Mode II疲労き裂進展下限界値ΔK_<IIth>の測定(<特集>破壊力学)

概要

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In order to measure the Mode II fatigue crack growth resistance of various materials, a particular chevron notched double-cantilever type specimen with side grooves was designed. Mode II fatigue crack growth tests by using the newly designed specimens were conducted by a conventional closed-loop type tension-compression fatigue testing machine under a constant load amplitude which corresponds to the △K_<II>-decreasing test with increase in crack length. The crack length was measured by the AC potential method. The particular morphology of Mode II crack fracture surface was investigated. The distribution of shear stress in crack tip and Mode II stress intensity factor were analyzed using a FEM software, ABAQUS. The relationships between Mode II crack growth rate (da/dN) and △K_<II> for various materials were obtained, and the values of △K_<IIth> were determined. It was found that △K_<IIth> is larger than △K_<Ith> for all materials tested in this study.
2002-08-15