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ABSTRACT--A method to determine weak or defective bonding areas within the brazed adjoining contact surfaces of composite ceramic-metal plates is proposed. The plates include voids, as well as hairline cracks in the ceramic layer, caused by the high-temperature brazing process. To detect these flaws, transient ftexural waves are generated and transmitted through the plate by means of an attached piezoelectric transducer. These pulses are a narrow band signal generated in the time domain. The characteristic wavelengths corresponding to the narrow frequency spectrum may be larger than the size of the flaw. Dynamic holographic intefferom-. etry using a double-pulsed twin-cavity Nd:YAG laser, comprising two independent reference beams, was used to measure the response. The experimental interferograms (phase maps) coincide rather precisely with analytic results derived I from Mindlin's plate equations (including effects of shear and rotary inertia).

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