残留応力場の疲労き裂進展速度の予測 : き裂面部分接触の考慮

概要

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The introduction of a superposition technique makes it possible to evaluate the effects of residual stress on fatigue crack growth characteristics. Under compressive residual stress, however, the classical method sometimes yields to an overlapping of the crack surfaces, which is physically unacceptable. A more careful estimation procedure is now desired. In this study, the validity of a method incorporating the partial crack surface contact was confirmed to account for the effect of residual stresses. When the crack surfaces are fully closed at minimum stress intensity, K_<min>, the conventional supperposition technique gives the same results as this method. On the other hand, when partial crack surface contact occurs at K_<min> with the original crack tip open, the conventional technique gives an unconservative prediction of the actual crack growth rates. It is shown that the physically acceptable solution adopted here should be used in the latter cases.
1988-02-25