Evaluation of the failure progress in the static bending of GFRP laminates reinforced with a classic plain-woven fabric and a 3D fabric, by means of the vibrations analysis

The aim of the work is to evaluate the effectiveness of analysis of a failure progress of the glass fiber reinforced polymer laminate (classic and 3D), during static bending, with the use of high frequency vibration analysis (the order of kHz). During the tests, the instantaneous velocity of the samples' vibrations was recorded. The 3D laminate showed a more favorable course of failure (mostly fiber fracture) than the classic laminate (mostly delamination), but only in the direction transverse to the translaminar interweave strands. In the direction parallel to the interweave, it was also characterized mainly by delamination. It was stated that the vibration measurements significantly broaden and supplement the characteristics of bending, by way of revealing the local degradation changes in the examined material, especially before the initiation of the main stage of failure. The work also describes the frequency bands in which the symptoms of the occurring failures of particular laminate components were observed and where the values of the basic point parameters were estimated, which points to the occurrence of structure failure. The obtained results confirm the effectiveness of the vibration analysis as a tool for the evaluation of the course of composite material failure under static loads. POLYM. COMPOS., 38:1070–1085, 2017.