This effort will focus on developing effective tools enabling automatically building structured finite element (FE) mesh for as-built composite parts from X-ray Computed Tomography (CT) scan data that accurately captures performance-critical flaws in the form of the manufacturing defects. Such tools will fill a major technology gap in analysis-based assessment of residual capability and remaining useful life of composite aircraft flight-critical components and structure including assessment of quality of a repair. The inability to capture performance-critical flaws and their effects are among the most urgent needs of composite aircraft certification and sustainment. Although FE modeling represents a generally accepted practice for structural analysis, tools for generating the mesh reflecting as-built material structure of composite parts and repairs are not available, and therefore engineers are faced with a challenge of comparing CAD models or drawings of composite structure to CT scan data and manually introducing discrepancies into finite FE mesh. Geometric complexity of the flaws with a priori unknown effect has been preventing effective manual meshing. Converting the CT scans into FE mesh will provide the means for analysis-based assessment of the effects of manufacturing defects with a large span of severity/sizes in complex composite structures; and for developing repairs. The proposed solution shall address the following key requirements: (A) The ability to generate accurate subsurface geometry data for a composite structure that includes all manufacturing defects such as wrinkles and voids at ply interfaces. (B) The ability to automate the conversion of the CT scan-based geometry data to structural FE models revealing the effects of these defects on strength and fatigue performance for safe repairs, life-extending design changes, and disposition instructions. The FE mesh must be applicable to progressive damage and failure analysis of the laminated composite structure including manufacturing defects. This project will merge state of the art nondestructive measurements with composite durability and damage tolerance analyses into an add-on toolkit package for a commercial FE software program. The software toolset for rapid FE mesh generation of as-built composite parts and repairs will address a major gap in the structural diagnostics including free of human factor interpretation the nondestructive measurement data enabling the safe and cost-effective part disposition decisions. Phase I effort will demonstrate a semi-automated transition of CT-based measurements of a rotor blade section or wing section to a high-fidelity FE mesh that captures the composite material structure including ply-orientations with a refined 3D mesh including manufacturing defects.
