Stress Intensity Factors Due to Residual Stresses in T-Plate Welds

Abstract

Residual INTRODUCTIONIn this work, residual stress distributions in welded T-plates are presented. The stress distributions have been measuring using the neutron diffraction method, which determines the stress field directly from the measured elastic strains. A high strength steel (designated SE 702, equivalent to the A517 Grade Q steel) and a medium strength steel (BS EN 10025 Grade S355) have been examined. The former has a yield strength of 700 MPa and the latter has yield strength of 360 MPa. It has been found that the transverse residual stress distribution for different plate sizes and yield strength are of similar shape and magnitude when normalised appropriately and peak stresses are on the order of the material yield strength. The measured stresses are compared with the distributions provided in UK safety assessment procedures and the conservatism in the existing stress distributions is

A generic approach for a linear elastic fracture mechanics analysis of components containing residual stress

“…The values of f m (a/W) and f b (a/W) have been obtained by applying a unit membrane and bending stress respectively to the crack face. A similar approach has been used to obtain the stress intensity factor for surface cracked plates and the values obtained were almost identical to handbook solutions (see [5] for details). Figure 5 shows the solution for f m and f b for a T-plate and tubular Tjoint.…”

“…The stress intensity factors (SIF) have been obtained for T-plate and tubular T-joints using finite element (FE) analysis in conjunction with the superposition method as discussed in [5] and [9]. For the T-plate the width of the plate and the attachment are the same.…”

“…It was shown in [5] that for a sufficiently deep crack in a T-plate geometry the solution for a smooth plate can be used to determine the stress intensity factors. In this paper, however, solutions are presented for f m and f b which have been obtained from finite element analysis for the relevant geometry.…”

“…These include MMA welded T-plate specimens, fabricated with high strength ferritic steels SE702 [5] and medium strength low carbon ferritic steel BS EN 10025 S355 [10]. Measurements for welded joints and cold bent tubes [4] have been included to investigate whether it is appropriate to treat mechanical and repair weld-induced residual stresses in the same manner as the rest of the data.…”

“…Only the crack surface stresses need to be considered as the calculation of the SIF is based on the superposition principle [5,13]. The transverse residual stress is considered as the crack driving force and the Mode I SIFs have been evaluated using a path independent integral.…”