Head: Dr.-Ing. Jens Gibmeier
Building 10.91, Raum 025-030
- 16 Diffractometers for X-ray stress analysis
- 14 conventional setups for
stress measurements on crystalline materials using the sin²psi method.
retained austenite analysis of steels using the 6-line-method
- 2 high-performance setups equipped with rotational anodes and area detector for
stress and phase analysis with high spatial resolution
analysis of steep stress gradients,
Depth profiling of residual stresses via stepwise removal of surface layers by means of electrochemical polishing
- in situ devices for the x-ray diffractometers
- 4-point bending rig
- tension/compression loading rig
- specimen furnace for temperatures up to 1200°C
- devices for gyrating or translating the sample under investigation in order to increase the grain statistics
- Hole-drilling device for residual stress measurements
- Blind holes with diameters 0.8 or 1.6 mm
Measurement campaigns at synchrotron or neutron radiation facilities
A number of questions cannot be solved in our own laboratury using the conventional experimental setups described above. Therefore we frequently perform measurements at synchrotron radiation facilities (higher flux, less divergence, white spectrum or tuneable wavelength) or neutron radiation facilities (strongly increased penetration depth). Many of our measurement campaigns are carried out at the synchrotron radiation facilities HASYLAB (Hamburg), BESSY (Berlin) and ANKA (Karlsruhe) and at the neutron reactor of the Institut Laue-Langevin (ILL) in Grenoble
Resonant Ultrasound Spectroscopy (RUS)
The resonant vibrations of simply shaped specimens (parallelepipeds, cylinders) are analyzed in order to analyze the elastic constants of the specimen material.The specimen under investigation is placed diagonally between two piezoelectric transducers. The transmission spectrum is recorded over a broad frequency range. By means of an iterative computer algorithm up to nine independent elastic constants are computed.
Ultrasonic phase spectroscopy (UPS)
The ultrasonic transmission spectrum is measured on a sample exhibiting plane and parallel faces. The phase lag produced by the specimen is measured as a function of frequency. The wave velocity can be computed from the resulting phase spectrum. By analyzing the velocities of longitudinal or shear waves up to 6 independent elastic constants can be measured on a single parallelepiped specimen. This technique is specifically suited for strongly attenuating materials (such as materials exhibiting substantial porosity or microcrack density).