Digital Image Correlation

Full fied monitoring of test coupons by Digital Image Correlation

Displays the global displacement and strain fields in X,Y,Z of the critical areas of structure submitted to mechanical loads.
This is the ideal technique to explore the behaviour of inhomogeneous and anistropic materials like composite materials as well as metallics.

  • W DISPLACEMENT

    Material : Metalic

  • Tensil test at high speed

    (100 mm/s)

  • EXY STRAIN

    Material : AI

  • MECHANICAL TEST

    Digital image correlation: Z-Displacement mapping

What is Digital Image Correlation ?

■ DIC is an optical method to measure the position of a field of points on a given surface.
■ From two successive images of the surface the 3D displacements and strains of the measured points can be calculated.

  Reference image
  Deformed image

Field of X, Y, Z positions
Field of X, Y, Z positions

 

Field of displacement U, V, W
Field of displacement U, V, W

 

Field of strain exx, eyy, exy
Field of strain exx, eyy, exy

 

Principle

■ 1 Speckle pattern painted and bounded on to the surface of the structure which follows its deformation.
■ 2 Cameras for stereos-vision.
■ 1 Software to correlate the information from the images.

DIC systems2

DIC systems3

Equipement

Vic 3D system and spotlights.

System set-up

Optical measurement : no contact with the structure.
The system is located around the structures.
The measurement can be remoted (up to 100 m or more)
■ Displacement fields (absolute or relatively to a state of deformation)
■ Strain fields
■ Statistics for each point of the image
■ Evolution of a point, profile in any direction, rotation

Example of results

Out of plane measurement with Line and point extractions.

Main Benefits

■ Whole field result map
■ Easy comparison with the FEM results calculated by the design offices.
■ The resulting datas can be retrieved in a dat file and loaded into any CAD software.