PSI - Issue 50

S. Lobanov Dmitriy et al. / Procedia Structural Integrity 50 (2023) 163–169 Lobanov Dmitriy S. et al./ Structural Integrity Procedia 00 (2022) 000 – 000

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Fig. 4. Fiberglass STEF specimens surface microstructure before and after thermal and moisture aging in seawater in an unloaded state (before testing).

3.2. Acoustic emission testing The results of the damage accumulation and destruction processes analysis of structural fiberglass composite after preliminary thermal and moisture aging in process water, seawater and machine oil at different durations and temperatures based on the registration and processing of acoustic emission signals are obtained. Diagrams of the peak amplitude AE signal distribution and graphs of the cumulative energy of AE signals dependence on time for fiberglass samples aged in different environment have been obtained and analyzed. Earlier publications noted that the growth of cumulative energy reflects the defects' accumulation in the structure of the material under loading [Lobanov et al. (2019)]. The effect of duration, temperature, and environment on the processes of damage accumulation in materials is described. The diagram of the peak amplitude AE signals distribution for fiberglass samples aged in machine oil, seawater , process water and for a sample without aging is shown in figure 5, a. Sample distributions are similar. It can be seen that signals with a peak amplitude of about 50 dB are dominated. As the peak amplitude values increase, the number of signals decreases.

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