Effect of constraints on stress intensity factor for dissimilar metal plate with centre crack under uniform tension

Abstract

Dissimilar metal joints (DMJs) are more common in the coolant systems of most of the engineering applications and are subjected to variety of loadings. To understand the constraint effect of the dissimilar metal welded joints (DMJs), fracture studies have been carried out on dissimilar metal plate (DMP) with center crack made up of ferritic steel (SA 508 Gr.3 Cl.1), austenitic steel (SA312 Type 304LN) and Inconel – 182 alloy (ENiCrFe-3). 2-D and 3-D finite element analysis (FEA) is carried out on the DMP with centre crack (length = 250 mm, width = 150 mm) for various crack lengths (15, 20, 30 and 50 mm) and various dissimilar metal welded joint widths (DMJWs) (5, 10, 20, 30, 40 and 50 mm) to evaluate stress intensity factor (SIF). SIF has been evaluated by employing domain integral method. It is observed from the studies that, (i) SIF increases with increase of crack length and DMJW, (ii) 3-D finite element analysis yields realistic SIF (iii) SIF of DMP reduces compared to homogenous plate, (iv) constraint effect is found to be significant if DMJW is less than the initial crack length, resulted in reduction of SIF (iv) constraint effect is found to be insignificant if DMJW is more than 20 mm and the ratio of crack length to DMJW is greater than 0.75. The study will be useful for damage tolerant analysis of structures/components which in turn will be helpful for repair, retrofitting of components and in-service inspection.