The rotorcraft industry lacks a validated analysis tool that would enable designers to use composite bonded joints in primary structures. The overall goal of this program is to develop such a tool by combiningstate-of-the-art analysis methods with an extensive test database in order to generate certifiable strength and fatigue life predictions ofrotorcraft joint configurations and loading conditions. For Phase I and Phase I Option, NSE Composites Stress Services (NSE) is teamed withmembers of the rotorcraft industry (Bell, Boeing Helicopter, and Sikorsky) to identify candidate joints that have potentially high payoff as bonded joint redesigns. NSE and its research consultants will conduct state- of-the-art strength and fatigue analyses on selected configurations. NSE's hybrid analytical approach is based on a strength-of-materials approach to determine damage initiation, and a fracture mechanics approach to assess damage progression. Accumulation of damage due to fatigue spectra will also be predicted. The Phase I and Phase I Option results will be: a detailed definition of candidate joints, a preliminary evaluation of the selected analytical approach, a preliminary Phase II test matrix, and a flowchart of the software to be developed in Phase II.
Benefits: The benefit of a validated analysis tool for composite bonded joints is higher efficiency, lower cost composite structural designs. The initial commercialization will be aimed at the rotorcraft industry. As the analytical approaches are validated over a wider range of configurations, the tool will have general aerospace application.
