SiC粒子強化複合材料における疲労き裂の発生および微小き裂の進展挙動

概要

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In this study, the small fatigue crack initiation and propagation behavior of A6061-T6 metal matrix composites reinforced with 20 vol.% SiC particles was investigated under cyclic axial loading at the stress ratio R of 0.1. The results obtained are summarized as follows. (1) The microscopy indicates that the fatigue cracks initiate preferentially at the sharp end of a particle in the matrix aluminum material, because the stress near the end of a particle appears to be much higher than the average stress. (2) The propagation behavior of small cracks (crack length 2c<150μm) was quite irregular. The crack propagation ceased at the end of a particle at some point of the loading cycle. This may be interpreted in terms of the connection of the main crack with the small second crack. (3) At Δσ=280 MPa, the relationship between dc/dN and ΔK_<eff> for small cracks (crack length 2c>150μm) is nearly identical to that for long cracks. It is considered that, due to crack closure, dc/dN of a small crack is greater than that of a long crack for the same ΔK.
一般社団法人日本機械学会の論文
1995-08-25