The sensitivity of a Weibull failure criterion to singularity strength andlocal geometry variations

Previous experimental evidence has shown scale sensitivity of adhesives bot h in terms of ultimate stress and strain to failure; this sensitivity may b e modelled using Weibull statistics. The implications of this on the sensit ivity of strength predictions to mesh density around singularity points and small changes in local geometry is investigated using an idealised model o f an enclosed corner in an adhesive joint. The sensitivity of two other fai lure criteria are also compared to the Weibull method. It is seen that ther e is a critical relationship between the Weibull shape parameter, m, and th e singularity strength, lambda. This relationship marks the transition betw een mesh insensitivity and mesh sensitivity, even with a singular stress (o r strain) held present. If the singularity is removed by localised rounding , then the Weibull method of failure prediction shows much less sensitivity to the exact local geometry variation than other methods of failure predic tion. (C) 1999 Elsevier Science Ltd. All rights reserved.