Effect of interlaminar flaw on composite panel behaviour under acoustic loading

Abstract

A design of airframe structures has to be accompanied by material properties testing. Special focus has to be laid on high frequency fatigue behaviour. The acoustic fatigue test equipment for grazing wave’s incidence was designed based on the FE analyses. Flat composite panels were designed and manufactured using the Hexply 8552/AGP193-PW prepreg with different fiber lay-ups and with simulation of production imperfections or operational damage. Dynamic behaviour of panels was tested using three regimes of acoustic loading: white noise spectrum, engine noise spectrum and discrete harmonic frequencies loading. Rayleigh damping coefficients were evaluated for later use in FE models. Panel health was checked periodically through a power spectral density response on white noise signal. The ultrasonic NDT instruments were used for monitoring of relevant delamination increment. No increments of delamination were detected. The available acoustic power was below the fatigue limit of the tested structure.