Guided ultrasonic wave-based investigation on the transient response in an axisymmetric viscoelastic cylindrical waveguide

Abstract

The analysis of ultrasonic wave propagation in an axisymmetric viscoelastic cylindrical waveguide under time-dependent preload is presented. It requires investigation of the transient response for understanding the dynamics of a multi-wire structure for non-destructive evaluation and health monitoring applications. The purpose of this research is to establish a platform for calculating the time-transient response of waveguides for propagating acoustic emission (AE) signals using a semi-analytical finite element (SAFE) method. The time-transient response analysis is carried out in the frequency domain, which combines the Fourier transform and Cauchy residue theorem. The fundamental idea is to use the modal superposition method to calculate the frequency response at each point and then utilize the inverse Fourier transform to convert the response to the time domain. For the numerical investigation, an axisymmetric SAFE method is utilized to simulate the AE signal for propagating in an infinitely long, high-strength steel wire with a diameter of 5 mm. The time-dependent loads used in the numerical investigation for analyzing time-transient responses are narrowband and broadband excitations. A nonlinear model for transient response analysis is developed to consider the contact state and friction effects of the surrounding steel wires in the multi-wire environment. A nonlinear device consisting of contact springs and friction-type dampers is considered to account for the contact state and friction effects of the surrounding steel wires. The investigations are carried out with a single set and two sets of nonlinear devices under various stiffness values and preload conditions to understand the response characteristics. The estimated value of the contact spring stiffness is based on calculating the Hertz semi-width between the steel wires when the seven-wire steel strands are under tension. From observation, the standard nonlinear features input high-frequency fluctuation components into the original ideal linear system and cause extended high-frequency fluctuation at the tail of the waveform. The proposed nonlinear model for analyzing the preload condition in the axisymmetric viscoelastic waveguide showed a possible way for guided wave propagation-based health monitoring applications for prestressed cables. � 2021 Elsevier B.V.