This proposal is built around a well-established set of laboratory-based techniques, which use Thermoelastic Stress Analysis (TSA) for characterising strain fields associated with structural features. It is proposed to extend their applicability to aircraft structure tests and to enhance their productivity through the use of automation for data acquisition and processing in an industrial environment. Thermoelastic stress analysis is well-established as a laboratory-based technique and its use for structural analysis , fracture mechanics and damage mechanics has been explored extensively. Most of the work so far has been performed using relatively small test coupons with simple structural features. In the proposed work the aim is to prove the feasibility of applying thermoelastic stress analysis in a structural test environment for detecting stress hotspots. The structural test tools developed will enable fast acquisition of data-rich stress fields in large aerospace components during structural tests at relatively low cost and the post-processing capabilities will allow meaningful comparison of experimental results with those from computational models and service life evaluations. The scientific and technical objectives are designed to lead to innovative methodologies that will enable more detailed stress information to be acquired during aircraft structure tests. These methodologies will be faster, lower cost and provide higher confidence in computational models than is possible at the moment.

The aim of the project is to develop advanced integrated testing methods that have the capability to detect a crack or delamination in a metallic or composite structure and have the potential to be deployed as part of an on-board structural health monitoring system for passenger aircraft. The proposal incorporates a new philosophy for monitoring damage in which the disturbance to the strain field in the structure caused by the damage is used to identify significant damage and to track its propagation. Recently, this approach has been demonstrated to be at least as effective in composite structures as traditional non-destructive evaluation techniques and, in CS2 project INSTRUCTIVE using infrared technology, it has been shown to be capable of identifying smaller cracks in metallic structures than any other available technique. In this project, it is proposed to amalgamate these innovations with more established techniques, such as strain gauges and acoustic emission, and to demonstrate an integrated testing method. The objectives are designed to mature technologies from TRL 4 to 6 that are likely to have a disruptive impact on the structural health monitoring of next generation large passenger aircraft The objectives are: i) to develop a robust and innovative concept for integrating a diverse set of sensors and data acquisition systems for detecting and monitoring damage in an aircraft assembly; ii) to produce an integrated system of sensors and data acquisition systems deployed on a test bench representing an aircraft assembly, and; iii) to conduct prototype demonstration and evaluation tests of the integrated system and test bench using independent systems. The primary outcome will be the demonstration, on a test bench consisting of an aircraft assembly, of an integrated measurement system for ‘on-line’ detecting and monitoring damage based on a diverse range of sensor systems.