1. Digital Image Correlation (DIC) is an optical full field measurement technique that can measure shape, deformation, and strain without contact. 2. DIC works by tracking subsets between images from two cameras to reconstruct the contour and calculate displacement and strain fields. 3. DIC has been used to measure major and minor strains inside and outside necking zones of plastics under tension, and to measure average strain of aluminum during edge stretching limit tests.

1. Project Experience

2. Introduction - DIC
2
Digital Image Correlation (DIC) is a full field, non-contact, machine vision
based optical measurement method which have the capability of measuring
contour (shape), deformation and strain.
Contour (shape)
Deformation
u v w
εxx εyy γxy
Strain

3. Fundamentals of 3D DIC
3
1. Subset tracking between two cameras.
2. Contour Reconstruction.
3. Calculating displacement field based on
contour subtraction.
4. Calculating strain field based on
displacement field.

4. Experimental of polymer plastic material
Major and minor
strain inside necking
zoom can be
measured from here.
Thinning strain
inside necking zoom
can be measured
from here.
Major and minor
strain outside
necking zoom can
be measured from
here.
Thinning strain
outside necking
zoom can be
measured from here.
Average strain inside four square
area is measured
3

5. Edge stretching limit test for aluminum by Digital Image Correlation
5
Measurement zone:
Coupon Thickness
Surface of the Notch

6. Strain Measure of Out-of-plane tear by Digital Image Correlation
6
First & last image from DIC Full-field strain information
Sample

7. Live Crack Strain Measurement using Stereo Optical System
7

8. Digital Shearography
8
Laser
Camera
Illumination direction Measuring
object
Observation direction
Measuring
Mirror
s
direction
P1
P2
P
CCD-Camera
Mirror 1
PZT-mirror
Frame
Grabber
PC
Amplifier

Light from P1
Light from P2

()
A clamped circular
plate loaded centrally
(-)
()
4
'
x w
x
 
 


  

2
[sin (1 cos ) ]
x u w
x x
 
 

 
   
 
( ' )
4
w
K
x x

 
 

   

If illumination angle is zero:
Strain component ∂w/ ∂x can be evaluated by measuring the phase ϕ.

'

,
4
where K
x

 


9. Shearographic NDT Test for Gate
9
Gate
Laser
Shearography
Sensor

10. Shearographic Testing Results
10
Live

11. Study of Impact Line and Skid Line Using Optical Method
11
The formation of skid & Impact line are all affected by clamping force,
bending angle, contact radius, and back force. But they appear on
different sides and position on a blank
Looking for Skid line
Here (With small
contact radius)
Looking for Impact line
Here (With big contact
radius)