形状記憶 TiNi ファイバ強化複合材料での疲労き裂進展抑制

概要

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This paper describes the shape memory effect of TiNi fiber reinforced/epoxy matrix smart composite on enhancement of its mechanical properties, especially fatigue resistance. Fatigue crack propagation behaviors are investigated by using the originally developed method of fine-grid which was engraved on the epoxy resin surface by photo-etching. The effects of pre-strain value in TiNi fiber on fatigue crack propagation and then, the decreasing crack propagation behavior in the very local domain region around the embedded TiNi fiber are investigated in detail by using fine-grid method. The retardation of fatigue crack propagation is attributed mainly to the compressive stress field in the matrix due to shrinkage of the prestrained TiNi fibers above A_f temperature. The local crack retardation at the interface region very near the TiNi fiber is experimentally confirmed by the change of local crack tip strain behavior. From crack-tip strain hysteresis in one load cycle, the compressive stress induced in the matrix and following fatigue crack closure phenomena play a key role to suppress the crack tip stress intensity and these fatigue crack propagation retardations. The comparison between the theoretical prediction and experimental results also is discussed.
社団法人日本機械学会の論文
2001-11-25