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Physics and Chemistry of Solids

Experimental study of dynamic behaviour at short timescales

As an experimentally-driven research group, our laboratories are at the core of what we do. Some of our equipment is off-the-shelf, but most of it is either partially or fully designed and constructed in-house. We also regularly re-configure, re-design, adapt and update our equipment as required for each research programme. While we endeavour to keep this page updated, it can only ever cover a fraction of our current experimental capabilities, and we are continually looking to expand and improve our offering.

In addition to working in the laboratory, a number of the pieces of equipment can be taken off site for use either in demonstrations or to instrument large scale experiments.


Experimental facilities 

Light gas guns

We have a 50mm bore Plate Impact Facility. A single stage light gas gun, capable of launching projectiles at up to around 1km/s. Initially designed and constructed in the 1990s, in the early years it was used to determine shock Hugoniot data for a wide range of materials. Nowadays the suite of potential experiments has expanded to include the study of off-Hugoniot, ring-down, release, spall and other related shock phenomena, as well as experiments with more complex geometry.

Our ‘small’ light has gun is a separate system with interchangeable barrels. These have a range of bore sizes from 5mm to 25mm and a maximum firing velocity of 1500 m/s for a 15g (or lighter) projectile. Normally the barrel is matched to the diameter of the projectile required, thus avoiding the challenges of ‘sabot stripping’. Target chambers may be evacuated or atmospheric, with a wide array of bespoke options to facilitate novel experiments.


Hopkinson Bars

The group has a suite of bars, both compression and tension. We have a wide range of bar lengths, diameters and materials (from maraging steel to magnesium). Recent developments range from down-scaling towards “micro” bars, direct impact configurations, non-contact interferometry probes in place of adhered gauges, off-ambient (both heated and cyrogenic) loading, and new methods for characterising necking strain under tensile load.


Dropweight & BAM tester

The Dropweight is another in-house designed facility, able to launch a 5.5kg weight under gravity at up to around 5m/s, offers a complementary dynamic loading scenario to Hopkinson Bars. In a typical experiment a specimen is compressed between toughened glass anvils, producing a maximum impact pressure in the specimen of approximately 1 GPa. Diagnostics include force transducers, a periscopic arrangement to allow for high speed photography (for example to look at hot-spot ignition of energetic materials) through the glass anvils, and a variety of analysis techniques including spectroscopy and mass spectrometry. The BAM tester provides a complimentary ‘standard’ test for energetic sensitivity.


Instron mechanical testing

Our new Instron 68TM50 is a low strain rate screw-driven mechanical testing machine. Samples may be tested in tension or compression, and a variety of fixtures (including peel, multi-point bending and Brazilian Disk) are available. We have 50kN, 5kN and 500N load cells, suitable for testing small high-strength metal specimens through to very soft polymers. The attached environmental chamber enables experiments between -100C and +350C, and diagnostics include an AVE2 digital extensometer as well as clip-on gauges and Digital Image Correlation (DIC) capabilities.


Solid particle erosion

The solid particle erosion facility consists of a long tube connected to the laboratory high pressure air system. Sand or other solid particles are introduced via a venturi section in the tube, and the flow of sand can be controlled via a hopper system so that the erodent flux is well known. Different barrels are available for the system to alter the area of target being eroded and the velocity range (which is around 200 m/s maximum). A wide range of carefully particle sized sand fractions are available and the target chamber is fitted with an industrial vacuum cleaner so that silica dust cannot escape into the laboratory. As well as standard erosion experiments, the facility has also been used to examine phenomena such as light emission from high velocity sand impact on helicopter rotor blades.


Liquid drop erosion

The liquid erosion facility consists of two separate pieces of equipment, the Single Impact Jet Apparatus (SIJA) and the Multiple Impact Jet Apparatus. The SIJA uses a small gas powered gun to fire a single pellet into a reservoir of water which has a small hole on the opposite side to the impact face. The pellet compresses the water and forces it out of the hole as a jet. Owing to the air resistance this jet becomes hemispherical in flight and therefore approximates a drop when impacting the target surface. Velocities of up to 1200 m/s can be reached. The MIJA utilises the same principle, but incorporates a multiple shot capability and computer control. This has allowed similar machines to be produced for industrial use.


Laser-launched flyer

We have an experimental laser-launched flyer system.  This consists of a Q-switched Nd:YAG laser with a half-joule pulse energy, and an array of optics to condition, analyse and focus the beam.  The focussed pulse falls on a film a few microns thick and supported by a transparent substrate.  The area irradiated is of order a square millimetre.  The high energy density in this region converts a thin layer of the film to plasma, driving the remaining thickness forward at speeds of a few kilometres per second. 


Materials characterisation suite

  • TA Instruments Discovery 850 DMA (0.001 to 200 Hz, -150 to 600°C)

  • JKR adhesion apparatus (bespoke)

  • Thermal expansion apparatus (bespoke, designed for inert & energetic composites)

  • 30 ton press

  • Hot Disk TPS 250 S thermal transport property meter

  • Spark tester

  • Kruss tensometer

  • Keyence optical microscope

  • Analytical balances, including density measurement

  • Labram acoustic mixer

  • Erweka AR 401 planetary mixer

  • Edwards evaporator


High-rate diagnostics

  • Oscilloscopes (including 6 channels at 1GHz, and 4 channels at 8GHz)

  • Phantom 6410 high speed camera (up to 1.5M FPS)

  • Phantom 1610 high speed camera (up to 1M FPS)

  • Phantom 4.3 high speed camera

  • Ultra UHSi IVV digital framing camera (up to 200M FPS, 12 frames)

  • 675 streak camera

  • Up to 8 channels of PDV laser interferometry (both het- and homodyne)

  • 3 beam VISAR

  • 150kEV, 70ns flash x-ray

  • Shock temperature measurement methodologies (fast thermocouples and pyrometry)

  • Princeton Instruments gated spectrometer

  • Highly image intensified spectrometer (down to single photon emission events)

  • Contact gauges (Manganin stress gauges, PVDC, Kistler & amplifiers)


We also have access to a plethora of shared facilities across the Department of Physics, and the University of Cambridge, ranging from mechanical testing to electron microscopy and X-ray tomography