Critical length measurements in carbon fibres during single fibre fragmentation tests using acoustic emission

In this work, a single T300 high strength carbon fiber filament (7μmdiameter)was embedded in three different polymeric matrices (polycarbonate, polyurethane and epoxy). A total number of fifteen dog-bone specimens, five per matrix, were prepared, each with total length 45 mm. Tests were performed in displacement control mode with a crosshead speed equal to 0.13 mm/min. During these tests, acoustic emission was continuously monitored using pairs of piezoelectric microsensors (5 mm diameter), resonant at 300 kHz, placed at a mutual distance center-to-center of 30 mm, each 15 mm from the middle of the sample.