Integration of Networks of Sensors and Electronics for Structural Health Monitoring of Composite Materials
Table 5
Material with and without integrated inclusions: stress, amplitude, and frequency range of the first acoustic events, and their classification. The lower and upper limits of each range are the lower and upper values observed among all the experiments conducted. Only the events in a stress window of about 20 MPa have been considered. Results from laminates [16] are here reported for comparison.
Lay-up
Stress range of first AE events (MPa)
First AE Events Amplitude range (dB)
Peak Frequency of first AE events (kHz)
Event type classification based on micrographic inspections
Blank Samples
320–400
35–60
100–180
Matrix microcracking, fiber pull-out
Sample with device
89–106
50–75
150–300
Matrix micro-cracking at the sensor interface, debonding events
Blank Samples
33–43
40–50
130–170
Matrix micro-cracking, debonding,
Sample with device
10–14
43–65
150–350
Matrix micro-cracking at the sensor interface, debonding events, friction
