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티모센코 보방정식에 의한 카본-에폭시 복합재료의 탄성계수 변화에 관한 연구
김형삼,이재혁,이동식,박세만 명지대학교 대학원 1999 대학원논문집 Vol.3 No.-
Usages of composite materials have been steadily on the rise in the industries of automobiles, air crafts, shipbuilding and other structures for transportations. Commonly required in those industries are light weight and high strength of the structures. Consequently, serious efforts in research have been focused on searching for light materials and on developments and characterization of advanced substitutes including various kinds of composite materials. In this investigation, transversely isotropic composite materials are chosen and formed into two kinds of beams: Euler-Bernoulli beam(thin beam) and Timoshenko beam(thick beam) for determinations of elastic constants. As an experimental technique Acoustic Resonance Method is utilized to measure resonance frequencies of the beams of the composite materials in vibration tests. Elastic constants are evaluated from measured resonance frequencies for the two types of beams to observe and establish possible existence of effects of rotary inertia and shear deformations.
Impulse Excitation Method에 의한 복합재료의 공진 주파수와 탄성계수 관계에 대한 실험적 고찰
김형삼,이재혁,이동식,박세만,Kim, Hyeong-Sam,Lee, Jae-Hyeok,Lee, Dong-Sik,Park, Se-Man 한국재료학회 1998 한국재료학회지 Vol.8 No.9
결량화 되고 고강도의재료를 요하는 자동차, 항공기, 선박, 각종 구조물 등 여러 분야에서 복합재료의 사용은 증가되어 왔고, 그에 따라 연구가 활발히 진행되고 있다. 본 연구에서는 Impulse Excitation Method을 통해 Transversely Isotropic한 재료의 공진 주파수를 측정함으로써 복합재료의 탄성계수를 구하였다. Timoshenko Beam Equation식에 나타나는 회전관성효과와 전단변형을 고려하였을 때와 고려하지 않았을 때 재료의 탄성계수에 변화가 어떻게 나타나는 가를 관찰하였다. The Usages of composite materials have been steadily on the rise in the industries of automobiles, air crafts, shipbuilding and other structures for transportations. Commonly required in those industries are light weight and high strength of the structures. Consequently, serious efforts in research have been focused on searching for light materials and on developments and characterizations of advanced substitutes including various kinds of composite materials. In this investigation, transversely isotropic composite materials are chosen and formed into two kinds of beams; Euler-Bernoulli beam(thin team) and Timoshenko beam(thick beam) for determinations of elastic constants. As an experimental technique Impulse Excitation Method is utilized to measure resonance frequencies of the beams of the composite materials in vibration tests. Elastic constants are evaluated from measured resonance frequencies for the two types of beams to observe and establish possible existence of effects of rotary inertia and shear deformations.
공진주파수 측정을 통한 복합재료의 탄성계수 측정과 이론식과의 비교 평가
김형삼(H.S.Kim),박세만(S.M.Bahk),박명균(M.K.Park),이재혁(C.H.Yi),최흥섭(H.S.Choi) 한국자동차공학회 1997 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1997 No.11_2
The need to develop and use light-weight structural components in the design of aircraft and automotive vehicles has brought increasing applications of composite materials. To evaluate elastic constants which are one of important mechanical properties of composite materials a method of experimentation is conceived and an experimental set-up is constructed to evaluate elastic constants of composites. The experimental method utilizes resonance phenomenon which occurs when natural frequencies of materials match externally applied frequencies. Flexural resonance frequencies are determined to evaluate Young's moduli E} and E2 which torsional resonance frequencies are measured to evaluate shear moduli G_13 and G_23. The experimentally determined values of elastic constants are compared with those values computed from theoretical considerations utilizing the rule of mixtures to establish the extent of agreement between the experimental and theoretical methods.