An alternative Rayleigh wave excitation method using an ultrasonic phased array.

Area of Science:

• Materials Science
• Mechanical Engineering
• Non-Destructive Testing (NDT)

Background:

• Ultrasonic Rayleigh waves are crucial for in-service NDT inspection across industries.
• The conventional wedge technique for Rayleigh wave excitation faces challenges like transmission loss and limited waveguide flexibility.
• Surface crack detection and sizing using Rayleigh waves is an area of active research.

Purpose of the Study:

• To introduce an alternative method for Rayleigh wave excitation using conventional ultrasonic phased array transducers.
• To address the limitations of the wedge technique, including transmission losses and angle dependency.
• To demonstrate a flexible and efficient approach for generating Rayleigh waves in various materials.

Main Methods:

• Utilized a conventional ultrasonic phased array transducer with controlled element excitation delays.
• Estimated excitation delays based on transducer pitch and Rayleigh wave velocity.
• Validated the method through experimental testing and Finite Element (FE) simulations.
• Quantified directivity and beam divergence of generated Rayleigh waves.

Main Results:

• Successfully demonstrated unidirectional and selective excitation of Rayleigh waves.
• Experimental results showed strong agreement with FE simulations.
• The proposed method proved effective across a range of materials using the same phased array transducer.
• Characterized generated waves to confirm their nature as Rayleigh waves.

Conclusions:

• The phased array transducer method offers a viable alternative to the wedge technique for Rayleigh wave excitation.
• This novel approach enhances flexibility and potentially reduces inspection costs in NDT.
• The method holds significant potential for developing advanced Rayleigh wave-based inspection techniques.