Abstract

An experimental procedure has been developed to characterize the interlaminar resistance of composite materials, specifically prepregs of vinylester-epoxy nature, based on the determination of their critical energy by the realization of consecutive low energy impacts on test specimens of the studied material.The impact sequence was performed by means of a certified impactor, based on a pendulum system, and the system used to measure the integrity of the material after each impact consisted in the NDT optical pulsed thermographic technique. In the present study, a series of 8 specimens made of unidirectional glass fiber with different arrangements and specific treatments, both on the reinforcement and the resin matrix itself, were used to carry out its characterization, as it is an asymmetric fabric based on a surface of continuous fibers and the other surface with glass veil finish. The NDT technique used has enabled, on the one hand, to quickly and efficiently identify the breakage of the materials and to determine the critical energy, and on the other hand, it has made possible to precisely measure the area of the delaminated zones and to determine their localization in depth through the graphic representation by means of projection in RGB channels.The results obtained in the characterization using the proposed procedure have been validated with fracture energy tests in mode I and II, obtaining satisfactory levels of correlation between both procedures.