High-energy rotating components of gas turbine engines may contain rare material anomalies that can lead to uncontained engine failures. The Federal Aviation Administration and the aircraft engine industry have been developing enhanced life management methods to address the rare but significant threats posed by these anomalies. One of the outcomes of this effort has been a zone-based risk assessment methodology in which component fracture risk is estimated using groupings of elements called zones that are associated with 2D finite element (FE) stress and temperature models. Previous papers have presented processes for creation of zones either manually or via an automatic algorithm in which zones are assigned to each finite element in a component model. These processes may require significant human time and computer time. The focus of this paper is on the optimal allocation of multiple finite elements to zones that minimizes the total number of zones required to compute the fracture risk of a component. An algorithm is described that uses a relatively coarse response surface method to estimate the conditional risk value at each node in a finite element model. Zones are initially defined for each finite element in the model, and the algorithm identifies and merges zones based on minimizing the influence on component risk. The process continues until all of the zones have been merged into a single zone. The zone sequence is applied in reverse order to identify the minimum number of zones that satisfies component target risk or convergence threshold constraints. This solution provides the optimal allocation of finite elements to zones. The algorithm is demonstrated for a representative gas turbine engine component. The approach significantly improves the computational efficiency of the zone-based risk analysis process.

This content is only available via PDF.
You do not currently have access to this content.