Nondestructive evaluation of ceramics using impact-acoustic response measurement
Advanced ceramics are being proposed as the material to take us into the 21st century. Although advanced ceramics have special attributes, they are very brittle. Defect location and characterization therefore become a critical issue in their successful application. Industry and government have a continuing interest in developing new and improved methods of nondestructive evaluation (NDE) of the integrity of materials and structures in order to detect the existence of cracks and other defects in ceramic materials. Digital signal processing (DSP) has been playing an increasingly important role in improving NDE techniques. In this thesis, an impact-acoustic response technique is used to characterize the dynamic properties, natural frequencies and damping factors, of silicon carbide (SiC). Several digital signal processing, fast Fourier transform (FFT), filtering, and chirp z-transform (zoom) techniques are combined to provide an efficient and accurate NDE measurement method. Computer simulations are presented to demonstrate the ability of DSP to increase the sensitivity and reliability of a very simple and often- used impact-acoustic response technique. Experimental results conducted on silicon carbide modulus of rupture (MOR) bars are presented.