Ultrasonic detection of cracks in uniaxial glass fibre rods

Abstract

A non-destructive examination procedure based on a guided wave inspection approach is used for the acoustic examination of glass fibre reinforced composite rods. This paper contains an investigation into the characteristics of guided wave propagation in the rods. The authors attempt to model the excitation and transmission of waves along undamaged as well as damaged rods in order to predict the received signals, and we compare the model results with experimental data. Specially developed waveguide finite elements are used to determine the wave propagation characteristics of the rod. This yields an understanding of its wave dispersion characteristics and allows for the selection of appropriate excitation modes. Conventional transient finite element modelling is performed in order to determine what effects cracks have on the passage of the induced waves, and therefore also on the eventual output signals. Additionally, the determination of crack reflection coefficients is discussed