Laser Vibrometry and Dispersion Analysis-Enabled Mechanical Property Characterization for Additively Manufactured...

Large-format additive manufacturing of thermoset composites enables rapid fabrication of large structures, but nondestructive characterization of their print-path-dependent mechanical behavior remains difficult. Existing qualification routes rely mainly on destructive coupon testing or defect-oriented nondestructive evaluation and therefore provide limited capability for targeted mapping of direction-dependent mechanical variability. This study presents a piezoelectric transducer-laser Doppler vibrometry framework for direction-conditioned dispersion inversion of full-field guided wave measurements in additively manufactured thermoset composites. The method decomposes the frequency-wavenumber spectrum by propagation angle and independently fits the extracted dispersion data in each propagation direction to obtain scan-region-specific effective shear-wave velocity, an effective Poisson's-ratio parameter, and effective-modulus responses as functions of propagation direction. Benchmark testing on an isotropic aluminum plate validates that the workflow recovers isotropic guided wave behavior without introducing artificial angular bias. Applied to a chopped-carbon-fiber thermoset composite, the framework reveals print-path-dependent anisotropic wave propagation through elliptical wavefields and frequency-wavenumber spectra. The resulting effective stiffness estimates reproduce the direction-dependent stiffness variation and approximate magnitude observed in conventional tensile measurements, supporting the mechanical relevance of the guided wave-derived response. By converting full-field guided wave measurements into scan-region-specific, direction-resolved effective-stiffness estimates, this work provides a practical nondestructive route to support quality control, process validation, and structural evaluation of aerospace composite tooling manufactured by large-format thermoset additive manufacturing.