Full Matrix Capture

Full matrix capture (FMC) is a data acquisition strategy that allows for the capture of every possible transmit-receive combination for a given ultrasonic phased array transducer.

Acquired data is processed in real-time using an optimised version of the total focusing method (TFM) algorithm, which generates fully focused images from the FMC data. This phased array ultrasonic testing (PAUT) technique increases the reliability of ultrasonic inspection, leading to reduced costs and improved safety for industry.

How Full Matrix Capture Works

FMC is a method of collecting phased array data that doesn’t require knowledge of the piece that is being inspected. This non-destructive technique involves the activation of each element (or shot) one-by-one, with each of the array elements also used as receivers to create a signal data matrix.

Once the data matrix has been collected, focusing is applied via post-processing algorithms to create a result for points in the inspection volume. Processing methods found within industry include Total Focusing Method (TFM), Sectorial Total Focusing (STF), and Inverse Wavefield Extrapolation (IWEX).

Full matrix capture can be used to image sub-surface flaws in components, creating fully focused imagery. This is achieved by gathering the full time-domain of each possible transmit/receive combination and then discretising this into a finite grid. Each cell in this data matrix grid acts as a focal point, representing a pixel in the final image. This high resolution, fully focused image is able to show even small flaws in the sub-surface of a component in real time.

TWI Crystal^TM Software

TWI’s Crystal^TM Software is an advanced ultrasonic inspection package that allows for the inspection of structures through automated Full-Matrix Capture as well as Virtual Source Aperture (VSA) and Plane Wave Imaging (PWI).

The system provides an intuitive interface for high defect detection and sizing accuracy capabilities, allowing for real time automated inspection of assets through planar and complex geometry structures. These capabilities, coupled with a real time scanning and date/image display, mean that the system can be integrated into both production and in-service environments for industries including aerospace, defence, nuclear, oil and gas, and rail. You can find out more about Crystal^TM Software by visiting the dedicated website.

Benefits of Full Matrix Capture

Fully focused images
High sensitivity to small flaws
High resolution
Signal-to-noise levels equivalent to phased array
Real-time inspection
Ease of inspection setup as no complicated focal laws involved
Ease of interpretation

Challenges of Full Matrix Capture

While the benefits of Full Matrix Capture are evident, there are still some drawbacks with the technique, notably that it produces large data files, slow scanning speeds and reduced signal-to-noise ratios (SNR) since the data is collected after pulsing just one element at a time.

However, these challenges can be overcome by collecting half-matrix data or not saving all of the A-Scan data. In addition, the use of different processing and phasing techniques, such as plane wave imaging, can improve the SNR issues.

FMC techniques are still subject to the same focalisation issues faced by regular phased array ultrasonic inspection (PAUT), meaning that compromise may be required to find the most effective solution.

TWI has expertise in FMC and other types of non-destructive testing, including training. You can find out more about our services and TWI CrystalTM by contacting us by email: contactus@twi.co.uk.

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