Guided wave propagation in anisotropic materials and the practical implications for operating point selection

Abstract

Ultrasonic guided wave propagation in anisotropic attenuative materials like CFRP is much more complicated than in isotropic materials. Propagation phenomena need to be understood and quantified before reliable NDE/SHM inspections systems can be realized. The propagation characteristics: energy velocity, dispersion, energy focusing factor and attenuation are considered in this paper. Concepts of minimum resolvable distance and sensitivity maps are extended to anisotropic attenuative materials in order to provide the means for comparison of different guided wave modes in composite materials. It is shown that minimum resolvable distance is a more complex phenomena in anistropic materials and care must be taken when considering the directions of propagation ultimately detection capability. Similarly when designing an inspection the distribution of energy in a structure must be considered to determine the feasibility of a given inspection.