Non-Destructive Evaluation of Impact-Damaged Sandwich Composites: Influence of Fiber Type

This study deals with the evaluation of impact-damaged sandwich composites using different fiber types (carbon, glass, and Kevlar), where the outer layers, or “skins”, were made from the same type of fiber, while the inner layer, or “core”, consisted of a different fiber type, with the aim of improving the damage resistance and tolerance of composite materials. To achieve this goal, the following research question was formulated: can the type of core fiber used in sandwich composites primarily determine their structural response under impact? To obtain a consolidated answer, various configurations manufactured were subjected to low-velocity impact tests to induce damage. The next step involved evaluating the extent and distribution of damage across various samples using ultrasonic C-scan techniques, along with assessing the impact bending stiffness (IBS) property, a widely recognized method for measuring the structural response of composites. It was observed that the different composite configurations presented distinct absorbed energy and, consequently, different damages, which was confirmed by the IBS and the C-scan methods. The glass–carbon–glass (GCG) sandwich composite demonstrated superior performance in mitigating damage compared to the other sandwich designs. The core material was verified as the main factor influencing the response of the sandwich composite.