Adaptive Estimation Methodology for Helicopter Blade Structural Damage Detection

A new, multiple model approach for detection and identie cation of structural damage in a rotating helicopter blade is presented. A full-scale rotor analysis using a detailed model of the hingeless blade elastic behavior and dynamics is carried out. Several stiffness damage levels and locations are considered, and a set of Kalman e lters is constructed accordingly. The best e tting model is determined in a probabilistic manner. Because the new method is model-based, the need for a training stage is eliminated, and a wide range of e ight regimes can be handled. Moreover, process and measurement noises are treated inherently, contributing to the superiority of the method over previously published related methods. A Monte Carlo simulation study is used to provide a comprehensive analysis of the statistical nature of the method. Single-blade analysis results demonstrate excellent identie cation capability and good damage detection in the presence of a relatively high level of noise. The case of damage located near the blade’ s root combined with a sensor near the tip produces a high damage identie cation probability. In less detectable cases, such as damage located in midspan, a simple statistical procedure enables achieving a high detection probability along with a low false alarm rate.