Ceramics-Silikáty 54, (1) 72 - 77 (2010)

The article deals with results of our experimental study focused on new methods of nonlinear ultrasonic spectroscopy for detection of structure integrity damage in ceramic material usage. The tested samples are excited by harmonic ultrasonic signals. In case of cracks presentation in the material structure they cause strong nonlinear dynamic effects accompanying the elastic waves propagation which can be demonstrated by occurrence of new harmonic components in the response spectra. The frequency spectral analysis of the sample response enables us to identify the damaged material structure. Two methods were applied: method with one exciting harmonic ultrasonic signal and the second method with two exciting harmonic ultrasonic signals. There were analyzed undamaged specimens and also specimens containing defects of cracks type. Intact specimen measurement results proved that non-homogeneity of ceramic material is not source of nonlinear effects accompanying elastic waves propagation. Dynamic material response of samples with damaged material integrity was demonstrated by formation of new frequency components in the response frequency spectra. For experimental verification of these methods we used ceramic cladding elements from secondary materials and ceiling slabs, and that is why they can be used for testing structure integrity of ceramic materials.