An experimental investigation into the operational safety of a welded penstock by a fracture mechanics approach

Abstract

Abstract—Three different fracture mechanics approaches were applied to two full‐scale penstock model tests. The two models were produced, using a Sumiten 80P HSLA steel (minimum yield strength 700 MPa and minimum ultimate tensile strength 800 MPa), in the form of pressure vessels. The first experiment was a burst test performed on a pre‐cracked model to determine crack arrest properties. The second experiment was a hydro‐pressure test on a model with no cracks and this enabled a post‐yield experimental analysis of the undermatched weld metal, when cracks did not initiate. Crack driving forces, obtained numerically, and J‐R curves, obtained by the J‐integral direct measurement on tensile panels, were used to predict the residual strength. The overall behaviour of a welded penstock under load was analysed on the basis of the results of these three approaches, allowing an evaluation of the significance of cracks.