Diffraction correction in high-precision pulse-echo and multiple-reflection ultrasonic measurement systems for fluids

Area of Science:

• Ultrasonic Measurement Systems
• Acoustic Metrology
• Non-Destructive Testing

Background:

• High-precision ultrasonic measurement systems require accurate diffraction correction models.
• Existing models based on baffled-piston theory may not fully capture complex diffraction effects.
• Prior work established a finite element diffraction correction (FEDC) model for one-way systems.

Purpose of the Study:

• To generalize the finite element diffraction correction (FEDC) model for n-way ultrasonic measurement systems (n=1, 2, 3,...).
• To compare the generalized FEDC model with existing piston-type diffraction correction models.
• To evaluate the necessity of accurate diffraction descriptions in high-precision ultrasonic applications.

Main Methods:

• Generalization of the finite element diffraction correction (FEDC) model for n-way systems with coaxially aligned piezoelectric transducers in a fluid medium.
• Comparison with baffled-piston models using specular reflection and 'new source' reflection approximations.
• Numerical simulations for a system with two identical cylindrical piezoelectric disks in a fluid.

Main Results:

• The generalized FEDC model provides a more comprehensive description of diffraction effects compared to piston-type models.
• Piston-type models show notable deviations from the FEDC model in both near- and far-field predictions.
• Deviations between piston-type models themselves were also observed, highlighting their limitations.

Conclusions:

• Accurate diffraction correction, as provided by the FEDC model, is essential for high-precision ultrasonic measurement systems.
• The choice of diffraction model can significantly impact measurement accuracy, depending on system parameters.
• The generalized FEDC model offers a more robust approach for various ultrasonic measurement configurations.