OmniSX MX2 Training 4E Phased Array Beam Forming

OmniScan SX \ MX2 Training ProgramPhased Array Beam Forming Chris Magruder V4.1B2T9 OmniScan SX \ MX2 Training – Phased Array Wedges Overview Phased array wedges perform the same function as conventional UT wedges by coupling sound energy from the probe to the material at the desired refracted angle and wave type. Phased array wedges come in all shapes and sizes for various applications and are an essential part of the inspection. Phased array wedges are used to assist the probe in beam formation for shear wave and longitudinal wave inspections, just like conventional UT. 1D Wedges typically used in OmniScan SX\MX2 applications come in 3 varieties: 1. Shear wave angle beam. 2. Longitudinal wave angle beam. 3. Longitudinal wave straight beam. the software can be configured for the beam formation. Beam formation or focal law generation will determine the size. and material velocity. (A-scans). and material parameters before beam formation. shape. This is the purpose of the focal law calculator. Group setup wizard) The OmniScan XS\MX2 has a built-in group set up wizard that will step the user through the process of populating the probe. wedge. . Beam formation combines both angle steering and focusing. and angle of the beams.OmniScan SX \ MX2 Training – Beam Forming Overview After populating the focal law calculator with the parameters of the probe. wedge. Groups of A-scans or focal laws come in many configurations as a function of software. instrument capability. The OmniScan SX\MX2 refers to beam sets as groups and supports sector and linear scan groups in the calculator. . and probe capability. Other types of groups can be imported into the OmniScan SX\MX2 from an external focal law calculator.OmniScan SX \ MX2 Training – Beam Forming Overview cont. ability to reproduce conventional results. . one of the most important factors in determining the scan plan strategy is the ability to calibrate the group using traditional calibration blocks with SDHs and notches to improve inspection results and comply with construction codes. number of focal laws. range of angles. A-scan density. Additionally. and ability to minimize number of required groups for the inspection. 256 focal law limit.OmniScan SX \ MX2 Training – Group Formation The OmniScan SX\MX2 supports both linear and sector scan groups for 1D linear array probes and has an 8 group. Both sector scans and linear scans have unique advantages and limitations regarding weld coverage. Linear Group Sector Scan Definition Focal laws of different angles generated using the same elements. etc. (1 element.OmniScan MX2 Training – Group Formation . 2 element. A-scan density and coverage is defined by the range of angles (4570) and angle resolution. 47.) Linear Scan Definition Focal laws generated over a series of elements using the same angle.Sector vs. (45. A-scan density and coverage is defined by the element step resolution. 46. etc.) . Beam to beam resolution is the same regardless of sound path. Ease of calibration due to only one angle. Linear Scan Advantages Produces same result as conventional UT raster scan (X. (16. Compliance with existing codes referencing one angle inspections.Y). . 32) Fewer focal laws required for coverage of weld area.OmniScan SX \ MX2 Training – Group Formation .Sector vs. Improved flaw characterization from multiple angles. Linear Group Sector Scan Advantages Large coverage area from small footprint on component. Small element count required for instrument and probes. Requires instrument with large multiplexer. Multiple groups required for same coverage resulting in long set up. XX:128) . calibration time.OmniScan SX \ MX2 Training – Group Formation . Linear Scan Disadvantages Requires many focal laws. and big data file. Limitations in ability to calibration wide angle range for long sound paths. Linear Group Sector Scan Disadvantages Beam to beam resolution worse as sound path increases. (49 as pictured below) Poor coverage with one angle\one group.Sector vs. (XX:64. Limitations in ability to calibrate multiple TCG points for long sound paths. and build a TCG (If required) for every A-scan in the group. The calibration process.OmniScan SX \ MX2 Training – Beam Steering Limits Beam steering is limited by the probe element size and aperture. physics of UT (Snell’s law) and most importantly. sensitivity. includes maintaining the velocity at a known angle (Does not mode convert) and ability to correct the wedge delay. the wavelength. like conventional UT. the ability to calibrate each A-scan in the group to the satisfaction of the application or procedure. . . Small elements have greater beam spread and retain more energy at higher angles than that of larger elements. The maximum steering angle at -6dB can be defined from the beam spread equation below.OmniScan SX \ MX2 Training – Beam Steering Limits cont. As element size decreases so does energy and more elements must be pulsed together to maintain the same sensitivity. the wider the beam spread. The smaller the single element crystal. This is a similar to conventional UT. . size of calibration reflector. The OmniScan SX\MX2 calculator does not attempt to define the steering limits of any probe\wedge combination because there are too many variables in the inspection requirements including what is an acceptable A-scan signal to noise ratio for any one customer’s application.OmniScan SX \ MX2 Training – Beam Steering Limits cont. The limits of beam steering and focusing are dependent on many factors including size of aperture. material properties. etc. size and number of elements. Exit point of beam Index offset calculated by software and verified on IIW block Verified exit point is used to measure real angle in material (40 degrees) 40 degree A-scan 40 degree A-scan . The beam steering limits of a particular probe\wedge\aperture is reached when the highest and lowest angle of the group are not able to be verified within 1 degrees. This process is explained in detail a later section. Repeat…. The real exit point of the beam is verified with an IIW block and compared with the calculated value in the software. Once