A numerical study on the application of the Weibull theory to brittle materials

In this paper, the effects of assuming that a brittle material can be modelled by the two-parameter Weibull distribution, if the true representation of the material behaviour is actually a three-parameter distribution, are examined. It is shown that if data from a material characterisation test is used to predict the failure of a component and the stressed surface areas are very different, then this can lead to major discrepancies in the predicted failure stress. It is also shown that if the three-parameter model is a true representation of the material behaviour, then the Weibull modulus for the two-parameter approximation will vary with surface area.