FACILITIES

Extensive facilities are currently available in our laboratory for the characterization of mechanical properties of traditional (e.g. metallic) and advanced (e.g. ceramic, composite, functionally graded) materials. In all situations, loading rate can be varied over a large range. An overview of the HIGH STRAIN RATE MECHANICS LAB is seen below:

To determine the constitutive response at strain rates in the range 0.0001/s-1/s, servohydraulic and screw driven Instron or MTS machines are available. For strain rates around 10 /s a table top Drop Weight Tower is available

For loading at higher strain rates, in the range 100-10,000 /s, Split Hopkinson (Kolsky) bars (SHBs) are used. The HSRML is equipped with 3 compression and 1 tension SHB. Sets of compression bars made of C-350 maraging steel, 6061 aluminum, and Plexiglas are available, while in tension a steel bar is available. Each SHB is also equipped with momentum trapping and pulse shaping devices.

MTS Tabletop machine for Quasi-Static testing

Compression Split Hopkinson Bar

Tension Split Hopkinson Bar

For fracture characterization, strain gauge and optical techniques are available in our laboratory. An MTS table top testing machine mounted on an optical table provides quasi-static loading. A single stage gas gun is also available for dynamic loading. It can achieve impact speeds up to 150m/s.

Drop Weight tower

High speed diagnostic techniques:

We currently capable of conducting quasi-static and dynamic interferometric experimentation to study deformation and fracture of solids. Optical techniques include the CGS lateral shearing interferometer, photoelasticity, Twyman-Green interferometry and Digital Image Correlation (2D-DIC, 3D stereo-DIC and 3D Digital Volume Correlation). One Cordin 330 rotating mirror high speed camera is available for high speed photography applications at up to 2,000,000 frames per second. A Cooke hsfc pro ultra-high speed camera capable of up to 200,000,000 frames per seconds also available. These cameras serve as the imaging media in dynamic optical experiments. Two sets of high speed infrared detectors are also available for use in thermographic measurements during dynamic fracture and deformation. One set is an InSb the other a HgCdTe. Both have rise times around 0.5 microseconds or better. Data is recorded on several Tektronix and Agilent digital oscilloscopes.

For loading at rates in the range 106-107 /s a high power pulsed Nd:YAG laser is used. This laser is capable of producing a 50J pulse over a 20 ns duration.

Pulsed laser

High Speed IR detectors

High Speed camera

JOHN LAMBROS RESEARCH GROUP