Stress Corrosion Cracking in a Unidirectional E-Glass/Polyester Composite Subjected to Static and Cyclic Loading Conditions

This work evaluates the effects of static and cyclic loading conditions on the stress corrosion process in unidirectional glass/modified polyester composite in the presence of a nitric acid solution. The composites were investigated under static, cyclic, and static with overload conditions using a rectangular specimen with centrally positioned grooves. The stress corrosion process was monitored using acoustic emission (AE). It was found that the time-to-failure of the composite specimens were only slightly affected by loading conditions. However, the large scatter in the time-to-failure of the specimens did not allow for the proper evaluation of the effect of the cyclic loads on the stress corrosion fracture process. It seemed that the time-to-failure were more influenced by the specimen variations than by the type of loading. By using an AE digital set-up based on four transducers, not only can the fiber fracture by stress corrosion be very accurately monitored, but also the location of AE sources can be precisely determined.