Abstract
The present paper reports the possibility of the acoustic emission (AE) application from the results of the testing performed at NASDA (National Space Development Agency of Japan) on H-I rocket motor nozzle holders (Graphite/Epoxy composites), such as materials tests, the burst test and the hydroproof test. Amplitude distribution during tests shows three types of the fracture mechanism, such as fiber breakage (over 70 dB), delamination (between 60 and 70 dB) and matrix cracking (under 60 dB). After the middle stage of the burst test, AE event rate is shown a saturated behavior, and a large scale delamination is observed in the fracture surface. The upper limit speed for data acquisition (40 events/s) of AE equipment (3000/3104: PAC) underestimated the number for middle amplitude events of the delamination. During the hydroproof test, both large amplitude events and large number of AE events are detected in spite of the higher threshold (+20 dB) than that of the burst test. The strain gages on the hydroproof sample indicate higher strain than that of the burst test. Both AE and strain results show that the hydroproof test sample would have bigger damage than the burst test sample.
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