The influence of singular field dominance on the caustic methods

The caustic method as applied to fracture mechanics for measuring the stress intensity factor, contains several approximations which limit its applicability and accuracy. The accuracy of the caustic method for the determination of the stress intensity factor is based on the restriction that the K-dominant singular field is fully established at which the experimental data are taken. In this paper, we attempt to identify the regions in which experimental measurements by caustic methods can be performed with confidence. The reliability of the method of caustics applied to the static problem and the case of a stationary crack subjected to dynamic loading are investigated in detail. The results demonstrate that significant deviation can occur in the determination of the stress intensity factor from shadow spot measurements. Conclusions regarding the method of caustics in the determination of the stress intensity factor are extracted from these results.