An Analysis of Sensitivity of the Monitoring System of Helicopters to Faults of their Blades

Results of a work on evaluation of the effectiveness of promising vibration diagnostic technologies on the basis of an operating helicopter with an experimental system for monitoring the state of structures are presented. To move towards a practical application of the monitoring system based on the Operational Modal Analysis (OMA), it is necessary to assess its ability to distinguish actual defects. This problem was solved in a practical way as applied to a composite blade rotating together with the rotor of an operating helicopter. To assess the effect of a defect on the modal properties of the blade, a numerical modeling was performed, where changes in two modal parameters, the frequency and shape of each of M modes, were calculated. The influence of a test defect was assessed by comparing the modal properties of the damaged blade model with those in its reference state. The defect model corresponded to the planned full-scale defect of the blade in the form of a through hole in its tail part. Based on simulation results, requirements to the system for measuring and processing data, as well as to conditions for conducting an experiment to assess the resolution of the system, are formulated.

Automated summary

The study evaluated the effectiveness of vibration diagnostic technologies on a helicopter, and monitored the state of structures with an experimental system. It was found that numerical modeling can assess the impact of defects on the modal properties of blades, when applied to a rotating composite blade.