ACOUSTIC EMISSION FOR DAMAGE MONITORING OF COMPOSITES MATERIAL

Activation of different damage mechanisms during each stage of loading is one of the distinctive characteristics of composite materials which are not unavoidable. In this paper, Acoustic Emission (AE) technique as a non-destructive testing method is developed to detect damage mechanisms in each stage of buckling loading of glass/polyester composite materials. Acoustic Emission, NDT method that is based on radiation induced defect activation is based on the structure during loading. Such damage detection of composite parts is very important. Four types of specimen at different layups, [0,90]6s, [45/-45]6s, [0]6s and [woven]6s leading to different level of damage evolution, were studied. During buckling loading, data from mechanical testing and acoustic emission is obtained and its features are analyzed in time-domain. Among the extracted features, count, energy and amplitude variations were more distinctive to show the evolution of damage mechanisms. In this way, the fractured surface of each specimen is prepared and analyzed by SEM to find the type of damages that are existed during loading. SEM observations show that the damage mechanisms including matrix cracking, fiber breakage, debonding and fiber pull-out. This observations are in relation with the results are obtained from AE. The results show that there is a good relation between what AE features variations have proposed and what SEM observations during testing. Also, the efficiency of AE as a useful tool for damage evolution and monitoring is concluded

کلیدواژه ها:

Glass/Polyester ، Non-Destructive Testing ، Acoustic Emission ، Damage Mechanisms ، SEM