Dynamic Testing Facilities
Dynamic testing facilities include Hopkinson bars and gas guns. These instruments have been designed and chosen to provide the range of experimental capability required to support the scientific focus of the Center.
Hopkinson Bars
Extensive CEAM facilities for testing the dynamic response of materials include 5 Hopkinson bars ranging in size from 3 mm to 76mm in diameter. These include uniaxial compression and tension as well as fully dynamic triaxial compression. The facilities allow test temperatures ranging from -196C to 1000C 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 76mm is ideal for testing concrete and composite materials and we are currently adding the ability to do tension testing in this large size.
Gas Guns
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. 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 impact and pressure-shear experiments
- Momentum-trapped recovery experiments
- Normal and transverse displacement measurements by interferometry
- Normal velocity by interferometry.
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;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
- Is used for the "Penetrator Knife Test" which measures the dynamic fracture toughness of the skin of a large pressure vessel such as 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
- Presently used to study the ballistic performance and failure of various armor grade ceramic tiles.
