Investigation of displacement amplitude effect on failure mechanisms in open-hole laminated composites under low-cycle fatigue loading using acoustic emission

High ratio of strength to weight in carbon/epoxy composites causes to their applications in several structures, especially aerospace structures. In addition, to enhance the reliability in such structures, investigating damages in composites is essential. One way to detect defects in composites is to utilize the acoustic emission approach. Thus, the objective of the present research is to find failure mechanisms in open-hole laminate composite specimens with 〖[0_3/〖90〗_2/0_2]〗_s layup under cyclic loadings at different displacement amplitudes, using the acoustic emission. First, the standard specimen was examined and elastic waves due to failures in the specimen were detected by acoustic emission wide-band sensors. Two methods have been utilized to detect the failure percent, including Pocket wavelet transform and Fuzzy clustering approaches. Results from these methods were compared to micro-structure images by the scanning electron microscopy. Obtained results in this research indicated the appropriate efficiency of the acoustic emission approach to detect the type of failures and their percent in laminate composites.