Elliptical Method for Damage Identification in Carbon Fibre Reinforced Polymer Laminates

Oftentimes, researchers in the area of vibration-based Structural Health Monitoring (SHM) and Damage Detection focused their attention on the global properties of structures, which are the modal frequencies and modal damping factors. However, the effects on the local properties for SHM, that is modal constants, has not been so extremely explored. In this paper, the Elliptical Plane modal identification method is proposed to be used as a Damage identification method itself. It is observed that, when the receptance is plotted in the Elliptical plane, the area of the ellipse formed close to the resonant frequencies (which depends on the modal constants) can be used to detect damage, namely in composite Carbon Fibre Reinforced Polymer (CFRP) rectangular plates. Although a mathematical correlation has not been established yet, results show that the method is sensitive to the presence of damage in the test plates, as the area of the ellipse changes with damage.