The Journal of the Acoustical Society of America 144, 1572 (2018);
Abstract:
Nonlinear ultrasonic guided waves have been investigated widely in closed waveguides such as
plates, pipes, etc. However, the description of nonlinear ultrasonic guided waves remains challenging
for open waveguides, as energy may leak into the surrounding medium. In this work, the properties
of nonlinear ultrasonic guided waves in open waveguides are investigated. Mathematical
framework is first established based on real reciprocity relation and modal expansion with perfectly
matched layers. Numerical models are then implemented, including nonlinear semi-analytical finite
element (SAFE) method to predict the properties of nonlinear ultrasonic guided waves, and time
domain finite element models to simulate the nonlinear guided wave propagation and cross validate
the predictions from the nonlinear SAFE method. Two examples, an aluminum plate attached to an
elastomer and an aluminum plate with water loaded on one side, are studied to demonstrate the proposed
methods and reveal some interesting phenomena that only exist in open waveguides. It is
interesting to find out that the amplitude of the attenuated second harmonic wave in immersed
waveguides can keep constant with propagation distance, only if the primary wave is non-leaky,
which may bring potential non-destructive test applications for underwater inspections. Such a feature
is validated by well-designed experiments in one-sidedly immersed plates.
Copyright (2018) Acoustical Society of America. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the Acoustical Society of America.