Heavy Testing Machines
A 250 Tonne hydraulic forming press and 100 Tonne high-speed (up to 1.6 m/s) hydraulic forming press are available. These machines can act in tension and compression and can be used for three-point bending tests and forging tests. The 100 Tonne high-speed press can also be used for large scale fatigue tests. The machines can be fitted with furnace heaters that allow controlled high temperature testing (up to 1200 °C).
High Rate Testing Machines
There are 25 Tonne (up to 5 m/s) and 2 Tonne (up to 25 m/s) testing machines available for high strain rate tests. These machines are important for studying strain-rate dependent effects such as work hardening and can be used for ballistics research.
Gleeble Thermo-Mechanical Simulator
The Gleeble 3800 is a fully integrated digital closed loop thermal and mechanical testing system. Specimens can be heated at rates up to a maximum 10,000 °C/s by resistance heating, or can be held at constant temperature. It is capable of exerting up to 20 tonnes of static force in compression or 10 tonnes in tension, with applied displacement rates up to 2 m/s. Feedback consists of linear variable differential transformers, load cells or non-contact laser extensometry.
Optical Strain Mapping
The optical techniques available within the Centre include Digital Image Correlation (including Speckle and Grid Patterning), Electronic Speckle Pattern Interferometry and Moiré Interferometry. Digital Image Correlation provides 3D deformation mapping.
A wide range of X-ray diffraction techniques are available within Imperial College for the investigation of polycrystalline materials, single crystal and thin films. Samples may be examined in either bulk or powdered form. There is currently 2 PANalytical MRDs, 2 PANalytical MPDs and a Bruker D2 desk-top instrument for rapid data collection. There is also a high temperature X-ray diffraction facility. X-ray diffraction measurements can be performed at elevated temperatures up to 1000 °C using a combination of direct and indirect heating. This allows the investigation of the thermal behaviour of lattice parameters, crystallisation studies, and the detection and characterisation of high temperature phases. The high temperature chamber is fitted with a system to allow measurements to be made in controlled atmospheres (including oxidative) so that structural changes related to sample-gas interactions can be studied.
Imperial have been greatly successful in being awarded beam time at a number of research institutes including ISIS, UK; Helmholtz-Zentrum, Berlin; Institut Laue-Langevin, France; Heinz Maier-Leibnitz, Munich and The Paul Scherrer Institute, Switzerland. The highly penetrative neutron diffraction technique is well established for measuring 3D residual stresses deep within in a volume of material, non-destructively. Imperial have widely employed the technique to measure macro scale residual stresses and strains, typically in welded on non-uniformly plastic deformed components. These measurements have been valuable for the verification of finite element models to simulate the welding or deformation process and predict the residual stress fields. The method has also been employed to measure intergranular strains in alloys and used to develop and verify crystal plasticity models.