Second-harmonic generation in sound beams reflected from, and transmitted through, immersed elastic solids

Area of Science:

• Acoustics
• Solid Mechanics
• Nonlinear Acoustics

Background:

• Second-harmonic generation (SHG) is a nonlinear acoustic phenomenon.
• Understanding SHG in elastic solids is crucial for material characterization and nondestructive testing.
• Previous models often simplified solid properties or interface interactions.

Purpose of the Study:

• To experimentally investigate second-harmonic generation in sound beams reflected and transmitted through thick isotropic elastic solids.
• To validate a theoretical model for SHG in this context.
• To accurately describe nonspecular phenomena near critical angles.

Main Methods:

• Experimental measurements of diffraction patterns.
• Comparison with a theoretical model based on integral solutions for harmonic generation.
• Application of classical linear theory for reflection and transmission at fluid-solid interfaces.

Main Results:

• Experimental measurements of diffraction patterns were compared with theoretical predictions.
• The theoretical model accurately described the observed phenomena, including nonspecular effects.
• The study confirmed the validity of the model for thick solids where internal reflections are negligible.

Conclusions:

• The developed theoretical model provides an accurate description of second-harmonic generation in thick elastic solids.
• Nonspecular phenomena near critical angles are well-captured by the model.
• This work advances the understanding of nonlinear acoustic wave propagation in solids.