1997 Volume 46 Issue 4 Pages 360-365
In this paper, the residual life and the creep damage for glass fiber reinforced plastics are studied experimentally. For this purpose, emphasis is placed upon introducing a new damage parameter defined by acoustic emission (AE) intensity in order to evaluate the micro-damage accumulation generated before macro-crack initiation in a composite. Short-term creep experiments were carried out on three types of specimens, consisting of glass fiber fabric reinforced epoxy laminated composites with different weaves, counts, densities and thickness. The single-edge notched specimens were subjected to a series of stepwise loadings with increasing peak loads, in edgewise four-point bending so that tensile stress arose at the front end of the notch. AE activity was monitored with measuring mechanical displacement during a test using various AE intensities, which were analyzed in detail. The new damage parameter showed a good correlation with a conventional damage parameter defined by non-elastic deformation caused during cyclic load holdings. The correlation depended on test conditions and materials but was presumed to stand up under tensile deformation.
