Session: Nonlinear Ultrasonic Techniques for NDE

Paper Number: 168642

168642 - Does Sideband Peak Count – Index (Spc-I) Technique Capture the Nonlinear Response of Materials? 

Abstract: 

The sideband peak count–index (SPC-I) technique has been widely used to assess material nonlinearity. However, its ability to capture true nonlinear responses has not convinced some critics yet. This is because SPC-I variations can be generated by both linear scattering effects and nonlinear response. Changes in linear scattering modes can influence SPC-I values, making it difficult to determine whether the observed variations stem from material nonlinearity or purely from linear scattering. However, confirming the ability of SPC-I technique to sense intrinsic material nonlinearity is of vital interest to the structural health monitoring (SHM) community. This work investigates whether SPC-I can truly capture nonlinear material behavior. Numerical simulations are conducted using an isotropic nonlinear elastic material modeled as a “Murnaghan material” characterized by second- and third-order elastic constants (SOECs and TOECs). A nonlinear plate is excited at different amplitudes. The amplification factor (AF) for these excitations is defined as the ratio of the input ultrasonic excitation to its baseline value (the first input excitation value). Finite element simulations using Comsol multiphysics demonstrate that for different AF values while SPC-I remains constant for linear materials, it exhibits variations for nonlinear materials. Moreover, the changes in SPC-I are found to be dependent on how the material stiffness varies with stress. When stiffness decreases with increasing stress, SPC-I increases with AF values. This trend is also observed for elasto-plastic materials and further validated through Abaqus/CAE simulations.  If the material stiffness increases with stress the sideband peak intensity can increase or decrease with increasing AF depending on what frequency range is considered. The modeling and experimental results presented here confirm that SPC-I can capture the nonlinear responses of materials, reinforcing its significance in material characterization and damage detection, thus offering valuable insights for the SHM community.

Presenting Author: Tribikram Kundu University of Arizona

Presenting Author Biography: Professor of Engineering at the University of Arizona. Fellow of ASME, ASCE, ASNT, SPIE and ASA; Distinguished Fellow of IIAV and Lifetime member of Alexander von Humboldt Foundation of America

Authors:

Guangdong Zhang University of Arizona
Meng Wang Sapienza University
Umar Amjad Qatar University
Hamad Alnuaimi Qatar University
Tribikram Kundu University of Arizona