Active Thermography in Through-Life Engineering

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With the increased use of high-value components in aerospace industries, there is huge emphasis on reliability as their failure in service could lead to catastrophic failure of the system. Thus, there continues to be increasing dependency of such high-value components to undergo critical maintenance routines in order to reduce the probability of failure. The prediction of Remaining Useful Life (RUL) is a critical factor in estimating the service cost. It has direct impact upon product and service pricing. With increasing maintenance costs, manufacturers have adopted a range of techniques such as non-destructive testing (NDT) to help assess the serviceability of these high-value components, where a component is inspected for quality without causing damage to the part. This allows for inspection of entire batches, instead of sample subsets. In service-focussed business models such as the aerospace sector, high-value components are required to perform for an optimum life cycle, balanced between maximising operation hours and a confidence in its safety. NDT has become a key process in determining the current state of degradation during the component’s use, allowing estimation of remaining life and determination of repairs required. Detection of defects and anomalies is still a major challenge in the development of NDT practices in advanced manufacturing processes even more so with the introduction of new materials for higher reliability and performance. This research looks at expanding the NDT practices in maintenance by identifying the emerging challenges and suggesting areas of research for a robust development of NDT techniques and improved component degradation analysis. Active thermographic NDT is a recent technique that has become more widely included in NDT processes over recent years. However, due to its shallow depth and lower resolution limitations, it has not been exploited to its full potential in maintenance routines. Current challenges involve the further development of thermography as a quantitative technique as opposed to its traditionally qualitative implementations. This chapter focusses on the detection of damages caused due to component degradation using the pulsed active thermography technique. It also presents a novel approach on carrying out maintenance using an automated inspection system together with damage characterization of near and sub-surface damages on high-value components.