Introduction

New materials for aerospace have enabled the construction of structures that are very light, but at the same time subject to problems of propagation of high-frequency mechanical waves (ultrasound). The wavelength of such waves excited by special piezoelectric interdigitated shape transducers (IDTs) can be on the order of mm, thus capable of interacting with material defects or alterations.
The patent covers a non-fragile, low-cost and reliable IDT capable of inspecting such structures because it can be implemented with fabrication on piezpolymer films that are metallized and mechanically attached to the structure without altering its profile (smart skin).

Technical features

The patented transducers are intended for monitoring structures in hostile and prolonged scenarios, as they are small in shape and size and made on piezopolymer film. The proposed technology allows the selection of guided propagation modes when the transducer is installed on a foil: the presence of alterations in the structure is detected by changes in the characteristics of the guided waves.
The advantages of the patented technology are: (a) electrode shaping is able to optimize coverage of the area of interest by reducing the number of transducers; (b) the absence of complex wiring, with reduced weight and cost; (c) piezopolymer film technology allows design by laser ablation, thus rapid prototyping, production and adaptability; (d) the manufacturing process replaces photolithographic techniques to remove metallization, resulting in low environmental impact; (d) unlike piezoceramic transducers, which are very fragile, the patented transducers are inert and stretchable enough to be able to withstand mechanical deformation and vibration of structures without breaking.
The TRL of the technology is 4.

Possible Applications

• Monitoring of aerospace structures;
• Monitoring of pipelines;
• Monitoring of tanks for the transport and use of liquid natural gas and hydrogen;
• Monitoring of hulls and chassis;
• Non-destructive testing of objects for carbon sports use (bicycles, tennis rackets, golf clubs).

Advantages

• Optimization of transducer density by electrode shaping resulting in reduced wiring complexity, weight and cost;
• Realization of electrode shaping by laser ablation resulting in rapid prototyping, production and adaptability to requirements;
• Environmentally friendly transducer manufacturing process;
• Non-fragile, inert, flexible piezopolymer materials also suitable for making multifunctional sensors.