応力比の影響を考慮した一方向繊維強化複合材料の現象論的疲労モデル

概要

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A phenomenological fatigue model for describing the effect of stress ratio on the off-axis tensile fatigue behavior of unidirectional fiber-reinforced composites has been developed. First, empirical fatigue parameters are briefly reviewed. The conventional strength ratio is useful in manipulating the directional nature of the off-axis fatigue strengths. Using a modified strength ratio that considers the effect of stress ratio, we can substantially remove both the off-axis angle dependence and the stress ratio dependence of the off-axis T-T and T-C fatigue data, and obtain a master S-N curve which is almost independent of the off-axis angle and stress ratio. The modified fatigue strength ratio is then generalized in terms of the non-dimensional effective stress that corresponds to an extension of the conventional strength ratio. By using the modified non-dimensional effective stress, the fatigue damage mechanics model proposed in the previous study is further extended to cope with both the off-axis angle dependence and the stress ratio dependence of the off-axis fatigue strengths. The capability of the proposed fatigue model to reproduce the off-axis S-N relationships for different stress ratios is demonstrated through comparisons with the experimental results on unidirectional glass and carbon fiber-reinforced polymer matrix systems.
一般社団法人日本機械学会の論文
2003-03-25