應力擴大係數의 算定에 관한 연구: 光彈性解析을 中心으로

Abstract

In viewing of fracture problem of the structure by LEFM, SIF related with external force and crack state only has a important role. Firstly, stresses and displacements of the crack tip zone can be calculated from this value. Secondary, propagation of the existing crack can be discussed by comparing SIF with fracture toughness of the used material. In this paper, standard procedure calculating SIF from the photoelastic experiment was studied and accuracy obtained from the current usable experimental apparatus was discussed. Results obtained from a series of experiments could be summarized as follows. 1) On the photograph, isocromatic lines at the crack tip zone were inadequate to calculate SIF. That is, the shortest distances from crack tip to the isocromatic lines, fringe order N were distinguished from which were 2mm in case of reducing to prototype size. 2) A formula induced to calculate SIF from experimental results is valid only at the crack tip region. Therefore, there were some problems in using this formula to obtain SIF from current experimental results. 3) SIF at the crack tip obtained from extrapolation method in this experiments has shown 1% - 18% errors.