Probabilistic Design of Damage Tolerant Rotorcraft Components

Abstract

In an effort to improve the reliability and reduce the operating costs of helicopters, an increasing emphasis is being placed on the development of a damage tolerant methodology for the design and analysis of rotorcraft structural components. Because of the larger uncertainty associated with rotorcraft usage, initial defect distribution, crack growth model, detectable crack size for a given inspection technique, and critical crack size at limit load, a probabilistic approach has to be used to systematically account for system uncertainties. To form a risk-based optimal inspection/repair decision tool for damage tolerant rotorcraft components, a probabilistic risk analyzer, PROGRAW, is developed by integrating the Component Object Model (COM) server version of AFGROW with the Monte Carlo simulation shell code within the Visual Basic for Application (VBA) development platform. The Monte Carlo simulation module, the post-statistical analysis module and the response sensitivity analysis module at a given design life are embedded in the VBA platform through their corresponding Dynamic Link Libraries (DLLs). The applicability of PROGROW is demonstrated via numerical examples.