Array transducers contain many elements (array), arranged in different configurations, in a single housing. Pulsing these elements in sequences (phasing) results in different ultrasound beams.

The benefit of this technology is the ability to steer and focus ultrasound beams to optimize inspection by using a range of angles and focus points. Because part of the scanning is done by the beam motion, inspections, where access is limited or for complex geometries, are greatly simplified. For weld inspection, the ability to cover the complete volume of the weld as well as the heat affected zone using many angles at a time greatly increases the probability of detection. Furthermore, focusing at multiple depths improves defect sizing for volumetric inspections. Focusing and steering is done by pulsing the elements at different times. The waves originating from these sources interact with each other by either adding or subtracting their energy which produces the various angles and focus depths in the part to inspect. The same principle is applied at reception. Different delays are applied to the signals received by the elements to produce a single beam at an angle or focus point.

Usually, elements are pulsed in groups of 4 to 32. This is what is referred to as the aperture. Increasing the aperture improves sensitivity, reduces beam spreading and thus makes for a sharper focus.

There is a variety of phased array probes commercially available. Linear array probes are the most common. There are also circular, annular, square arrays and special design for particular applications.

For the purpose of this presentation we will show beam steering and focusing of a linear array probe.

Linear scanning 0° Sectorial scanning-30° to +30°Focusing

At reception, the signals amplified, filtered, digitized, processed, and displayed. The results can be viewed in A-scans, B-scans, and C-scans. Depending on the type of instrument used, other view option can be used.

Axionz follows the ASNT - Level II Phased Array syllabus.


1.0 Introduction

1.1   General introduction to ultrasonic testing
1.2   A brief history of phased array testing
1.3   Types of equipment currently available
1.4   What is a phased array system?
1.5   What do they do?
1.6   Advantages of phased array as compared with conventional UT

2.0   Transducers

2.1   Conventional transducer construction
2.2   Conventional beam characteristics
2.3   Wave front dynamic properties in conventional probes
2.4   Composite monolithic transducers
2.5   Single element transducer chara terization
2.6   Inside a phased array transducer
2.7   Phased array transducer characteristics
2.8   Phased array wedges
2.9   Phased array pulsing and its effects
2.10   Focal law sequencing
2.11   Beam shaping
2.12   Beam steering
2.13   Grating lobes and side lobes
2.14   Focusing with phased array probes
2.15   Phased array probe selection summary

3.I   Imaging Basics

3.1   Introduction
3.2   A-Scan data
3.3   Single Value B-Scan
3.4   C-Scan mapping
3.5   Phased array C-Scan
3.6   Cross sectional B-Scan
3.7   Phased array Linear scans
3.8   Phased array Sectorial scans (S-scans)
3.9   Combined image formats
3.10   Overview of beam effects on sectorial scans

4.0 Phased Array Instrumentation

4.1   Overview
4.2   Instrument block diagram
4.3   Important specifications
4.3.1   Conventional instruments
4.3.2   Phased array instruments
4.3.3   Calibration and normalization methods
4.3.4   Combined phased array and conventional UT instruments

5.0   Anatomy of Phased Array Display

5.1   Anatomy of Phased Array Display
5.2   Focal Law Setup
5.3   Straight Beam Linear scans
5.4   Angled Linear Scans
5.5   Focal Law Sequence
5.6   Defect Positioning
5.7   Interpreting Sector Sector

6.0   Typical Applications

6.1   List of current applications notes

Eligiblity Required

Minimum requirement for Candidates:

  • Well experienced in Ultrasonic Testing & its application.

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