Efficient Fracture Design for Complex Turbine Engine Components

Abstract

Many high-energy turbine engine components are fracture critical. However, the complex three-dimensional (3d) geometries and stress fields associated with these components can make accurate fracture analysis impractical. This paper describes a new computational approach to efficient fracture design for complex turbine engine components. The approach employs a powerful 3D graphical user interface (GUI) for manipulation of geometry models and calculated component stresses to formulate simpler 2D fracture models. New weight function stress intensity factor solutions are derived to address stress gradients that vary in all directions on the fracture plane.

Probabilistic Methodology for Life Prediction of Aircraft Turbine Rotors

“…A new method has recently been developed for modeling surface damage-related crack growth using results from 3D finite element analysis (McClung et al 2004, Waldhart et al 2004. It is based on the assumption that a Mode I crack propagates in the plane normal to the maximum principal stress (for the dominant stress pair in a given mission profile) in a region that is idealized as a rectangular plate.…”

“…Illustration of a new method for definition of surface damage-related cracks using 3D finite element results: (a) import 3D finite element model, reorient to display and select initial surface crack location (GUI automatically identifies principal stress plane), and (b) slice model along principal stress plane to reveal crack propagation plane and associated rectangular plate for fracture mechanics assessment (McClung et al 2004, Waldhart et al 2004. …”

Efficient Integration of Sampling-Based Spatial Conditional Failure Joint Probability Densities

“…Previous studies [6][7][8] have focused on modeling the spatial conditional failure JPDF as a multivariate histogram associated with regions within the domain that are referred to as "zones". The uniform probability density for each zone is set to the maximum possible value within the associated region to ensure a conservative value of F p .…”

Probabilistic Sensitivities for Fatigue Analysis of Turbine Engine Disks

“…As examples, though not exhaustive, the following input data have been developed: the frequency and probability distribution for the initial defect size of hard alpha particles in titanium [6,7], the constitutive properties of hard alpha defects [8], the crack growth rate in a vacuum for titanium [8], fatigue testing of the initiation of cracking for hard alpha defects [9], effects of residual stresses around hard alpha particles [10], the expected amount of variation in fatigue crack propagation scatter [11], and weight-function-based stress intensity factor equations for flaws under a bivariant stress field [12]. An FAA advisory circular has been issued that describes a probabilistic methodology and suggested input data to quantify the POF with respect to hard alpha defects [13].…”