the exit point is validated the angle can be verified on the other side of the IIW block.exactly like UT.OmniScan SX \ MX2 Training – Verification of Beam Angle and Exit Point Beam steering angle (Refracted angle) is verified in phased array inspections exactly like conventional UT. The effective sensitivity is improved by a smaller beam diameter with more energy at the focus point. . The depth of focus is changed by varying the applied delays on the elements and is built into the focal law along with the angle steering. frequency.OmniScan SX \ MX2 Training – Beam Focusing Overview Sound beams can be focused like light rays with the energy focusing at a given point and then expanding beyond it. Increasing the size of the aperture or creating the same aperture using more elements of a smaller pitch increases the sharpness of the focused beam and improves results. and material velocity. The maximum depth or sound path that a beam can be focused is defined by the near field which is a function of element size. The near field is different in the active and passive axis of the array and can be calculated with the formula below.OmniScan SX \ MX2 Training – Beam Focusing – Near Field Beam focusing is only possible within the near field of the probe. . Most methods for calculating the near field should be considered close approximations due to simplifying the formula and not taking into account every probe parameter. OmniScan SX \ MX2 Training – Beam Focusing vs. Like conventional UT. etc. 1 2 3 4 1 2 3 4 1 2 3 4 . most of our code based phased array inspections such as ASME. TCG The near field calculation that defines the maximum beam focus limit is not the limit of the useful sound path for inspection purposes. A focal point is selected within the TCG range that can accommodate all points. API. are performed with an unfocused probe and a TCG or DAC to compensate for sensitivity (Amplitude) over time (Sound path). Use of a TCG for code based inspections reduces the benefits of focusing. (A-scan) Sound path focusing. Defined by an X. Defined from the bottom of the wedge in depth every beam.Y position in the material. Depth Sound Path Projection Focal Plane . There are five primary types of focusing associated with phased array inspection: 1. Defined by the sound path from the beam exit point. Any value that is beyond the near field or maximum focus distance of the probe\aperture. Unfocused. Projection focusing. 5. Depth focusing. 2.OmniScan SX \ MX2 Training – Inspection Focus Strategies Different focusing strategies can provide optimized results for different applications. 4. Defined by the surface distance from the wedge face. Focal plane focusing. 3. projection. . The OmniScan SX\MX2 focal law calculator only supports depth focusing. Sound path.OmniScan SX \ MX2 Training – Inspection Focus Strategies cont. and focal plane focusing can be imported into the OmniScan SX\MX2 from an external focal law calculator using the memory card. .OmniScan MX2 Training – Advanced Inspection Focus Strategies The majority of OmniScan SX\MX2 applications including weld inspection are well suited for depth focusing and do not benefit significantly from other focus strategies. An example of an application that would benefit from a specific focal plane other than depth is the dissimilar metal weld inspection in inconel using a low frequency longitudinal angle beam sector scan for maximum penetration and focus on the far side weld bevel. (Pictured in red in front of the probe) Note: Sound path display only available in MXU V3.OmniScan SX \ MX2 Training – Advanced Strategies – WSY \ ID Creeper Another example of an application that would benefit from an advanced focusing strategy is the phased array version of the conventional UT 30-70-70 (WSY) technique used for internal crack detection and sizing in the power generation industry. Projection focal plane Crack tip (70 degree) CE1 CE2 Crack base (55 degree) . A 55-70 longitudinal wave sector scan is focused in a vertical plane (Projection) at a fixed distance from the wedge face.2 in OmniScan MX2. In this application turbine components are inspected for porosity and laminar flaws before complex machining.5mm surface resolution on carbon steel components is possible from the Hydroform system with the aid of shallow depth focusing.OmniScan SX \ MX2 Training – Focus Strategies – Near surface The Hydroform inspection system uses a shallow depth focus to maximize near surface detection and resolution. 1. water column and high frequency probe. . small aperture. OmniScan MX2 Training – Verification of Beam Parameters In addition to standard IIW and similar calibration blocks. beam focusing. beam steering limits. etc can be verified similarly to the requirements of conventional UT with specialized reference standards. there are industrial standards such as ASTM E2491 that specify techniques and calibration block designs for verification of the phased array beam profile. Beam profile. . element activity. .and not the software. Start 1 2 3 . and beam forming) The OmniScan SX\MX2 like its predecessors is a UT flaw detector before it is anything else. and with the exception of software to manage the information unique to phased array it is very similar to a modern single channel conventional flaw detector with better imagery. and much greater power. more software features. The use of the OmniScan SX\MX2 setup and calibration wizards will make managing all of the parameters required for the phased array inspection fast and efficient permitting the focus to remain on the application……. wedge. (Probe.OmniScan MX2 Training – Phased Array Calculator Review At this point in the training all of the hardware parameters and basic software considerations required to prepare a phased array beam set or group in the OmniScan SX\MX2 have been described. material. . Material velocity. Wedge parameters. Beam formation. 3. 2. Answer: All of the above. Probe parameters. 4.OmniScan MX2 Training – Phased Array Calculator Review Question: What are the essential parameters for the phased array focal law calculator? 1. 1B2T9 .Questions or comments: [email protected] V4.com Free Download Manager.