Numerical and Theoretical Investigation of the Acoustoelastic Effect of Tensile and Shear Stress on the Propagation of Ultrasonic Lamb Waves in Plate

Abstract

Initial stress affects the propagation of ultrasonic guided waves and therefore is relevant for the structural health monitoring field. Typically, only normal pre-stress is considered in the wave propagation. In this work, the effect of another relevant loading case, namely, shear stress, on the propagation of ultrasonic guided waves is investigated utilizing the finite element and semi-analytical finite element modeling while a stochastic metamodeling analysis is also presented. An aluminum plate is considered where the initial stress is set either as longitudinal tensile or shear stress along the propagating direction. Both methods show good agreement, revealing that for the fundamental Lamb wave modes and evaluated stress levels, the phase speed difference due to shear stress is less than due to tensile stress; however, speed changes quadratically with the shear stress level, unlike tensile stress which shows a linear behavior. Additionally, autoregressive and functional stochastic models are employed in view of a metamodeling approach to represent and assess stress effects on guided waves.