Modal Parameter Identification and Damage Localization of Composite Helicopter Rotor Blades Based on AR/PR Identification

Abstract

The structural characteristics and application background of helicopters determine that the primary dynamic components work in environments with high cyclic amplitude and low-stress vibration fatigue load. As the most critical structural system of helicopters, structural health monitoring of the rotor blades is necessary to avoid fatigue damage under working conditions. Modal parameters, as functions of the physical properties of structural systems, change when there is damage or internal defects (the mass, stiffness, and damping of the structure will change). This article completes the identification of modal parameters of composite rotor blades under working conditions based on operational modal analysis (OMA). Specifically, using the AR/PR (autoregressive/polyreference) time-domain identification method, experiments are designed to identify the modal parameters (natural frequency, modal damping ratio, and mode shape) of composite rotor blades based on acceleration and strain signals. The results of the identification of modal parameters are verified through finite element simulation and modal measurement experiments. In addition, the application of OMA for the location of composite rotor blade damage is also studied.