Fully-flexible Thin-film Ultrasonic Array for use in Industrial NDE Applications

Ultrasonic inspection is the go-to tool for many industrial NDE applications. Ultrasonic arrays have been employed in NDE since the 1980's. However, with the rise of complex, computer-generated geometrical structures, the demand for arrays with the ability to conform to these structures is more pressing than ever before. The work here reports on the development of a truly flexible ultrasound array that allows previously uninspectable objects to be ultrasonically inspected.A novel, thin-film, piezoelectric material is deposited onto a flexible substrate using reactive sputtering of a metal-oxide-based alloy [1]. Additive manufacturing processes are then employed which allow for the mass manufacture of flexible arrays with consistent acoustic output and build quality, capable of operating in the region of 1-100 MHz. The arrays are subsequently demonstrated and tested on a variety of geometries such as moderate-diameter pipes and more complex test pieces. Moreover, these arrays are also demonstrated as permanently installed sensors, providing a solution to improved continuous monitoring with more information available to the industry.Data presented here includes sensitivity analysis and performance of a 64 element 15 MHz ultrasonic array. This was carried out using industry-standard NDE equipment, and common laboratory ultrasound apparatus. Preliminary testing has given strong indication that fully-flexible ultrasound arrays may be the future of industrial condition monitoring.Results demonstrated an array with effective performance following repeated flexion, indicating that they can withstand repeated conforming to test surfaces. The arrays tested achieved an average center frequency of 34 MHz, and average bandwidth at -6dB of 76%.