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최순권,박세만,박명균 明知大學校 産業技術硏究所 2002 産業技術硏究所論文集 Vol.21 No.-
Structral composite materials have progressed to become light- weighted and their applications have been on the rise for automobiles, aircrafts, ships and other structrues that require high strength. This have inevitably produced an trend fur research activities to be focused on the structural composite materials. In this study where composite laminated plates are subject to impacts, static indentation law - modified tertian contact law - is evoked to investigate the dynamic behavior of the composite plates. Briefly speaking, there are spring-mass model, energy balance model, assumed force method and modified Hertzian contact law that are available for evaluations of dynamic impact behaviors of composite laminated plates. These methods generally make certain assumptions to idealize problems encountered in reality . The hgiher order shear deformation theory as well as its refined theory, both of which are basically 2D plate theories, are considered to compute in-plane stresses and transverse shear stresses. The both types of stresses are essential to predict internal damages under low velocity impacts. Time integrations are conducted with the Newmark method and current results from this work are compared with those available in the literature.
두 가지 동적 진동실험을 이용한 Carbon-Epoxy와 Graphite-Epoxy복합재료의 동적 탄성계수 측정
박세만,박명균,최순권 명지대학교 산업기술연구소 2001 産業技術硏究所論文集 Vol.20 No.-
As requirements for the weight reduction and the higher strength of structures in use have become strict composite materials have been frequently utilized in many industrial products. Accordingly, it becomes essential that designs of safe structures are ensured and furthermore their proper inspections should be in order subsequently at any cost. In light of this, accurate measurements of elastic constants, which is one of major mechanical properties, warrant careful considerations. In this research the two dynamic vibratory techniques, acoustic resonance method and impulse method, are employed in parallel to directly compare the two techniques and to evaluate the elastic constants more accurately.