Ultrasonic and microscopic investigation of impact damage in GFRP composites

Some aspects of ultrasonic evaluation of impact damage in glass fiber-reinf orced plastic (GFRP) composites are discussed in this paper. First and fore most, results of a microscopic investigation are reported which illustrate the structural properties of GFRP composites and show that, contrary to the assumption used in the current literature, no delamination occurred in the samples examined in this work when the energy of impact was lower than 9 J . Second, a simple ultrasonic approach to assess the maximum spatial extent of the damaged volume is presented. The evaluation of the damage spatial e xtent obtained by this method is shown to correlate well with that recovere d by a direct microscopic investigation. Finally, in view of the findings o btained by the microstructural analysis, a brief discussion is presented wh ich reviews the properties a nondestructive method should possess in order to provide reliable quantitative assessment of impact damage in GFRP compos ites.