Shocking Results from Al Compression Experiments
Posted on: 09/28/2011
Using acceleration one trillion times faster than a jet fighter in a maximum turn, researchers have gained new insight into dynamic compression of aluminum at ultrahigh strain rates.
Using an ultrafast spectroscopic technique that tracks shocks on a time scale of ten trillionths of a second, Lawrence Livermore National Laboratory scientists measured breakouts in aluminum thin films with accelerations in the range of 10 trillion g's.
As noted in their recently published research, the Livermore team said that their experiments can test fundamental scaling laws on time and length scales where they may start to break down at strain rates that are orders of magnitude larger than previously examined. The goal of their efforts was to demonstrate that measurements on ultrafast time scales could achieve consistency with longer time scale experiments.
The researchers measured shock rises in aluminum and obtained shock stresses, shock widths and strain rates. They used the information to test the validity, at ultrahigh strain rates, of the invariance of the dissipative action, as well as the dependence of the strain rate on the shock stress.
Although the aluminum sample was completely destroyed at the end of the experiment, the team was able to observe it being compressed to 400,000 atmospheres in about 20 trillionths of a second.
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