Probabilistic Fracture Mechanics for Mature Service Frame Rotors

Abstract

Large gas turbine design and service business are challenged with increased demands toward flexible operations, increasing number of start-stop cycles, and intermediate cycles. Probabilistic fracture mechanics simulation design tools have matured and became robust and reliable. We present a probabilistic reevaluation of Siemens E-class turbine disks by the combination of probabilistic two-dimensional axisymmetric part analysis of the disk and a novel probabilistic approach for the three-dimensional blade attachment. The first addresses the risk of inherent forging flaws, the latter combines the risk of surface crack initiation, growth, and failure. Both models consider the heterogeneous nature of material properties, flaw geometries, and detectability. These novel concepts developed at Siemens allow for an optimization of resource usage and safety, as well as the development of new service and inspection concepts for a variety of service frames and classes.