Simulation of Layer Thickness Measurement in Thin Multi-Layered Material by Variable-Focus Laser Ultrasonic Testing.

Area of Science:

• Materials Science
• Non-Destructive Testing (NDT)
• Ultrasonics

Background:

• Thin multi-layered materials are critical in high-technology industries.
• Accurate layer thickness measurement is essential for quality and safety.
• Existing non-destructive testing (NDT) methods face challenges in precision for thin layers.

Purpose of the Study:

• To propose a novel non-destructive method for measuring individual layer thickness in multi-layered materials.
• To utilize ring-shaped laser-generated focused ultrasonic bulk waves for enhanced measurement.
• To improve the efficiency and accuracy of layer thickness determination.

Main Methods:

• Generation of shear waves with variable focus using a ring-shaped laser with a variable radius.
• Analysis of signal characteristics at the ring center based on laser radius variation.
• Finite element simulations to model ultrasonic wave propagation and reflection in multi-layered structures.

Main Results:

• The proposed method directly measures layer thickness by analyzing reflected shear wave convergence.
• Successful measurement of layer thickness in simulated bi-layer and 3-layer structures.
• Demonstrated increase in pulse-echo signal-to-noise ratio (SNR) and prevention of aliasing signals.

Conclusions:

• The novel ring-shaped laser-generated focused ultrasonic method is feasible for thin multi-layered materials.
• The technique offers higher efficiency and accuracy compared to conventional NDT methods.
• This approach provides a reliable solution for quality assessment in advanced material applications.