An ultrasonic method to measure stress without calibration: The angled shear wave method

Area of Science:

• Materials Science
• Structural Engineering
• Non-Destructive Testing

Background:

• Accurate stress measurement is vital for structural health monitoring and predicting remaining service life.
• Existing ultrasonic methods for in-plane stress analysis often require material constants or specimen-specific calibration, limiting real-world application.
• These limitations hinder robust in-situ stress evaluation in diverse environments.

Purpose of the Study:

• To present a novel ultrasonic method for direct, in-situ evaluation of in-plane stress.
• To develop a technique that bypasses the need for pre-determined material constants.
• To offer a robust and broadly applicable solution for structural stress assessment.

Main Methods:

• The method utilizes the measurement of the speeds of two angled shear waves.
• It is founded on a formula derived for incompressible solids, with approximate validity for compressible solids like metals.
• Finite element simulations were employed to validate the proposed formula and methodology.

Main Results:

• The ultrasonic method accurately determines in-plane stress directly and in situ.
• The technique does not require prior knowledge of material constants.
• Finite element simulations confirmed the method's high accuracy, with errors around 1%.

Conclusions:

• The developed ultrasonic method provides a simple and accurate approach for in-situ stress evaluation.
• This technique offers a significant advancement over existing methods by eliminating the need for material constants and calibration.
• The findings have broad implications for structural health monitoring and life prediction in various materials, including metals and biological tissues.