• Example: Strain distribution at a crack tip
  • Example: Tensile test of a round steel specimen
  • Example: Shear strain at a glue connection
  • Example: Compression of a metal foam
  • Example: Displacement around a crack
  • Example: Strain around a crack
  • Example: Bending of an aircraft wing
  • Example: 3D deformation of a shear test

Digital Image Correlation

Two digital cameras record the deformation process; the images are analysed with sub pixel accurate image correlation algorithms. For every object point (camera pixel) the 3D displacements and strain components (e.g. Exx, Eyy, Exy, E1 and E2) are calculated. Depending on the camera type, the system can be used for quasi static and highly dynamic events. The object's surface must have a stochastic pattern (natural or prepared). Rigid body movements are taken into account for the strain measurement.

 

Applications:

Material testing (Young's modulus, Poisson's ratio) at wood, metals, polymers,(metal) foams, rubber, composite materials.

Stability tests (component testing), tests with tensile test machines, validation of FEM simulations, crack propagation, dynamic tests.

 

Example: Deformation measurement with digital image correlation on a small gear tooth: The full field strain and displacement field is measured contactless. The results can be exported and analysed fullfied or extracted at discrete points of the measured surface.

 

Strain distribution on a gear tooth Size comparison of the gear tooth

 

System types Description Application
Q-400-2D 2D-DIC "Entry system" with one camera Measurement at flat specimen
Q-400-3D 3D-DIC Stereo system Measurement at all surface geometries
Q-400-RT 2D/3D Real time correlation For control applications
Q-400-MultiCAM Multi camera system Measurement up to 360° object surface
Q-450 System with high speed cameras For dynamic applications
Q-480 Handheld system For mobile testing on site

 

 

Technical Specifications (depending on the selected hardware):

Measurement field sizes 10mm² to 100m²
Accuracy for displacements 0,01 Pixel (e.g.: 1µm with 1MPixel-camera and 100mm measurement field width)
Accuracy for strain 200 µstrains (=0.02%)
Cameras 0,3 M Pixel to 16 M Pixel
Measurement rate 10 images/s up to 1.000.000 images/s