Stitched/Resin Film-Infused (S/RFI) composites have been identified as low-weight and costeffectivematerials. However, the application of S/RFI composites in aircraft yield morechallenges to aircraft designers due to a lack of understanding failure mechanisms and thedamage tolerance of composite systems. This can be accomplished by conducting a damagetolerance evaluation based on finite element method enhancement and multi-scale ProgressiveFailure Analysis (PFA) for the design of stitched/resin film-infused S/RFI composite structurescontaining Discrete Source Damage (DSD) sites. A computational approach is developed topredict Durability and Damage Tolerance (D&DT) by PFA in composite S/RFI stiffened panelsunder DSD. This D&DT approach is implemented by integrating composite mechanics, finiteelement analysis, and damage progression tracking algorithms [Ref 1]; a part of NASAAdvanced 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 diamondshape slot configurations. 3–stringer test panel models were built and analyzed to determinedamage modes and their locations, critical failure events and failure loads. Damage propagationand crack turning were fully monitored to produce a predicted structural performance. Resultsshow that load-displacement curves were consistent with the experimental test observations.Additionally, the crack turning phenomena was observed, as a design practice; when skin andstringer height and width are of certain ratios.
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