Experimental Study on Dispersion Analysis of Guided Waves Based on Pencil Lead Break Actuation Scanning

Accurate acquisition of dispersion characteristics is a critical prerequisite for structural health monitoring (SHM) of composite material structures using the ultrasonic guided wave. However, conventional methods face significant challenges in resolving dispersion behavior during practical inspections of composite laminates and filament-wound cylindrical structures. To address these limitations, this paper proposes a dispersion analysis method based on pencil lead breaks actuation scanning (PLBAS). Firstly, a dedicated pencil lead break actuation (PLBA) device was developed, and a trigger timing alignment strategy was established to overcome calibration mismatches between PLB events and data acquisition systems. This innovation enables efficient experimental spatial-temporal wavefield data collection for dispersion analysis in composite structures. Secondly, dispersion curves of aluminum plates, composite laminates, carbon fiber reinforced aluminum alloy laminates, and hydrogen storage cylinders were reconstructed through two-dimensional fast Fourier transform (2D-FFT). Finally, the method’s validity was confirmed by comparing experimental group velocity with theoretical ones, with results showing average errors below 5% in group velocities. This approach provides a robust and efficient solution for dispersion characterization in metal and composite plate-like and filament-wound cylindrical structures, offering potential for broader applications in SHM of complex composite systems.