Elastic constants identification for laminated composites using laser doppler vibrometry and an inversion method based on legendre orthogonal polynomial expansion
摘要
Nondestructive characterization of elastic constants for laminated composites is critical for certifying manufactured composites before their use in various engineering applications. This paper presents an ultrasonic guided wave-based inversion approach, which leverages (i) noncontact laser Doppler vibrometry, (ii) frequency-wavenumber analysis, as well as (iii) an inversion algorithm with a unique objective function based on Legendre orthogonal polynomial expansion (LOPE) and genetic algorithm (GA) optimization, for determining the elastic constants of laminated composites. To implement this approach, laser vibrometry is used to acquire time–space wavefields of guided waves. The wavefields are then transformed into frequency-wavenumber spectra via multi-dimensional Fourier transform, unveiling the frequency-wavenumber relations in different directions, which are subsequently processed by our LOPE-based inversion algorithm. Particularly, this algorithm allows for robustly determining multiple elastic constants without requiring guided wave mode identification. Additionally, it is a generalized approach applicable to laminated composites with various anisotropic lamina properties and layups.