Full Wavefield Analysis for Damage Assessment in Composite Materials

Abstract

In this paper damage assessment based on guided elastic wave propagation phenomenon is presented. Guided waves are generated by piezoelectric transducer and registered by scanning laser doppler vibrometer (SLDV). Signal processing is based on the analysis of full wavefield measurements gathered from dense mesh of measurement points spanned over area of investigated samples. Full wavefield measurement approach allows creation of animations presenting the guided wave propagation in the structure. Moreover such approach is suitable for analysis of interaction of guided waves with discontinuities located in structure. In the research attention is paid especially on analysis of phenomenon of S0/A0' guided wave mode conversion due to interaction with investigated discontinuities-teflon inserts and impact damage. The presented work is related to glass fibre reinforced polymer (GFRP) samples. In the research, auxiliary non-destructive testing (NDT) method is also utilized. The aim of this method is to indicate the depth of discontinuity, and to prove that delamination was created in the case of impact damage. Auxiliary method is based on terahertz spectroscopy (THz) where the analysis of propagation of electromagnetic waves in the terahertz band is conducted. THz spectroscopy method can be utilized for damage assessment in the dielectric materials like GFRP.