Broadband nonlinear elastic wave modulation spectroscopy for damage detection in composites

A non-destructive testing procedure is proposed for damage detection in composites using full wavefield measurement obtained a scanning laser Doppler vibrometer. Vibrations are excited two low-power piezoelectric actuators leading to nonlinear elastic wave modulation at the defect. One actuator supplied with broadband chirp signal and other single-frequency sine signal. First, time–frequency filtering method extract specific components of interest (e.g. second higher harmonic first sideband) without need multiple excitation sequences. Next, maps constructed bandpower calculation filtered components. It demonstrated that sidebands provide an exclusive imaging defect nonlinearity, not affected by potential source nonlinearity. The map construction applied various carbon fiber reinforced polymer test specimens different features: (1) coupon quasi-static indentation damage, (2) artificial delaminations, (3) bicycle frame impact (4) stiffened aircraft panel partially debonded stiffener. results indicate high performance developed types curved and/or