Impact detection for a fiberglass composite rotor blade

Abstract

In this paper, amethod is presented for impact identification that uses limited sensor application to characterize an unknown impact's location and force amplitude upon an operational composite helicopter blade and to determine the errors associated with the use of static frequency data for impact identification in rotating bodies. There have not been prior investigations into the use of limited sensor application or the error associated with using static frequency data for impact characterization in rotating bodies. Analytical modeling demonstrates that errors in estimated impacts due to centrifugal stiffening occur at the resonance and antiresonance frequencies of a rotating blade. The impact characterization method is shown to estimate the correct location of an impact 50%, 92%, and 99% with an average force estimate error of 4.6%, 4.6%, and 2.5% for symmetric, asymmetric and full-sized composite helicopter blades, respectively. © 2014 The American Helicopter Society.