the static strength, manufacturing limit and flutter speed. The thicknesses and the cross-sectional areas of the structural elements are the design variables in the optimization. The MSC/NASTRAN is the primary tool used in this study. Failure criteria of composite laminate are examined regarding the practical design. The aerodynamics of the tip store significantly affects the aeroelastic instability of ICW model. The aeroelastic instability of the optimized structure is very sensitive to the tip store movement along the tip chord. The present results indicate that the selection of tip store model fidelity is very important during the design process.

주파수 선택적 투과막이 결합된 복합재료의 잔류응력평가 및 선택적 투과막 설계

김가연 ( Ka Yeon Kim ),전흥재 ( Heoung Jae Chun ),강경탁 ( Kyung Tak Kang ),이경원 ( Kyung Won Lee ),홍익표 ( Ic Pyo Hong ),이명건 ( Myoung Keon Lee ) 한국복합재료학회 2011 Composites research Vol.24 No.1

본 연구에서는 최적화 알고리즘 중 하나인 PSO기법을 이용하여 주파수 선택적 표면을 설계하였으며, 설계된 주파수 선택구조를 적용한 하이브리드 레이돔의 잔류응력을 예측하였다. 주파수 선택 구조로서 Square Loop의 등가회로모델에 PSO를 적용하여, K-band(23GHz)에서 차단특성을 갖는 최적의 설계값을 구하였다. 또한 FSS와 복합재료의 하이브리드 레이돔을 제작할 때 발생하는 잔류응력의 효과가 클 경우 구조적 안정성이 떨어질 뿐만 아니라 층간분리가 발생하여 FSS의 전파투과특성에 영향을 미칠 수 있으므로, 하이브리드 레이돔의 제작 시에 동시경화 후 상온으로 냉각되는 과정에서 발생하는 잔류 열응력에 대하여 예측하였으며, FSS패턴과 복합재료의 적층각 변화에 따른 영향을 비교하였다. In this paper, Particle Swarm Optimization(PSO) is applied to the design of the Frequency Selective Surface(FSS) and residual stresses of hybrid radome is predicted. An equivalent circuit model with Square Loops arrays was derived and then PSO was applied for acquiring the optimized geometrical parameters with proper resonant frequency. Residual stresses occur in the FSS embedded composite structures after cocuring and have a great influence on the strength of the FSS embedded composite structures. They also effect transmission quality because of delamination. Therefore, the thermal residual stresses of FSS embedded composite structures were analyzed using finite element analysis with considering the effects of FSS pattern, and composite stacking sequence.