Theoretical Analysis for Propagation Behavior of Ultrasonic Guided Waves in CFRP Stiffened Panels

Abstract

Stiffened composite panels have been widely used in various structures, enhancing the significance of maintaining the structural integrity of joints between the patches and the baseplates. Ultrasonic guided waves are expected to be used for inspection of these panels because of their ability to monitor structural health and inspect inaccessible areas. However, guided waves propagating in anisotropic materials exhibit complex behavior compared to isotropic materials, and geometric and material discontinuities make the signals more complicated. To utilize guided waves to monitor the condition of the joints, we attempt to investigate the guided wave propagation behavior in composite stiffened panels. Mode conversion occurring between the general and stiffened areas is predicted by deriving phase velocity dispersion curves to compare the phase velocities of these areas, and by computing correlation coefficients of displacement profiles to estimate the matching of wave structures. Thereafter, for predicted modes, the amplitude ratio between signals before and after transmitting the stiffened area is estimated by the power flow in each area computed with the acoustic Poynting’s vector.