Numerical Simulation of Guided Wave Inspection

The modelling of ultrasound uses computational numerical simulations to model the propagation of ultrasound waves in complex geometries. By being able to accurately predict ultrasound behaviour through complex media it is possible to improve the design of ultrasound transducers, signal processing and image quality, reducing scattering and allowing for improved imaging across the cross sectional imaging plane in real time.

Finite element analysis (FEA) and numerical modelling are used to simulate the behaviour and propagation of guided waves in structures such as pipes and rails, and the interaction of these waves with defects. FEA is based upon the underlying finite element method (FEM) mathematical model that divides complex structures into simpler elements through computational methods.

These simulated waves can model ultrasound scattering for detecting defects such as cracks, corrosion, and the inspection of industry assets such as pipes and rails. Advances in the modelling processes are moving towards the use of large-scale 3D simulations capable of predicting wave propagation in heterogeneous media.

Ultrasound models can be used to optimise ultrasound transducer designs ahead of committing to the cost of physical manufacture or prototyping.

Core Research Programme (CRP) and Joint Industry Projects (JIP)

Core Research

Each year the TWI Core Research Programme (CRP) addresses challenges on behalf of our Industrial Members as well as developing specific technologies and processes. Each of the projects under the CRP is focussed on engineering, materials or manufacturing technologies.

Joint Industry Projects

TWI also conducts Joint Industry Projects (JIPs) that bring together groups of Industrial Members to share the cost of research activities in areas of mutual industrial interest, gaining exclusive access to the outcomes. These projects cover a broad range of topics.

Modelling of Ultrasound at TWI

TWI has expertise in the use of numerical modelling to identify suitable guided wave modes for use in guided wave inspection; simulating the interaction of guided waves with defects in structures and interpreting the signals received during inspection of engineering components.

Through the use of parallel processing TWI is able to provide the computational power required to produce models in the timeframes required to deliver highly accurate models suitable for industrial use. The accuracy of the results required for ultrasound modelling requires small element sizes and short time-steps.

Our knowledge and capabilities in the modelling of ultrasound allow us to conduct bespoke research on behalf of our Industrial Members as well as for the wider benefit of industry. This includes developing the technology for new applications such as rails, storage tanks, bridge suspension cables and bridge pre-stressing tendons.

Advantages of a combined modelling and experimental approach include:

Development of new techniques for measuring the dimensions of flaws

Validated simulation of different components, material types and coatings

Optimised probe array design and location for improved defect detection

Integration of client technical drawings for rapid simulation of complex structures

Rapid production of inspection prototypes - meeting complex industrial requirements

Evaluation of difficult situations such as branches, joints, and holes

Benefits and Applications

Numerical modelling has been used to extend the capability of guided wave testing to include assessment of defect size (e.g. the extent of corrosion damage to a pipeline) and identification of the circumferential location of a defect in a pipe. This information reduces operating costs for users by allowing decisions on maintenance to be made based on remote inspection, with no need for more costly local inspection.

TWI Modelling of Ultrasound Projects

The use of FEA to extend the capability of guided wave inspection is described in a number of Industrial Member Reports. TWI Industrial Members can access the full reports and non-members can see summary extracts of some example projects, here:

762/2003 ('Finite element analysis of long-range ultrasonic waves in metallic structures of arbitrary cross section')

886/2007 ('Improvements in guided wave focusing technology for detection of defects in pipelines')

911/2008 ('Innovative techniques for sizing locally thinned areas in straight pipes and for inspection beyond pipe bends using guided waves')

1025/2012 ('Modelling and inspection of pipes containing bends using long-range guided waves').

For more information, on the modelling of ultrasound and how we can help you meet your challenges, please email contactus@twi.co.uk.