Delamination Detection in a Multilayer Carbon Fiber Reinforced Plate Based on Acoustic Methods: Numerical and Experimental Study

In this paper, we present the results related to the development of a technique for low-frequency acoustic non-destructive testing of layered composite structures. The main goal was to detect and pinpoint potential bundles in such structures. To do this, we used as an object of research a manufactured carbon fiber panel consisting of eight layers, with the addition of inclusions between the fourth and fifth layers. By performing a finite element analysis of the effects of an omnidirectional piezoelectric transducer mounted in the center of the panel, we found that the amplitudes of the out-of-plane velocities increase significantly near the lamination regions. Our technique includes the use of a laser vibrometer and a simple method of velocity analysis that allows us to detect and accurately locate lenticular delaminations within the geometry under study. It was found that the results of the simulation were sufficiently like to the experiment. In addition, we also considered a model case, where the defect is located between the first and second layers of the panel. It is noted that the behavior of the velocity field in this case differs from the previous variant, but the average amplitude of the out-of-plane velocity undergoes a slight decrease relative to the case of the defect occurring in the center of the thickness.