From the determination of first peak times of arrival, the location was determined from:
Location = (x/2)(∆t/∆t x )(1)
where x is the length between the outer sensors (25 mm). The location of each event after 130,000 s is plotted in Figure 7a versus the time of the test where the value 0 is the center of the gage section. Each **data** point represents a single event and the width of the **data** point is proportioned to the average AE energy of the given event. There are scattered and infrequent peak events for the over 70,000 s (~20 h) leading up to the heightened period of AE activity just prior to failure. The events at the end of the test are so dense that the period after 200,000 s (box in Figure 7a) are plotted in Figure 7b,c for the valley and peak events, respectively. Most of the peak and all of the valley events are concentrated in the 0 to +1.5 mm location from the center of the gage, which is where failure took place. Whatever occurred just prior to failure would not correspond to distributed matrix cracking along the gage length. Therefore, one would expect to observe localized damage near the fracture surface within an approximate 2 mm length or less of the composite, as shown below.