Numerical analysis of hoop stress and failure mechanisms in GFRP rings verified by acoustic-emission experiments

Filament-wound glass fiber-reinforced polymer (GFRP) cylinders are widely used in various industries due to their high strength-to-weight ratio and corrosion resistance. Understanding their failure mechanisms under hoop stress is critical for ensuring their structural integrity and reliability. This study investigates hoop stress and failure mechanisms in ±65 ∘ filament-wound glass/epoxy composite rings using numerical modeling, acoustic emission analysis, and machine learning. Split disk testing and non-destructive acoustic emission testing were performed. Failure mechanisms were identified via acoustic event registration and clustering with the SOM algorithm, and waveform analysis was conducted using continuous and discrete wavelet transforms. A finite element model in ABAQUS with the Hashin damage criterion (via VUMAT subroutine) was developed to analyze hoop stress and failure modes. The differences between experimental and finite element results for maximum force and displacement were 8.7% and 6.6%, respectively. The SOM algorithm and wavelet transforms identified three failure modes: matrix cracking and crack propagation (46.36% relative energy), delamination and fiber-matrix debonding (37.44%), and fiber fracture (16.20%). Finite element analysis revealed fiber tension and matrix tension modes as predominant failure modes. Energy analysis identified three temporal regions: initiation of microcracks, saturation of matrix cracking and initiation of delamination, and fiber breakage.