Layered material characterization using ultrasonic transmission. An inverse estimation methodology.

Area of Science:

• Materials Science
• Acoustics
• Non-destructive Testing

Background:

• Accurate material characterization is crucial for predicting material behavior and ensuring structural integrity.
• Identifying acoustic and mechanical properties of layered materials is challenging due to complex wave interactions.
• Inverse Problems (IPs) offer a robust framework for inferring material properties from measured data.

Purpose of the Study:

• To develop and validate an inverse methodology for characterizing layered materials.
• To identify acoustical and mechanical properties of individual layers within a material.
• To investigate the frequency dependence of wave attenuation in homogeneous materials.

Main Methods:

• Utilizing Inverse Problems (IPs) theory, specifically parameter estimation.
• Solving the IP by minimizing a cost functional based on waveform differences.
• Employing ultrasonic transmission tests to obtain measured waveforms.
• Developing an equivalent model for waveform calculation.

Main Results:

• Accurate estimation of acoustic impedance, transit time, and attenuation for layers in materials up to three layers thick.
• Successful identification of material properties such as sound speed, density, and elastic constants.
• Discovery of a power law frequency dependence for wave attenuation in homogeneous materials.

Conclusions:

• The proposed inverse methodology is effective for characterizing layered materials using ultrasonic data.
• The method provides a reliable way to determine key acoustical and mechanical properties of material layers.
• The findings contribute to a deeper understanding of wave propagation and attenuation in materials.