Three-Dimensional Nonlinear Structural Analysis Methods for Gas Turbine Engine Metallic Components and Component Assemblies

Air Force engines are required to satisfy both safe-life and fatigue crack growth (damage tolerant) design criteria under the engine structural integrity program (ENSIP). To achieve this requirement, nondestructive inspection techniques are used to detect cracks that can potentially grow to failure within the next inspection interval. However, these nondestructive inspections cannot be performed on wing and require a complete disassembly. Hence, the current life management approach is time consuming and expensive. Phase I will demonstrate feasibility for a three-dimensional nonlinear analysis method for advanced engine prognosis. The proposed methodology will include three dimensional crack growth in components and assemblies of components, non-linear material behavior, surface-treatment induced residual stress effects, and complex mission loading, coupled with detectable sensor parameters. The computational methods will be consistent with a probabilistic prognosis system and the design system developed for JSF. The approach will use engine sensor data acquired by the engine control and incorporate an analytical transfer function to obtain the instantaneous damage state. The resulting damage state will then be used to derive the remaining component durability.