Studies on the primary statistics and signal analysis of the acoustic emission during the propagation of cracks in fracture mechanical samples

As is demonstrated by the experimental results, the method of acoustic emission testing is well suited to obtain information on the statistical-microscopic material behaviour of fracture mechanically loaded materials before and during the propagation of cracks. So this method closes the gap between the on-line determination of macroscopic parameters (stress, volume enlargement, etc) and the microscopic observations which can only be performed after the material test. Based on different models, the fundamental processes of acoustic emission are presented to determine their influence on the experimental measurements. In addition models are presented for stable and unstable crack propagation. The most essential result of this work is a demonstration of a hitherto unknown interrelation between amplitude and time statistics. (orig./RW)