Materials Science Forum, Vol.524-525, 77-82, 2006
Measuring and predicting the effects of residual stresses on crack propagation
This article presents the first part of a study on the interaction between residual stresses and crack driving force. Blunt notched CT specimens were pre-strained to introduce residual stresses at the notch, where a crack is subsequently introduced. FE modelling is used to model the specimen pre-load and pre-cracking. Modelling predictions are validated by two different methods. The total predicted surface residual strains are compared to image correlation measurements. The predicted residual strains were measured using neutron diffraction, both before and after fatigue cracking. The residual strain profiles show good agreement with the 3D FE model in the far field but the peak strains measured near the notch are smaller those predicted. This is a result of the low spatial resolution of the technique.
Keywords:pre-loading;blunt notched CT;image correlation;finite element;J-integral;crack driving force;neutron diffraction