Statistical distribution and stress ratio dependence of fatigue life for injection molded short carbon fiber reinforced nylon composite

Bibliographic Information

Other Title
  • 射出成形カーボン短繊維強化ナイロン複合材料の疲労寿命の統計分布と応力比依存性


<p>The statistical distribution of fatigue life for a short carbon fiber-reinforced polyamide-6 composite and the effect of stress ratio on it are examined. A procedure for predicting S-N relationships for different constant values of probability of failure P, i.e. P-S-N curves, is proposed. Constant amplitude fatigue tests are first performed to obtain statistical samples of fatigue life at different stress levels and stress ratios (R = 0.1, 10 and R = χ = σUTS/σUCS), respectively. Static tensile and compressive strength data are also collected. To quantify the scatter of fatigue life, Weibull and lognormal distributions are fitted to the fatigue data obtained. The plot of fatigue data on a probability paper and the goodness-of-fit tests using the modified Kolmogorov–Smirnov suggest that both Weibull and lognormal distributions are acceptable as the distributions for the static strength data as well as the fatigue life data. The P-S-N curves at different stress ratios for different probabilities of failure (10%, 50% and 90%) are predicted for the two cases using the experimental data and using the anisomorphic CFL diagrams for different constant values of probability of failure, respectively, and they are compared to each other to evaluate the accuracy of the proposed theory.</p>



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