Meaning
Experimental apparatuses facilitate the characterization of material behavior under high strain rates using stress wave propagation. Split hopkinson pressure bar is a testing system consisting of striker and incident bars along with transmitter components used to measure dynamic properties. A gas gun launches a striker into the incident bar to create a compressive wave.
This wave travels through the specimen, providing data on how it deforms at high speed.
Wave Propagation
Sensors attached to the metal bars record the strain as the pulse moves past. The incident wave bounces partially at the specimen interface while the rest passes through. Comparing these signals allows the calculation of the stress and strain inside the material.
Strain Rate
Deformation speeds reached in this test mimic the conditions of an explosion or a high-speed car crash. The split hopkinson pressure bar provides data that cannot be obtained from standard tensile testers. Adjusting the striker velocity changes the rate of the test.
Data Reduction
Mathematical equations transform the recorded voltage into a stress-strain curve. Accuracy depends on the alignment of the bars and the lubrication of the specimen ends. Variations in the split hopkinson pressure bar design allow for testing in tension or torsion.
Research facilities use these results to validate computer simulations of impact events. Detailed calibration of the strain gauges is required before every experimental run.
