Use of Weibull statistics to quantify specimen size effects in fatigue of GRP

Abstract Data are presented to show that changing specimen size has a considerable effect on the fatigue life of unidirectional GRP. As the volume of material under stress is increased, the probability of the existence of a severe defect also increases and so the expected fatigue life will decrease. Weibull statistics are used to calculate the magnitude of this effect, and the predictions tested against the experimental data. Within the limits of its accuracy, the model was found to account for the observed differences in the fatigue lives of specimens and large sections cut from components, in most situations.