Experimental Evaluation on Acoustic Emission Wave Propagation of Laminated Composites with Cutouts Using Auto Sensor Testing

This study investigates Acoustic Emission (AE) wave propagation in large cantilever composite panels using experimental and numerical analysis. Five distinct case studies, considering two distinct scenarios—panels with and without cutouts—were investigated under various boundary conditions and excitations. The boundary conditions and support deviate from prevailing AE studies on flat panels supported by simply supported structures to focus on cantilever support that resembles aeroplane wings. A comparative study on the effectiveness of the Hanning Window Function, Sine, and square wave functions in characterizing wave propagation within laminated composite structures was investigated. Variations of the Hanning window function at frequencies of 100 kHz, 400 kHz, and 55 kHz are examined to assess their impact on stress wave time-of-arrival. Through experimental endeavours and three-dimensional (3D) numerical models, meticulous analyses on stress wave propagation time-of-arrival, frequencies, and excitation waveform were performed. Experiments were conducted using the Auto Sensor Testing (AST) feature for its superior repeatability and data acquisition over conventional methods such as pencil-break and impulse hammer tests. Results from Case I (without cutout) and Case III (with cutout) show that the wave propagation time from trigger sensor 1 to sensor 3 was 78.5 µs for the panel without a cutout and 125.5 µs for the panel with a cutout. This significant time discrepancy underscores the impact of boundary conditions and excitation waveforms on wave propagation in panels with and without cutouts. Comparative analysis affirms specific excitation waveform and frequency suitability, aligning numerical results with experimental observations, thereby substantiating the reliability and accuracy of the proposed numerical methodology.