ABSTRACT
This article examines the methodology used in acoustic emission (AE) testing of structures such that we can improve this important application ofAE technology. Numerous successfulAE tests of structures have been completed, but details are quite often obscured for commercial reasons. Here, we attempt to organize the AEmethodology in four steps. 1.AESources: Primary sources of brittle fracture, micro-or macro-cracks, are distinguished from secondary sources of friction or fretting, rust, etc. The latter can be as important as primary ones in finding flaw. Materials effects are discussed separately. 2. Kaiser effects, arising from the irreversibility of AE, allow the detection of prior loading level and of damage states. 3. Source location: Using zone, 2D-and 3D-source location methods or via embedded waveguides, this approach identifies the area of integrity loss. 4. Source characterization: Many methods are practiced here, including combined AE parameters, attenuation-corrected signal amplitude, signal frequency, waveform analysis, pattern recognition analysis and moment tensor analysis. Avenues for better AE technology include: to accumulate basic data on structures with standardized procedures, to devise combinatorial approach between localized damage evaluation and long-range detection and to develop regional or global database under international cooperation. The final goal of determining the structural integrity is attainable only with systematic approach with damage quantification via NDT and with the use of fracture mechanics.
