Towards CyberSHM: autonomous acousto-ultrasonic health monitoring of operational composite structures

Continuous monitoring of in-service safety-critical structures for real-time assessment of their operational health is receiving significant attention and is a highly topical area of research. This is can be attributed, among others, to the following two factors.
i) The rapid evolution of next-generation complex composite structures and their ubiquitous use as lightweight structures in several industries ranging from aerospace to offshore/onshore energy infrastructure, automotive and nuclear industry.
ii) The significant advancement of automation within a data-rich environment and the immense appetite of industries to leverage its benefits for transforming their traditional, often interventionist, practices.

Significant research investment into next-generation complex composite structures (such as the ongoing EPSRC grant EP/T011653/1) and their rapid uptake in industrial usage has brought to the fore concerns and challenges around monitoring of these structures. Investigations into the susceptibility of these structures to subtle, barely visible damages (like hidden debonding, fibre/matrix-cracking) reveal that the latter can significantly jeopardize the structural integrity and can lead to catastrophic failures. The recent multiple catastrophic accidents in the passenger flights involving aeroplanes manufactured by the world's erstwhile largest planemaker has rightly enhanced the scrutiny on the safety, serviceability and suitability of such structures for public use. This is coupled with objectives for employing greener and sustainable structures (to meet the global emissions target as pledged in the Paris Climate Agreement 2016) and reducing operational costs associated with their inspection and maintenance without compromising on safety.

Concurrently, with a paradigmatic shift towards industrial internet of things within Industry4.0 with ubiquitous, pervasive computing coupled with advanced sensing and communication technologies, it has become a necessity to develop structural health monitoring (SHM) solutions of safety-critical engineering structures which are abreast of, can reap the benefits of and are able to fit seamlessly into this intelligent, data-rich environment of automation.

The proposal is aimed at fundamental scientific investigation into and the technological implementation of monitoring of lightweight composite structures to bridge the gap between the conceived futuristic vision of SHM and the existing interventionist practices of evaluating structural health. The objective of this project is to address the challenge of real-time acousto-ultrasonic monitoring (akin to "listening for damages" and/or changes in structural response) and online damage identification of operational structures using a multi-pronged approach with the key components being -
a) physics-driven underlying model or digital equivalent of structural ultrasonic waveguides behaviour under various operational/ambient conditions,
b) the extraction, synchronization and utilization of structural acoustic fingerprints of damage events (such as tool drop, delamination, cracks) as collected by the onboard sensory network for data-driven training and classification of damage events and
c) a real-time damage identification toolbox (identifying the location, type and severity) which is both data-driven (in-situ sensor data) and model-informed (physics-based understanding of structural waveguides) to give quantified metrics of incipient damage along with their estimated confidence.

The project takes the novel approach of assimilating physics-based characterization structural acoustic characteristics with data from hybrid passive-active acousto-ultrasonic monitoring and interrogation of the monitored structures for a cyberphysical monitoring or CyberSHM of in-service structures.