We propose the development of a validated analysis tool to predict damage growth and useful life of loaded fastener holes in laminated composites. The objectives of Phase I are (1) to develop and verify a concept for comprehensive damage initiation and growth models applicable to loaded fastener holes; and (2) define a conceptual design for a prototype software/tool to perform damage growth and life prediction for loaded holes in composite laminates. The Numerical Technology Company team accumulated significant expertise and experience in the durability and damage tolerance technology development for composites and demonstrated unique abilities to predict damage and useful life through the rotorcraft industry verification. The team members developed a methodology for measurement of key matrix-dominated material properties as well as developed finite element-based techniques enabling accurate failure predictions for composites under quasi-static and fatigue loading. The proposed effort will further expand and verify/validate the durability and damage tolerance technology for loaded fastener holes in composites and establish a basis for the implementation of the algorithms in commercial software.
Benefit: The comprehensive durability and damage tolerance technology will enable cost-effective design optimizations for new composite parts as well as design modification and repair of existing components to extend service life, reduce maintenance costs, and extend operational capabilities of air, marine, and ground structures. The developed software will enable the assessment of the optimal combination of useful life and performance characteristics without costly experimental iterations. This software will promote the use of various design and manufacturing processes beyond the current limits of high value-added composite applications where high-cost empirical optimization could be accommodated. It will also improve the fatigue life substantiation capabilities for existing components through capturing the effects of various defects and damage introduced during manufacturing and service.
Keywords: Composites, Composites, fastener holes, FEM, Fatigue, Damage
