A two-dimensional pseudospectral model for time reversal and nonlinear elastic wave spectroscopy.

Area of Science:

• Materials Science
• Nonlinear Acoustics
• Computational Mechanics

Background:

• Characterizing metallic materials with defects requires advanced methods to analyze their dynamic nonlinear elastic response.
• Dislocation networks and microcracks significantly alter material behavior, necessitating sensitive detection techniques.
• Existing methods may lack the precision for detailed microdamage imaging.

Purpose of the Study:

• To introduce and validate a novel method, Nonlinear Elastic Wave Spectroscopy with Time Reversal (NEWS-TR), for microdamage imaging in metallic materials.
• To numerically demonstrate the feasibility of NEWS-TR for precise defect localization.
• To investigate the influence of filtering techniques on the retrofocusing quality for nonlinear components.

Main Methods:

• Development of a two-dimensional pseudospectral time domain algorithm.
• Integration of the Nonlinear Elastic Wave Spectroscopy (NEWS) method with a Time Reversal (TR) process.
• Introduction of hysteretic nonlinear behavior using the Preisach-Mayergoyz model and Kelvin notation for the elastic coefficient tensor.

Main Results:

• The NEWS-TR method successfully demonstrated its potential for microdamage imaging in simulations.
• Retrofocusing of nonlinear components onto defect locations was achieved.
• Pulse inversion filtering proved more effective than classical harmonic filtering for harmonic generation, particularly for filtering fundamental components.

Conclusions:

• The NEWS-TR methodology is a feasible and valuable technique for microdamage imaging in metallic materials.
• The quality of retrofocusing is dependent on parameter choices, including filtering methods and nonlinear effects.
• This approach offers a promising avenue for non-destructive evaluation and material characterization.