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장인준(Injoon Jang),이우식(Usik Lee) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
As the blood flow characteristics are closely related to various cardiovascular diseases, it is very important to predict them accurate enough in an efficient way. Thus, this paper proposes a one-dimensional spectral element model for human blood vessels. The spectral element model is formulated by using the variational approach of finite element formulation. The wave solutions analytically solved in the frequency-domain to satisfy governing equations are used to determine the frequency-dependent interpolation functions.
Spectral element modeling for the dynamic analysis of axial-bending-shear coupled composite beam
Injoon Jang(장인준),Usik Lee(이우식) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
It has been well-recognized that fiber reinforced composite materials have many advantages over the isotropic materials due to their high strength-to-density ratios. Thus they have been widely used in many industrial applications. Typical examples of industrial applications are the composite aircraft wing, helicopter blade, propeller blade, turbine blade, axles of vehicle and so on. Of particular interest especially for the high aspect ratio composite laminated structures (beams) are the coupling among the extensional (axial), bending and torsional modes of deformation. As fibrous composite materials have usually very low shear modulus, the shear deformation should be also included in the analysis and design of such composite laminated beams. Thus, this paper covers the dynamics of the axial-bending-shear coupled beam, all based on the first-order shear deformation theory (FSDT) which is the equivalent to the Timoshenko beam theory for composite laminated beams.
축 방향 하중을 받는 인장-굽힘-전단이 연성된 복합재 적층보의 파동특성
장인준(Injoon Jang),이우식(Usik Lee) 한국철도학회 2011 한국철도학회 학술발표대회논문집 Vol.2011 No.10
The fiber reinforced composite materials have many advantages due to their high strength-to-density ratios. Thus they have been widely used in many industrial applications. As the wave propagation are closely related to dynamic analysis of structures it is very important to predict them. This paper presents a wave propagation in the axially loaded axial-bending-shear coupled composite laminated beams which are represented by the Timoshenko beam models based on the first-order shear deformation theory.
장인준(Injoon Jang),이우식(Usik Lee) 한국철도학회 2012 한국철도학회 학술발표대회논문집 Vol.2012 No.10
항공기 날개 등의 구조물 손상은 패치를 이용한 수리가 경제성 등 여러 면에서 유리하다. 패치의 재료 중 복합재료는 우수한 비강도로 널리 사용되고 있다. 따라서 본 연구에서는 복합재 패치가 부착된 등방성 보에 대하여 1차 전단변형 이론을 적용한 Timoshenko beam 이론과 Mindlin-Herrmann rod 이론을 적용하여 축 방향 변형, 굽힘 변형, 전단 변형 및 수축 변형이 서로 연성된 동력학 모델을 유도하고 여기에 variation method를 적용하여 스펙트럴요소 모델을 유도하였다. 본 연구에서 유도한 스펙트럴요소 모델은 별도로 유도한 유한요소모델과의 비교를 통하여 그 정확성을 검증하였다. Damaged structures should be replaced or repaired. However, in many cases, the replacement of structure is impossible or need to cost a lot. The fiber reinforced composite materials have many advantages due to their high strength-to-density ratios. Thus they have been widely used in many industrial applications. The composite patched beams are represented by the Timoshenko beam model based on the first-order shear deformation theory and Mindlin-Herrmann rod theory. The high accuracy of the spectral element model is then numerically verified by comparing with solutions obtained by finite element method.