Stitched/Resin Film-Infused (S/RFI) composites have been identified as low-weight and costeffective materials. However, the application of S/RFI composites in aircraft yield more challenges to aircraft designers due to a lack of understanding failure mechanisms and the damage tolerance of composite systems. This can be accomplished by conducting a damage tolerance evaluation based on finite element method enhancement and multi-scale Progressive Failure Analysis (PFA) for the design of stitched/resin film-infused S/RFI composite structures containing Discrete Source Damage (DSD) sites. A computational approach is developed to predict Durability and Damage Tolerance (D&DT) by PFA in composite S/RFI stiffened panels under DSD. This D&DT approach is implemented by integrating composite mechanics, finite element analysis, and damage progression tracking algorithms [Ref 1]; a part of NASA Advanced Composite Technology (ACT) project. Validation of our approach, [Ref 2] compares the test measurements of 3-stringer test panels. These panels were divided into tension and compression categories with saw-cut and diamond shape slot configurations. 3-stringer test panel models were built and analyzed to determine damage modes and their locations, critical failure events and failure loads. Damage propagation and crack turning were fully monitored to produce a predicted structural performance. Results show that load-displacement curves were consistent with the experimental test observations. Additionally, the crack turning phenomena was observed, as a design practice; when skin and stringer height and width are of certain ratios.
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