Qinetiq are seeking an academic partner and a PhD student for an Industrial Mathematics Internship.

Description of proposed work plan

In the course of development of a Structural Health Monitoring (SHM) system, employing ultrasonic guided waves, QinetiQ has employed a transfer-matrix model developed in Matlab to guide the design of ultrasonic transducers which are to be permanently mounted on the structure to be monitored. Whilst this model has provided some useful insight, its performance and validity is limited in several respects:

• The model is essentially one dimensional and assumes a purely ‘thickness extension’ or ‘plate’ mode of vibration that ignores the shape of the piezoelectric element. The model could be extended to include ‘bar-mode’ and ‘beam-mode’ vibration.

• The model assumes a monolithic, homogeneous, layer structure. It cannot, for example, accommodate interactions between adjacent elements in an inter-digital array.

• The model makes no allowance for velocity dispersion in the material layers. Dispersion allowance could be accommodated by inclusion of the shear wave velocity of the layer materials.

• Only limited model testing has been carried out using published literature.

The project will focus developing a more comprehensive model that overcomes the limitations listed above. The first two of these essentially concern a 2-dimensional extension of the model and a further extension could also include the effect of diffraction losses resulting from beam spread on the round-trip between piezoelectric element and a reflector in the substrate structure.

Validation of the model will also be an important component of the work; this can be done through reference to existing literature but it is not always the case that publications are consistent and there may be some need to carry out validation based upon in house tests and also extreme boundary conditions.

If time and resource permit, the model could be further extended to include scattering from defects at particular locations within the forward terminal layer that represents the structure being monitored.

The intern will be supervised by QinetiQ staff and will be expected to work closely on both model development and results. Output from the project would be­ a practical Matlab code that can be used to implement and update the model and a report describing the model, its operation and performance.

The areas of expertise and/or interests required by the candidates are in:

• Matlab programming
• Model evaluation
• Knowledge of multidimentional wave modelling would be advantageous

The candidate should also be a good communicator.

The intern will experience work in QinetiQ's Managed Services Division, specifically in the Non-destructive Evaluation (NDE) Group, working on conventional NDT and Structural Health Monitoring (SHM). The work is primarily connected with aerospace, but also covering applications in the Energy sector. There might be an opportunity of following the project work to a practical conclusion, when the sensors are fitted to QinetiQ's aircraft based at Boscombe Down.

Duration of the project:
6 months

Company location
Farnborough, Hampshire

Industrial supervisor
Roger Dalton

For more details and to apply for this internship, please email Vera Hazelwood at the Industrial Mathematics KTN.

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