Dynamic Testing Facilities
Dynamic testing of materials is a speciality of CEAM. Our facilities include custom-built split pressure Hopkinson bars, gas guns, and shock tubes of various sizes, as well as a high speed camera capable of 200 million frames per second.
CEAM has 5 sets of Hopkinson bars for testing the dynamic response of materials. The bars range in size from 3 mm to 76 mm in diameter and can be setup for uniaxial compression or tension as well as fully dynamic triaxial compression. Samples can be tested at temperatures ranging from -196 °C to +1000 °C with dynamic recovery of the specimens.
The wide range of Hopkinson bars allows for optimized tests of a variety of materials at strain rates ranging from under 100 /sec to 30,000 /sec. The 76 mm diameter bars are ideal for testing concrete and composite materials, where larger samples are required to be representative.
Gas guns are precision instruments for flyer plate and other impact experiments. The flyer plate experiments produce extremely high rates in exceptionally clean states of homogeneous strain. Available gas guns include a small moderate-velocity instrument of 60 mm bore, a large, high-velocity instrument of 56 mm bore, a 152 mm bore instrument, and a two-stage ultrahigh-velocity equipment. The 60 mm and 152 mm gun barrels are broached.
60 mm Gas Gun
- Up to 200 m/s impact velocities
- Micro-grooved barrel
- Normal and transverse displacement measurements by interferometry
- Normal velocity by interferometry
- Used for normal impact and pressure-shear experiments and momentum-trapped recovery experiments
56 mm Gas Gun
- Over 1000 m/s impact velocities Plate impact experiments
- Sphere and rod impact geometries
- Soft recovery system
- VISAR velocity measurement system
- Flash X-ray radiographic capability
152 mm Gas Gun
- 6 inch broached barrel
- Launches a 7 kg projectile at 200 m/s or a 1 kg projectile up to 400 m/s
- 5 m barrel includes a full vacuum experimental and recovery chamber
- Especially suited for both oblique and normal plate impact experiments
- Used for a "Penetrator Knife Test" which measures the dynamic fracture toughness of the skin of a large pressure vessel (e.g. the NASA Space Station)
- Suitable for impact testing of concrete and composite structures with large projectiles
1" Gas Gun
- Over 1100 m/s impact velocities for 11 gm projectiles
- Hadland Imacon 200 digital camera captures high-speed photography data
- Flash radiography and residual velocity measurement capabilities
- Used to study the ballistic performance and failure of various armor grade ceramic tiles with coatings
CEAM has developed two shock tubes to create shock waves in air. Both setups use pressurized helium and Mylar diaphragms to generate the shock waves.
4 in diameter bore shock tube
- Used to test the effect of shock waves on polymer coated structures
- Optional enclosed column for water or oil backing
1 in diameter bore shock tube
- Small size useful for tabletop experiments
- Integrated with Schlieren and shadowgraph imaging setup
- Used to investigate the interaction of shock waves with materials and small structures
A Hadland Imacon high-speed camera capable of capturing 16 frames at 200 million frames per second enables direct observation of a sample’s behavior during a dynamic experiment.
Schlieren and Shadowgraph Imaging
Paired with the high speed camera, this optical system allows us to observe variations in fluid densities within a test region. It is used to study the interaction of shock waves with samples and structures.