The set-up for AE acquisition was such that the parametric **data** (load and strain) were acquired every second in addition to the AE waveforms. Thus, the variation in stress for a given fatigue cycle was not possible for the 1 Hz data. However, for the 0.1 Hz and 0.01 Hz tests, enough load **data** were available to discern at which point of the cycle the events were occurring. The AE analysis for the 0.1 Hz test (113-3) are presented here in detail, which showed the enhanced AE activity near failure ( Figure 2b). The features found for the 0.1 Hz test were also observed for the 1 Hz tests (147-3 and 113-9) for the most part. Although both specimens were tested at 1 Hz, the same acquisition rate for load in the software, the peak and valley events could be discerned by the timing of the event. In other words, the peak and valley events occurred approximately 0.5 s from one another. Where there were differences is discussed below. The AE **data** were separated into events which occurred near the peak of the cycle and events which occurred near the valley of the cycle. Figure 3a shows the cumulative AE energy **data** for the overall test as well as the contributions of energy for the peak and valley. There were no valley events until the 201,990 s (56.1 h) mark of the test, 2.4 h prior to failure. After the occurrence of valley events, most of the AE energy was dominated by what occurred during the valley part of the stress-cycles with some appreciable AE occurring during the peak of the cycle as well. An example of when the valley and peak events occur in a stress cycle is shown in Figure 3b for the cycle centered at 210,001 s. Note that "valley" events occur during unloading as the valley is approached and "peak" events occur upon loading as the peak of the stress-cycle is approached. with some appreciable AE occurring during the peak of the cycle as well. An example of when the valley and peak events occur in a stress cycle is shown in Figure 3b for the cycle centered at 210,001 s. Note that "valley" events occur during unloading as the valley is approached and "peak" events occur upon loading as the peak of the stress-cycle is approached.