Ultrasonic method for the accurate measurement of crack height in dissimilar metal welds using phased array

• US 20070000328A1
• Filed: 01/06/2005
• Published: 01/04/2007
• Est. Priority Date: 01/06/2005
• Status: Abandoned Application

• Current Assignee: Jonathan Buttram
• Original Assignee: Jonathan Buttram
• Inventors: Buttram, Jonathan
• Application Number:
  US11/030,365
• Publication Number:
  US 20070000328A1
• Time in Patent Office: Days
• US Class Current: 73/597
• CPC Class Codes: G01H 5/00 Measuring propagation velocity of ultrasonic, sonic or infrasonic waves , e.g. of pressure waves
• CPC Class Codes: G01N 2291/0289 Internal structure, e.g. defects, grain size, texture
• CPC Class Codes: G01N 2291/0421 Longitudinal waves
• CPC Class Codes: G01N 2291/0422 Shear waves, transverse waves, horizontally polarised waves
• CPC Class Codes: G01N 2291/106 one or more transducer arrays
• CPC Class Codes: G01N 2291/267 Welds
• CPC Class Codes: G01N 29/069 Defect imaging, localisation and sizing using, e.g. time of flight diffraction [TOFD], synthetic aperture focusing technique [SAFT], Amplituden-Laufzeit-Ortskurven [ALOK] technique
• CPC Class Codes: G01N 29/07 by measuring propagation velocity or propagation time of acoustic waves
• CPC Class Codes: G01N 29/262 by electronic orientation or focusing, e.g. with phased arrays phased arrays per se G10K11/34
• CPC Class Codes: G01N 29/30 Arrangements for calibrating or comparing, e.g. with standard objects
• CPC Class Codes: G01N 29/4418 with a model, e.g. best-fit, regression analysis

Abstract

An ultrasonic method and apparatus utilizing phased array technology for obtaining accurate crack height measurements in materials where crystallographic structure creates beam reduction effects.

Claims

1. A method for measuring the through-wall dimension of a crack using an ultrasonic phased array system and time-of-flight simulation software, the method comprising the steps of:

providing first and second phased array transducers arranged in pitch-catch mode on opposite sides of the crack at a selected location corresponding to the focal zone of the transducer pair;

propagating focused sound waves from the transmitter transducer through a range of angles so that when combined with the corresponding range of focus locations generated by the receiver transducer, a focal zone is created from one side of the component, through the thickness, to the inspection surface,

receiving the tip diffracted signal originating from the crack tip

measuring the angle of propagation and absolute time-of-flight of the maximized tip diffracted signal

comparing the measured time-of-flight value with the theoretical time-of-flight value calculated for the measured angle of propagation according to the relationship

time-of-flight=(Wedge 1 Distance)/(Wedge 1 Velocity)+(Wedge 2 Distance)/(Wedge 2 Velocity)+Material Distance/Material Velocity

modifying the theoretical time-of-flight value by simulating beam redirection angles until it equals the measured time-of-flight value for the measured angle of propagation

determining flaw height through trigonometric relationships using the beam redirection angle in addition to the measured angle of propagation.

2. A method according to claim 1, wherein the transducer can propagate either shear or longitudinal wave modes.

3. A method according to claim 1, wherein the transducer is moved along the surface either manually or through motorized means in order to locate the location on the crack of maximum height.

4. A method according to claim 1, wherein the sector scan display produced by the phased array system is used for tip signal recognition.

5. A method according to claim 1, wherein the transducer arrangement can be changed so that the receiver is positioned directly over the crack location or adjacent to the transmitting transducer.

6. A method according to claim 1, wherein the transducer can propagate either shear or longitudinal wave modes.

7. A method according to claim 1, wherein the transducers used can be used with or without transducer wedges.

8. A method according to claim 1, wherein the transducers are mechanically held by an apparatus where the distance separating the transmitter and receiver is adjustable.

9. A method according to claim 1, wherein phased array system is portable.

10. A method according to claim 1, wherein the data can be stored and analyzed away from the inspection location.