NDTnet - October 1997, Vol.2 No.10

Refining automated ultrasonic inspections with simulation models

by Michael Garton *

CHAPTER 1.
INTRODUCTION:
  • Potential Uses of Models
CHAPTER 2.
SCAN OPTIMIZATION PROBLEM STATEMENT

CHAPTER 3.
FORWARD MODEL TO EVALUATE SCAN QUALITY

CHAPTER 4.
MODELING EXAMPLES
CHAPTER 5.
CONCLUSION

DISCLAIMER/ACKOWLEDGMENT

REFERENCES CITED

CHAPTER 1.
INTRODUCTION

Potential Uses of Models

Table 1.
Examples of questions that can be answered with the models

1. Can ultrasound reach the region of interest?

  • What is the amplitude as a function of distance away from the transducer?
  • What is the amplitude loss when coupling into a particular material?
  • How much does the beam focus as it passes through a concave interface?
  • How does the beam bend as it mode converts?
  • How much does the beam spread as it propagates through the material?

2. What are the properties of the field in the region of interest?

  • What is the shape of the beam?
  • What is the phase curvature at a particular point?
  • Where is the focal point, if any, in the region?
  • Are there any regions of reduced amplitude in the inspection zone?

3. What is the response from the incident field on a given flaw?

  • What is the time domain waveform response for a particular flaw?
  • How does the flaw response change with probe orientation?
  • Given a calibration experiment on sample A, what will the response be of the same transducer on sample B?
CHAPTER 2. SCAN OPTIMIZATION PROBLEM STATEMENT

Objectives of the Modeling
Scope of the Modeling Modeling Inputs, Parameters, and Variables
Table 3.
Inputs, parameters, and optimization variables
Inputs:

  • longitudinal wave velocity
  • shear wave velocity
  • density
  • attenuation properties
  • maximum principal radius of curvature of the interface f(position)
  • minimum principal radius of curvature of the interface f(position)
  • reference signal amplitude
  • size, shape, and orientation of the flaw
  • top of inspection zone, bottom of inspection zone
Parameters:

  • probe center frequency
  • probe crystal shape (square, rectangular, circular, and elliptical)
  • probe size
  • probe focal type (planar, cylindrical, spherical, and bi-cylindrical)
  • probe focal lengths
  • wave type (longitudinal or shear)
  • material properties of couplant (velocities, density)
  • incident angle (restricted by critical angles)
  • water path
Optimization variables:

  • scan step size
  • index step size

Solution Strategy

Problem Classification Go to other Chapters: CHAPTER 3. FORWARD MODEL TO EVALUATE SCAN QUALITY
|Top to this page|

| UTonline |
© Copyright 1. Oct 1997 Rolf Diederichs, rd@ndt.net
/DB:Article /DT:tutor /AU:Garton_M /CN:US /CT:UT /CT:modeling /ED:1997-10