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WL - RDCB 시편의 동적 균열전파속도와 동적 응력확대계수
한민구,정석주 한국산업안전학회 1996 한국안전학회지 Vol.11 No.3
Dynamic fracture characteristics of Polycarbonate WL-RDCB specimen were investigated. The dynamic crack propagation velocities in these specimens were measured by using both high speed camera system and silver paint grid method developed and justified in the INHA Fracture Mechanics Laboratory. The measured crack propagation velocities were fed into the INSAMCR code(a dynamic finite element code which has been developed in the INHA Fracture Mechanics Laboratory) to extract the dynamic stress intensity factors. It has been confirmed that both dynamic crack arrest toughness and the static. crack arrest toughness depend on both the geometry and the dynamic crack propagation velocity of specimens. The maximum dynamic crack propagation velocity of Polycarbonate WL-RDCB specimen was found to be dependent on the material property, geometry and the type of loading. The dynamic cracks in these Polycarbonate WL-RDCB specimens seemed to propagate in a successive manner, involving distinguished 'propagation-arrest-propagation-arrest' steps on the microsecond time scale. It was also found that the relat-ionship between dynamic stress intensity factor and dynamic crack propagation velocities might be represented by the typical 'Γ' shape.
한민구 거제전문대학 1997 論文集 Vol.5 No.-
In general, the experimental data of fatigue crack growth rates scatter very much even under same experimental conditions with constant amplitude loading condition. It is, thus, essential to take into account the data scatter of crack growth rates by using statistical approach for a reliable fatigue crack propagation analysis. In this study, fatigue crack propagation tests were conducted on a very thin 2024-T3 Al alloy under constant amplitude loading. The distribution of the fatigue crack propagation lives for airplane thin structure were estimated.
정석주,한민구 서울産業大學校 1992 논문집 Vol.36 No.1
The influence of the elasticity constants, which have been usually neglected in previous studies, on the stress distribution at the vicinity of the plane-strain crake tipunder opening and in-plane shear loading conditions in the orthotropic materials is investigated in this paper. The influence of material properties and various loading and boundary conditions on the stress field patterns around a plane-strain crack tip in a orthotropic plate has been systematically investigated. The classification of analytically generated various crack tip stress field patterns in orthotropic plates as is done in this paper can be incorporated with the isotropic birefringent coating techniques to extract stress intensity factors more effectively. The distortions of angular distribution of the stresses around a crack tip are also studied systematically in terms of the rations such as σox/k₁, E y/E x and K u/K₁.
Han, Min Ku,Chung, Suk Choo 서울産業大學校 1991 논문집 Vol.34 No.1
It is attempted to develope a simple, reliable and cost-effective measuring device of the dynamic crack propagation velocity in nuclear pressure vessel steel (SA516 gr. 70). A relationship between instantaneous crack tip velocities and dynamic stress intensity factors for pressure vessel steels is estimated using dynamic crack propagation velocities determined by a proposed measuring device. The corresponding dynamic stress intensity factor vs. time history and the dynamic arrest toughness for each test are obtained using the generation mode dynamic finite element analysis. A function ?? which may be useful to predict the relationship between the dynamic fracture toughness and the dynamic crack arrest toughness for SA516 gr. 70 steel is suggested.