Research Lab

Structures Laboratory

The Structures Laboratory Eindhoven is well-equipped for testing structural elements, components and systems of various materials. The laboratory experiments for fundamental research are mainly performed in order to calibrate finite element models for simulating the structural behavior of the specimens. This allows the researchers to perform parameter studies with the help of finite element computer programs with the ultimate goal of developing design rules and guidelines for the structural system under investigation.

Research Facilities

  • 2 Cranes of 5000 kG (total 10000 kG)
  • Facilities to prepare specimens or test accesoires
  • Digital Control Systems to operate Hydraulic jacks
  • Measurement equipment to scan and store sensor data
  • AccelerationTemperatures and humidity
  • Strains
  • Deformations (Analog - Digital and Optical (ESPI = Electronic Speckle Pattern Interferrometre)
  • Forces
  • Sensors to measure
  • Climate controlled rooms 9 * 12 meter and 2 * 2 meter
  • Variable system to construct test setup
  • Hydraulic pump system (20 and 80 liters/min to control hydraulic Jacks
  • Tension tests up to 400 kN
    • 250 kN Tension - Compression machine Instron
    • 100 kN Tension - Compression machine Schenk-Instron
    • 250 kN Tension - Compression machine Schenk-Instron
    • 400 kN Tension - machine Schenk-Intron
  • Compression tests up to 5 MN
    • 4 MN Compression machine Form + Test
    • 2.5 MN Compression machine Schenk - Instron

Electromechanical Machines

Electromechanical universal testing machine

Electromechanical universal testing machine. Advanced Video Extensometer. Loadcells 250kN & 5kN.

Schenck 100kN Machine

Static testing in a tensile or compression mode. Position Controlled. Force Controlled. Strain Controlled.

Schenck 250kN Machine

Static testing in a tensile or compression mode. Position Controlled. Force Controlled. Strain Controlled.

Hydraulic Machines

2.5MN Compression

High-capacity servohydraulic system can be used for quasi-static tests. Position Controlled. Force Controlled.

4 MN Compression

Material testing machine. Force Controlled.

400 kN Tension Machine

Material testing machine. Position Controlled. Force Controlled.

Projects

Buckling test of a High Strength Steel-Glass Column

The buckling of the slender steel column is suppressed by assembled glass panes.

Bending Shear Interaction of I-shaped Steel Sections

Experimental research to determine the bending – shear interaction of rolled I-shaped steel sections.

Shear Calcium Silicate masonry

The behavior of H-shaped calcium silicate masonry specimen loaded in shear.

Moment Transfer in Timber connection

Research on the moment transfer in timber connection with steel plate connectors, ‘densified veneer wood’ and tube fasteners.

Splitting of Timber beams

Splitting of timber beams caused by multiple connections along the beam span.

Bending behavior of Glass panes

Cold bending behavior of glass panes by lateral buckling.

3D printing of Concrete

The research group is called 3D Concrete Printing (3DCP).

Steel fiber reinforced Concrete

Properties of steel fiber reinforced concrete in combined tensile and bending mode.

Welded Aluminum truss

Bending test on a welded aluminum truss.

The Laboratory owns dedicated data-acquisition systems as well as more general systems for controlling and monitoring experiments. Depending on the character of an experiment a choice can be made between a wide range of sensors with its own specific range and accuracy

A variety of Data Acquisition Systems are available in the Laboratory. Depending on the Desired Accuracy, Sample speed, Amount of sensors in an experiment and type of sensors Laboratory Staff will advise which system to choose. Typical maximum specifications are:

  • Up to 18 bit resolution
  • Up to 666 kS/s Input
  • Up to 2.8MS/s output
  • Up to 156 Sensors in 1 system (limitations in type of sensors).

cRIO controller used for motion sytems in the Active facades research.
MOOG and Instron systems to control Hydraulic cylinders.

For most experiments standard Lab software is suitable, for special measurement and control functions dedicated software can be developed. Also special tools are available to monitor vibrations, measure accelerations and process image Acquisition.

Data acquisition

Sensors

Example of a Rosette (3-direction) Strain Gauge. Most often measured variables during an experiment are Forces, Displacements, Strain, Acceleration, Rotation, Temperature and Humidity.

High speed camera

High Speed Camera Used in Glas Panel Experiment To view and monitor fast events a high-speed camera is available, Up to 5000 Frames/sec with a resolution of 512*512 (Higher speeds are possible with reduces resolution).

ESPI Device

ESPI stands for Electronic Speckle Pattern Interferometer, and is a device to measure 3D deformation and Modal Analysis. ESPI is a non-contact 3-D displacement measurement system which covers a complete area up to approximately 25 * 20 cm.

Measurement principle

Test conditions
If ESPI is required, the test conditions have to be determined.
Some important boundary conditions and properties:

  • Maximum surface area 20 * 20 cm
  • Minimum surface 3*3 mm (macro mode)
  • Surface has to be optically rough
  • Vibrations can cause bad measurements or instability of the test setup, a room with no vibrations is preferred. Vibrations generated by the test itself must be damped if possible
  • ESPI measures the displacement difference of a surface, if body motion occurs it is difficult to determine small displacement differences, as well as the strain in the measured area (special test setup with attachment of the ESPI-head to the material can be a solution)
  • If an experiment contains more than one material with a different optical reflection, no uniform illumination is possible, special spray is available to prepare these specimens
  • Export facilities are available for post process of data.

The surface of a specimen is illuminated from two positions with coherent laser light in various phases of testing.
The speckle interferometry uses the interference characteristics of electromagnetic waves. It is based on the fact that an optically rough surface appears granulated when it is lit by an coherent light (laser). This phenomenon is called a speckle and the individual grains are termed speckle.
After each load step, the reflected light is captured with a CCD camera. At first a speckle pattern is found, which includes the deformation information of each point of the measured object. By subtracting speckle patterns from various phases of testing, interference fringes are formed. The number of fringes and their widths are a measure for the displacements of the illuminated area.
3D-Displacement and strain distribution can be determined with a resolution of 10 nm or 1 µm/m.
Automatic evaluation of the measurement by real-time subtraction and phase-shifting algorithms is possible. Changing the polarity of the laser, displacements in X, Y and Z direction can be obtained. To compare speckle patterns and to establish strains from measured displacements special computer software is available.