Evaluation of Multiple Reflections in the Characterization of Anisotropic Materials by Through Transmission Ultrasonic Technique

Ultrasonic through-transmission techniques have been widely used along decades for determining the elastic constants of anisotropic composite materials. This work presents a new methodology that takes into account not only the transmitted waves but also the multiple reflections inside the sample. The superposition of different reflected waves are theoretically and experimentally identified and excluded, which avoids the distortion caused by pulse superposition. Additionally, the results of the Christoffel tensor optimization are evaluated in the reflected waves, improving the results validation. Experimental results using unidirectional carbon-matrix composite samples used in the aeronautical industry are presented.