1. Supercomputing for your
desktop!
Finite Element Analysis of
Ultrasonic Phased Array
Inspections on
Anisotropic Welds
Paul ReynoldsPaul Reynolds
Weidlinger Associates IncWeidlinger Associates Inc
2. Contents
• IntroductionIntroduction
• Anisotropic Weld StructureAnisotropic Weld Structure
• Finite Element Modelling of InspectionFinite Element Modelling of Inspection
• Application of Total Focusing Method (TFM)Application of Total Focusing Method (TFM)
• Time Reversal Acoustics (TRA)Time Reversal Acoustics (TRA)
• Results of TRA and TFMResults of TRA and TFM
• ConclusionsConclusions
3. Introduction
• Weld integrity of the upmost importance in modernWeld integrity of the upmost importance in modern
industryindustry
• Exotic materials used more and more frequentlyExotic materials used more and more frequently
due to increasing performance demandsdue to increasing performance demands
• Anisotropic behavior of these complex materialsAnisotropic behavior of these complex materials
make conventional ultrasonic inspection methodsmake conventional ultrasonic inspection methods
unreliableunreliable
4. Introduction
• Semi-analytical models cannot adequately deal withSemi-analytical models cannot adequately deal with
extensive material boundaries that exist in suchextensive material boundaries that exist in such
mediamedia
• FEA offers potential for investigating performanceFEA offers potential for investigating performance
new ultrasonic inspection methods on thesenew ultrasonic inspection methods on these
structuresstructures
• Simulated inspection data can be readily comparedSimulated inspection data can be readily compared
to experimental data if availableto experimental data if available
5. Anisotropic Weld
• EBSD provides material/color map of weldEBSD provides material/color map of weld
dependent on dominant crystal orientation (40dependent on dominant crystal orientation (40
micron resolution)micron resolution)
6. Inspection Details
• 128 element piezocermic array:128 element piezocermic array:
• 0.5mm ceramic elements0.5mm ceramic elements
• 0.5mm polymer kerf = 1mm pitch0.5mm polymer kerf = 1mm pitch
• 1.5MHz centre frequency1.5MHz centre frequency
• Full Matrix Capture data processingFull Matrix Capture data processing
• Transmit on 1 element, receive on all othersTransmit on 1 element, receive on all others
• Repeat for all element to give 128x128 tracesRepeat for all element to give 128x128 traces
• 3mm diameter Side Drilled Hole defect3mm diameter Side Drilled Hole defect
• Array positioned directly on top of weldArray positioned directly on top of weld
• Weld represents join in a water filled pipeWeld represents join in a water filled pipe
7. FE Inspection
• Weld map can be read directly into PZFlexWeld map can be read directly into PZFlex
• Material properties of orientations calculatedMaterial properties of orientations calculated
in PZFlexin PZFlex
8. FE Details
• PZFlex is a transient code that can provide time-traces for eachPZFlex is a transient code that can provide time-traces for each
element’s response in the FMCelement’s response in the FMC
• Properties for each orientation calculated from stiffness matrixProperties for each orientation calculated from stiffness matrix
and rotational anglesand rotational angles
• Each element is effectively a unique model therefore can beEach element is effectively a unique model therefore can be
simulated as 128 separate modelssimulated as 128 separate models
• If paralleled all 128 models can be ran simultaneouslyIf paralleled all 128 models can be ran simultaneously
• Simulation for each element takes less than 1minute on a typicalSimulation for each element takes less than 1minute on a typical
workstation = < 90minutes totalworkstation = < 90minutes total
10. TFM – Isotropic Delays
• TFM focuses on every point in the imageTFM focuses on every point in the image
• Reflections from the grain boundaries can clearly beReflections from the grain boundaries can clearly be
seenseen
11. TRA – Delay correction
• Treat defect as a cylindrical source and record delaysTreat defect as a cylindrical source and record delays
• Reverse delays and use as elemental timings to create true focus through heterogeneous mediaReverse delays and use as elemental timings to create true focus through heterogeneous media
14. TFM with TRA delays
• Correct focal laws generate improved defect resolution,Correct focal laws generate improved defect resolution,
amplitude and positioningamplitude and positioning
• Everything outside the focus remains distortedEverything outside the focus remains distorted
15. 20dB Threshold Comparison
• Applying 20dB threshold removes grain boundary reflectionsApplying 20dB threshold removes grain boundary reflections
• TFM with correct TRA produces an image comparable to the ideal isotropic case at the defectTFM with correct TRA produces an image comparable to the ideal isotropic case at the defect
16. Conclusions
• Paul – thought I’d let you draw your ownPaul – thought I’d let you draw your own
conclusions as you’ll be presenting it.conclusions as you’ll be presenting it.
