Measurement techniques

Laboratory tests

High performance instrumentation allows the measurement of deformations, displacements, forces, angles, pressures, temperatures, crack depth, etc. during a test at a precision that can be adapted to the particular situation.

Optical measurement systems can record entire displacement fields of small specimens for material tests up to displacement fields of full-size structural components. For this purpose, we use at present two systems:

  • Digital Image Correlation 2D and 3D (with a variety of cameras of different resolution)
  • NDI Optotrak Certus system with up to 500 markers

For measurements of the geometry of objects as well as the displacements of individual points, the Faro-Arm can be used. Examples of application are, for example, the measurements of displacements at different depths in a reinforced concrete slab.

For measurements of crack depth in metals, an Alternative Current Potential Drop system, ACPD CGM-7, with 64 channels is available.

Measurements of displacement field of an unreinforced brick masonry wall using the NDI Optotrak Certus System. From the displacement histories of four LEDs per brick the average strain state of each brick and the opening in the horizontal and vertical joints can be computed. The measurements of the complete displacement field give new insights into the deformation capacity of unreinforced brick masonry walls. Such walls are among the most vulnerable structural elements when subjcted to seismic loading.
Measurements of displacement field of stone masonry panel using digital image correlation (left). From the displacement field, the principal tensile strains are derived, which indicate the crack pattern (right).
Measuring the 3D displacement field on both sides allows computing the change in wall thickness due to splitting cracks.
Measurements of change in depth of a concrete slab using the Faro-Arm. From these measurements the crack openings at different ordinates within the slab can be derived.
Saw cuts of reinforced concrete slabs showing the holes that had been drilled for the crack width measurements by means of the Faro-Arm.

In-situ tests

X-Ray Radioscopy and Tomography Platform PIXE

The PIXE platform is designed to perform very high quality radiographic and tomographic imaging on a wide range of natural or engineered materials. It will provide researchers and students with quantitative and non destructive data on the density and structure of their studied materials.