A new approach to determine tensile stress states from the parameters of longitudinal waves

In this paper, an experiment is proposed to select longitudinal ultrasonic waves as the physical agent in the detection of tensile stress states. The delay time in the back-wall echo travel presents a relation with the strain usually considered in tensile tests. From an algebraic manipulation procedure, this time interval is the fundamental quantity in the proposed method. The theoretical development initiates from the sound velocity in the unstressed state and employs a perturbative method to quantify the changes in the time-of-flight due to both the dimension modifications and the acoustoelastic effect. In addition to Armco iron and rail steel, this study applies its mathematical model to metal-matrix composites of aluminium and SiC particles at different temperatures. The scheme requires one transducer to perform the corresponding measurements to evaluate if a metallic material is under tensile stress. (C) 2020 Elsevier Inc. All rights reserved.