J. Russell

ULTRASONIC PHASED ARRAY INSPECTION OF FLAWS ON WELD FUSION FACES USING FULL MATRIX CAPTURE

Work is being conducted to develop phased array inspection of stainless steel welded pipes. Ideally this uses waves reflected and mode converted at the inner surface of the pipe, but most commercial phased array controllers do not currently provide for this. Our solution was to use Full Matrix Capture (FMC) and process the data ourselves. This paper explains the FMC principle, describes the signal processing algorithms along with introducing the Almost Total Focusing Method (ATFM) and illustrates how the processed data was presented. The inspections were also modeled using the CEA CIVA software and compared to experimental results.

INSPECTION OF COMPONENTS WITH IRREGULAR SURFACES USING A CONFORMABLE ULTRASONIC PHASED ARRAY

A conformable phased array device has been developed for the inspection of components with irregular surface geometry. This low‐cost device uses a standard linear phased array coupled to the pipe‐work surface via a water‐filled, low‐loss membrane. The membrane coupled device allows rapid scanning of components with irregular surfaces without the need for multiple angled probes and time consuming mechanical scanning. Comparison testing between the conformable array and conventional rigid wedge technology demonstrates that internal noise within the membrane coupled device housing degrades inspection performance. Further development of the device has been completed, significantly decreasing this noise and improving device performance.

THROUGH‐WELD ULTRASONIC PHASED ARRAY INSPECTION USING FULL MATRIX CAPTURE

Rolls‐Royce and Imperial College are developing phased array inspections for welded stainless steel piping with an undressed weld cap. An inspection that proves particularly challenging requires ultrasonic waves to propagate across the irregular weld‐cap profile, and through the structurally complex weld material. Simulations of ultrasonic wave propagation through the weld region were obtained using the CIVA software to predict the effect on inspection performance. Simulated and experimental data was collected as Full Matrix Capture (FMC) which was then processed using our own software with results then displayed in a Beta version of CIVA. An investigation was conducted to confirm the principle of updating delay laws for variations in material properties.

VARIABLE SPLIT APERTURE PROCESSING OF FULL MATRIX CAPTURE PHASED ARRAY DATA

Work is being conducted to develop phased array inspection of stainless steel welded pipes. Defects can occur anywhere along the weld fusion face. Optimum inspection performance across the entire weld face can be facilitated by collecting data as Full Matrix Capture (FMC) and applying a processing technique that allows focusing to be ideal for every pixel within the Bscan image. Further improvements to the Bscan image can be made by having a split aperture that varies as a function of focal depth. This paper introduces the FMC principle and describes the variable split aperture signal processing. The inspections were also modeled using the CEA CIVA software which was compared to experimental results.

DEVELOPMENT OF A TWIN CRYSTAL MEMBRANE COUPLED CONFORMABLE PHASED ARRAY FOR THE INSPECTION OF AUSTENITIC WELDS

The inspection of welded austenitic stainless steel components can be challenging. Austenitic welds contain an anisotropic, inhomogeneous grain structure which causes attenuation, scattering and beam bending. The inspection of components where the weld cap has not been removed is even more difficult due to the irregularity of the surface geometry. A twin crystal membrane coupled device has now been produced containing two linear phased arrays positioned adjacent to one another within the same housing. The arrays are angled relative to one another so that the transducer provides a pseudo‐focusing effect at a depth corresponding to the beam crossing point. This type of design is used to improve the signal to noise ratio of the defect response in comparison to simple linear phased array transducer designs and to remove an internal noise signal found in linear phased array devices. Experimental results obtained from the through weld inspection of an austenitic stainless steel component with an undressed weld ...

DEVELOPMENT OF A MEMBRANE COUPLED CONFORMABLE PHASED ARRAY INSPECTION CAPABILITY

A membrane coupled conformable phased array device is under development to improve the inspection of components with irregular surface geometry. This device uses a conventional linear phased array, which is coupled to the surface of the component under test via a water path encapsulated by a low loss rubber membrane. The membrane coupled device has recently been updated to provide improved beam forming, reduced internal noise and an integrated irrigation system. An enhanced inspection system is under development that allows the rapid acquisition and processing of scanned full matrix capture (FMC) inspection data. Results from a challenging inspection of an austenitic component are provided demonstrating how the membrane coupled phased array device can be used to detect defects where other techniques cannot be used.

FINITE ELEMENT MODELING OF ELASTIC WAVE PROPAGATION AND DEFECT INTERACTION IN LARGE, COMPLEX COMPONENTS

Rolls‐Royce Marine and Imperial College, London are working together to develop a conformable phased array membrane probe for the inspection of components with complex surface geometry. This device will allow inspection of welded components without the need to remove the weld cap. To assess the performance of the membrane device it must be benchmarked against conventional inspection techniques. As an aid to inspection qualification (IQ) a range of advanced modelling techniques are also under investigation. This paper reports on the experimental results obtained form this benchmark testing and compares these results to simulated data.