Session: Virtual Presentations in Acoustics, Vibration, and Phononics

Paper Number: 96718

96718 - Biaxial Stress Inversion in Plate-Like Structures Based on Acoustoelastic Guided Waves 

Guided waves play an important role in both nondestructive evaluation (NDE) and structural health monitoring (SHM) because of their long propagation distance and high sensitivity. The acoustoelastic effects provide a good potential to measure prestress non-destructively. When propagating in a compressed elastic medium, the elastic wave velocity changes with the applied stress, which is the basis of ultrasonic techniques with acoustoelastic guided waves. Even though a variety of methods have been proposed in previous studies to predict the behavior of acoustoelastic waves, the study of acoustoelastic effects in stress detection methods is limited. The current acoustoelastic stress inversion methods are mainly to extract stress information by analyzing the change of acoustic wave velocity or spectrum information. There is no general method to detect axial stress that can be applied to sections of any shape. In theoretical studies, the acoustoelastic effect can be described by finite nonlinear elasticity theory and weakly nonlinear elasticity theory. The former allows for large deformations and is mostly used to describe the acoustoelastic effect in soft solids, such as gels and tissues. The present study is set within the framework of weakly nonlinear elasticity theory, which focuses on elastic wave propagation in prestressed stiff solids. Here we consider the small pre-deformation to study the propagation of guided waves under prestress, setting within the framework of weakly nonlinear elasticity theory.

In this work, a SAFE method is first proposed to calculate guided-wave dispersion curves in isotropic prestressed materials with arbitrarily shaped cross-sections. For the stress inversion method, the theoretical conditions under which the present derivation is valid are discussed in light of previous work. Based on the sinusoidal relationship between the propagation angle and phase velocity change, using information known to be subjected to uniaxial stress, multi-angle or multi-frequency methods were developed to invert biaxial stress, respectively. Different from the previous work, this method provides a new idea: transform the time domain information of multiple points into the dispersion information of the object through matrix pencil; the nonlinear effect of uniform biaxial stress on the material is decoupled into two acoustoelastic coefficients. A new method for inverting stress from the change in the phase velocity of the guided wave without considering the shape of the cross-section was developed. The above inversion method has been verified by the results of SAFE and finite element method (FEM). The verification of the inversion of the stress value by different methods all obtained the MAE error of about 1%. In the finite element method, it is also a new attempt to use the chirp signal as the excitation signal to sweep the surface waves.

Presenting Author: Chunyu Zhao Tianjin University

Presenting Author Biography: Chunyu Zhao earned her Bachelor’s degree in measurement and control technology and instruments at School of Automation Engineering, Nanjing University of Aeronautics and Astronautics. She is currently continuing her research as a MS student at State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University. Her interests include stress inversion using acoustoelastic guided waves. She is also interested in the acoustic field and inversion of stresses in complex structures.

Authors:

Chunyu Zhao Tianjin University
Xin Chen Southwest Research Institute
Jian Li Tianjin University
Yang Liu Tianjin University