Grant: Discovery Grants Program - Individual

The main objective of this research program is to develop new strategies for non-contact characterization and inspection of complex structures using air-coupled ultrasound transducers. Generation and measurement of ultrasound waves in air using single element transducers is well mastered for range detection and Non-Destructive Testing (NDT). However, due to the complex alignment process, applications are still limited to non-contact inspection of simple configurations such as plates or shells. To overcome this limitation, multi-elements transducer strategies will be investigated in this research.In the past decade, multi-element Micro-ElectroMechanical Systems (MEMS) have been proposed for distributed or focalized generation and measurement of ultrasound waves. However, the reduction of transducer footprint was prioritized for portability, such that power requirements, frequency range, and transducer arrangements are currently not adapted for NDT or medical imaging of realistic structures. For this reason, in order to achieve acceptance of the air-coupled inspection method in this field, a major breakthrough has to be made on the following requirements: detection performance, conformation to complex geometries, and process automatization. To address these issues, an integrated approach for non-contact surface mapping and inner structure inspection has to be developed. This is why the proposed research program is organized along three distinct research thrusts: design sparse array of air-coupled transducers, propose automated methods for surrounding object detection, and develop advanced imaging algorithms for inner structure characterization. The novelty resides in the use of sparse transducer arrays in combination with advanced array processing methods in order to retrieve indications on the surrounding objects and their inner structure.Targeted applications include complex environment characterization for automated vehicles (drones, autonomous cars), passive acoustic detection for predictive maintenance of structures (bearing or contact monitoring, leak detection, fatigue testing), but more specifically automated and non-contact inspection of civil or aerospace structures (composite assemblies, concrete slabs).The proposed research program will address for the first time the challenges associated with the use of air-coupled inspection methods for complex structures: surface irregularities, inhomogeneous medium, local curvature. The demonstration of such method will open new avenues for automated inspection in both industrial (aerospace, civil engineering) or even biomedical (non-contact imaging for automated interventions) domains, that might decrease diagnostics time in both NDT and medical procedures, while limiting the human intervention that may impair the prognostics.