THE ULTRASONIC IMPULSE-RESPONSE OF UNIDIRECTIONAL CARBON-FIBER LAMINATES

The impulse response of undirectional carbon fibre reinforced polymer laminates has been determined, using a pulsed laser to generate the im pulse and a broadband capacitance transducer to detect the normal comp onent of surface motion. Waveforms were recorded at a series of positi ons along lines both parallel and perpendicular to the fibre axis. Vel ocity profiles of major arrivals have been determined, and shown to co rrespond to the expected group and phase velocities for the quasi and pure bulk-wave modes respectively. The elastic stiffness constants for the material have been calculated using measured phase velocity surfa ces for pure modes and the reconstructed phase velocity surfaces obtai ned from measured group velocity data for quasi-modes.