Abstract
In this paper, the guided ultrasonic wave propagation characteristics in the axisymmetric pre-stressed viscoelastic waveguide for acoustic emission (AE) monitoring, using the semi-analytical finite element (SAFE) method, is studied broadly. For the numerical investigation, a single high-strength steel wire is considered. A comprehensive and in-depth study on the AE signal’s propagation characteristics is carried out based on the SAFE method. Both undamped and damped waveguides are considered for attaining SAFE solutions and presented in a detailed manner. The SAFE method for an axisymmetric cross-section in cylindrical coordinates analyzes the two main influencing factors of steel wire in a practical scenario: Material damping and initial tension. For the effect of initial stress, the calculation shows that the initial tensile stress can increase and decrease the energy velocity and attenuation factor of most modal waves above the cut-off frequency, and the effect is linear. Some longitudinal wave modes in the high-frequency region show their potential for AE monitoring as these modes have a low attenuation factor and small external surface vibration. By considering various states of initial stress in a damped waveguide, the effect of pre-stress on the dispersion characteristics is understood in a better manner. A non-destructive testing (NDT) mechanism for pre-stressed steel wire using AE monitoring is proposed for the health monitoring of structures.
Highlights
The guided ultrasonic wave propagation technique has significantly attracted worldwide attention, as it provides researchers, engineers, and infrastructure owners a more reliable way to monitor structural conditions for preventing failure
By considering various states of initial stress in a damped waveguide, the effect of pre-stress on the dispersion characteristics is understood in a better manner
For modeling ultrasonic guided wave propagation, many finite element methods have been used for attaining an exact solution based on the superposition of bulk waves, which includes matrix methods [8]
Summary
The guided ultrasonic wave propagation technique has significantly attracted worldwide attention, as it provides researchers, engineers, and infrastructure owners a more reliable way to monitor structural conditions for preventing failure. The basic idea is to discretize the waveguide medium’s cross-section into a finite element (FE) form while preserving wave propagation’s theoretical formula in the axial direction [9,10,11,12] In this way, the eigenvalue system for a modal solution is established, and the original frequency equation is converted into eigenvalues to solve the problem. To study the guided ultrasonic wave characteristics, including the effect of initial stress and structural damping, the axisymmetric SAFE method is utilized. This paper discusses the SAFE method of the axisymmetric cross-section for an undamped and damped condition and comprehensively considers the AE signal’s propagation characteristics in a single steel wire. This study can help select an appropriate mode with low attenuation characteristics that may be useful for monitoring AE and NDT events
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