Material Lifeing Using Nonlinear Ultrasound

This project is concerned with the development of ultrasonic techniques for the detection of fatigue and creep damage in materials. This development will allow the detection of damage at earlier stages in power plants and aero engines, resulting in the ability to operate these systems safely for much greater periods. The noncollinear interaction of ultrasound with material nonlinearity will be developed and employed due to its great potential for practical applications. The development and comparison of nonlinear inspection techniques, through modelling and experiment, will provide academic and industrial users with a clear, unambiguous description of the relative performance levels and usefulness of nonlinear ultrasonic inspection techniques, helping future users make the best decisions as to which approach to apply. Finally the testing of this approach on real world samples will confirm its practical applicability. The result will be an understanding of how nonlinear ultrasonic techniques can be used to detect previously undetectable damage in specimens and predict the remaining life in components.

The beneficiaries of the proposed research fall into two main categories, industrial and local, both of which are crucial and must be considered. With the growing problem of ageing infrastructure in the power sector and the indus- trial need for damage detection in structures at an ever earlier stage, nonlinear ultrasonic techniques could have an enormous impact by allowing structures to operate longer and closer to their ultimate strength. This in turn could lead towards the ultimate goal of condition based maintenance. The development of the promising noncollinear technique and performance comparison of the different nonlinear approaches will give the industrial users the confidence to apply these approaches to practical situations, with the potential for large cost savings. In the event that the nonlinear techniques are less capable than ex- isting linear approaches, the proposal will clearly be beneficial for end-users in establishing this. The local impact is twofold, relating to both Dr Croxford and the employed researcher. As a first grant the proposal will help to ensure Dr Croxford establishes good links with industrialists and leave him well placed to play an active role in the development and deployment of techniques for monitoring material life in the future. Together with his work on guided wave SHM this will leave Dr Croxford well placed to develop his expertise in material lifeing and structural monitoring. The employed researcher will benefit through production of high quality publications and career development in a new potentially significant area. Perhaps more importantly, they will develop a set of skills that are particularly relevant to the aerospace and power sectors. This will have a great impact on their employability at the end of the proposal and in the long term will help to ensure excellent future links between academia and industry in key sectors.