Simultaneous use of pulse-echo and through-transmission methods in determining a combined reflection coefficient

Most ultrasonic applications in non-destructive testing (US-NDT) by contact use pulse-echo or direct transmission reception. Because of the nature of each method, part of the data is not retrievable. Thus, jeopardizing the analysis and synthesis of information. However, by applying these methods together, the joint approach can provide additional evidence from NDT. This study proposes a novel procedure that combines the most common US-NDT that includes rationale and theory. The goal is to improve the reflection coefficient assessment that is defined as the combined reflection coefficient (CRC). The determination of this parameter can improve the estimates of the attenuation of the medium when only one sample is available or when immersion techniques cannot be applied. The proposed arrangement uses one transducer as a transmitter and two transducers located on opposite sides of the working piece as the receivers. The measurements were performed simultaneously with the two receiving transducers. The general equations relate the signal amplitudes and identify the energy losses in each reflection within the material and its interface. The graphs show the amplitude loss. Furthermore, numerical simulations using the k-Wave software indicate an exponential relationship between the CRC and amplitude losses and the traditional ultrasonic methods and their combination. The theory was verified by numerical simulations using the k-Wave software and experiments with two aluminium samples at two ultrasonic frequencies of 2.25 MHz and 5.0 MHz. The usefulness of the new method for the determination of the CRC, including improvements in the estimates of acoustic attenuation in low-loss pieces, was proven.(c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

This study proposes a novel approach in ultrasonic non-destructive testing by combining multiple common ultrasound methods and improving attenuation estimation through measuring the reflection coefficient. The method utilizes a transmitter, two receivers, and analyzes the relationship between signal amplitude and energy losses.