Validation Approaches for Weld Residual Stress Simulation

Abstract

In assessment of stress corrosion cracking behavior of susceptible welded materials, the contribution of weld residual stress is a key input for stress intensity factor calculations, which in turn are used to determine anticipated crack growth and to plan for inspection or repair. Without accurate weld residual stress information, it is challenging to develop an optimal plan for plant management. Weld residual stress simulations, based on non-linear finite element computations, provide a means to estimate residual stresses in components. However, there is no established, consensus approach for weld residual stress model validation, which could be used to judge model quality, specifically with respect to the influence of residual stress output on plant management decisions. A consensus model validation approach would benefit a broad range of stakeholders in pressure vessel technology.The paper provides technical detail of example approaches for weld residual stress model validation, and applies these approaches to a set of weld residual stress model outputs that were developed in the context of an industry round robin. The set of outputs is from Phase 2a of the international round robin organized cooperatively by the U.S. Nuclear Regulatory Commission and the Electric Power Research Institute. Example validation approaches include comparisons of output from one model with output from other models, as well as comparisons of model output with data from residual stress measurements. The figures of merit used for comparisons range from simple (e.g., evaluation of mechanical section forces) to complex (e.g., comparison of predicted crack growth behavior). Applying a range of validation approaches provides information for use within the technical community, to support development of a consensus approach for weld residual stress model validation.