Characterization of delaminations in composite laminates by laser ultrasonics

Abstract

Abstract The influence of delaminations in the anisotropic carbon fiber reinforced plastics (CFRP) on laser- generated ultrasound is investigated. A 3D-finite element method is used to simulate the propagation of ultrasonic waves in CFRP with delaminations. The asymmetric properties and distortions as well as the wave reflection and attenuation at delamination interfaces are clearly shown. Measurements on CFRP specimens with circular delaminations above 2 mm in diameter are imaged by C-scans and correlated to the modeling results. The effects of ultrasound frequency, defect size and depth location are discussed. The results show that it is possible to decrease the influence of anisotropy in CFRP composites by choosing appropriate ultrasonic frequencies and controlling the laser parameters.