A NUMERICAL AND EXPERIMENTAL-STUDY ON DEFECT ASSESSMENT OF PLAIN AND WELDED BARS WITH SHALLOW CRACK GEOMETRIES

Several fracture mechanics based models are currently available for de fect assessment. These models generally assume that any defects presen t in the structure are located in materials of uniform properties and make no provision for the possible differences in deformation behaviou r of components fabricated with dissimilar material. Extensive researc h using numerical simulation has been carried out for a number of year s at University College of Swansea to investigate the effects of weld mismatch on potential fracture behaviour. However, no detailed validat ion work has been done to verify the large amount of data generated so far. The work presented in this paper was aimed at filling this gap. Crack tip parameters of single edge notch specimens under pure bending and direct tension were studied using a combination of experimental a nd numerical techniques. The results of this combined study confirm th e validity and accuracy of the numerical procedure used. Comparison of the values of CTOD and J-integral with those obtained using the defec t assessment models shows that these models are not adequate even for predicting behaviour of homogeneous specimens. Much research is theref ore still required to develop procedures for accurate predictions.