An experimental and numerical study of the fracture behaviour of tubular specimens in a pin-loading-tension set-up

Abstract

Evaluation of a valid crack tip loading parameter using standard ASTM practice may not be feasible in many situations, e.g. in thin tubular specimens with diametrically opposite axial through-wall cracks (loaded in opening mode) that are obtained from zircaloy fuel pins of nuclear reactors. Recently, a pin-loading-tension (PLT) experimental set-up has evolved for this purpose. However, the required geometry functions (which should be obtained from a three-dimensional (3D) finite-element (FE) analysis procedure) for evaluation of the stress intensity factor (SIF) for such a set-up is not available in the literature. In this work, a detailed 3D FE analysis of the PLT set-up has been carried out where both the pin and the mandrel have been modelled. Analysis has been carried out for the full loading path (i.e. for applied displacements beyond the limit load of the specimen) in order to demonstrate the effectiveness of the model and the results have been compared with those of the experiment. In addition, the SIFs (and geometry functions) of the PLT set-up (with different initial crack lengths) have been evaluated from the FE results using extrapolation techniques and were compared with the results from two different analytical techniques.