Fatigue Design Model Based on Damage Mechanisms Revealed by Acoustic Emission Measurements

Abstract

Integration of the microcomputer into acoustic emission instrumentation has brought AE monitoring of fatigue tests into the realm of practicality. On-line processing makes available a selection of software tools, enhancing classical techniques for eliminating the background noise which usually blanked out the desired data. Fatigue tests monitored for acoustic emission were carried out at room temperature on Incoloy 901 material specimens, over a stress-ratio range of -1 < R < .2. Valid AE data were obtained even when the load cycle passed through zero. The AE data permitted specific identification of the various phenomena occurring on the way to final failure. These included initial plasticity, crack nucleation and propagation phases. The AE findings were supported by microscopic examination. Based on the experimental data, a preliminary damage-prediction model was formulated.

Modifications and Statistical Analysis of Acoustic Emission Models Based on the Damage and Fractal Characteristics

“…Many efforts [1][2][3][4] have verified and identified the AE source mechanisms. Among them, the research on acoustic emission mechanism and acoustic emission characteristics based on micromechanics theory has always been paid more attention by researchers.…”

Deterministic and probabilistic fatigue prognosis of cracked specimens using acoustic emissions

“…The advantage of AE compared to other monitoring techniques like the use of only strain gauge measurements resides in the fact that AE allows the detection and monitoring of cracks without the need of prior knowledge of the load history, empirical information like the S-N curves, or even a finite element model. Furthermore, the proposed techniques that use AE in conjunction with strain gauge measurements have the potential for assertive prognosis of fatigue life, because AE can be related to the actual crack length and the number of cycles (calculated from strain gauge measurements) as shown by different researchers [12][13][14][15][16][17][18]. AE has been used for the monitoring of bridges since the 1970s.…”

Basic study on crack diagnosis of rotary equipment by fluid-mediated AE method

“…In an example of AE occurring during a tensile fatigue test of a steel material (D. Fang and A. Berkovits, 1995), it was reported that an AE signal is more likely to occur in the region immediately after the start of the test, after which the AE signal decreases. Then, before the shaft breaks, the AE signal occurs frequently.…”