The influence of residual stresses on fracture behavior of Pipe Ring Notched Bend specimen (PRNB)

This paper focuses on analysis of the influence of residual stresses on the fracture behavior of PRNB specimens, with the aim to estimate the differences in fracture behavior of PRNB specimens with and without the residual stresses. The residual stresses are estimated experimentally for four different pipe types by using three methods: incremental hole drilling method, X-ray diffraction, and Splitting method. In order to estimate the influence of residual stresses on the fracture behavior of the newly proposed PRNB specimens, there are load-displacement curves obtained experimentally and numerically and then compared. In order to obtain more detailed analysis of residual stresses' influence, J - integral versus thickness of the specimen curves are presented for the specimen with and without residual stresses and for various loading pin displacements. Obtained results show a very good correlation between experimentally and numerically obtained load-displacement curves. The J - integral analysis leads to the conclusion that residual stresses do not have significant influence on fracture behavior of PRNB specimens made from investigated pipes.