Vibration study of CFRP laminated plates with acoustic black holes under hygrothermal environment

This work presents a comprehensive investigation of the vibration behaviour of CFRP laminated plates containing circular Acoustic Black Hole (ABH) indentations under hygrothermal environments. A semi-analytical Gaussian Expansion Method (GEM) combined with Classical Laminate Plate Theory (CLPT) is employed to efficiently characterize the flexural response of laminated ABH plates, accounting for laminate anisotropy, temperature- and moisture-dependent stiffness degradation, and attached damping layers. The formulation incorporates a matrix-replacing strategy that enables accurate modelling of multiple ABHs with significantly reduced computational effort compared to full numerical methods. The study establishes the novelty of extending GEM-CLPT to hygrothermally affected laminated composites with ABH tapers, deriving an effective bending stiffness and cut-on frequency expression tailored to composite ABH plates. Validation against finite element simulations shows excellent agreement, with modal frequency errors typically below 0.2%. Parametric analyses reveal that increasing the number of ABHs enhances vibration localization and transmission loss (TL), with cross-ply and orthotropic laminates exhibiting up to 40–50 dB broadband attenuation. Temperature rise substantially weakens the ABH trapping behaviour, while moisture effects remain comparatively minor. The results provide practical guidelines for designing ABH-integrated CFRP plates for vibroacoustic performance in demanding operational environments.