Monday  |  Executive CD  |  11:40 AM–12:00 PM

#19577, High-temperature Dynamic Strength of Pure Aluminum under Ultrahigh Strain Rates

The dynamic yield strength of metals and alloys generally decreases as temperature increases.
However, some metals (one such being aluminum) have been observed to exhibit an anomalous
rise in the Hugoniot elastic limit (HEL) with temperature at high strain rates. This study seeks to
unravel the relationship between temperature and dynamic yield strength of aluminum under high strain rate loading. To study this unusual behavior, a small-scale Hopkinson bar with high temperature is developed. An IR camera is used to determine specimen temperature; a microcontroller regulates a power supply to control the heating of the specimen and the firing of the striker bar. PDV is used to optically measure the response in the bars to determine the stress, strain, and strain rate of the specimen. Experiments are conducted on pure polycrystalline aluminum at strain rates varying from 10^4 to 10^5 /s and temperatures ranging from 100 to 500 C. The stress-strain response of pure aluminum is discussed and compared with the existing literature.

Isaac Faith Nahmad   University of Minnesota-Twin Cities
Mouliswar Ramakumaresan   University of Minnesota-Twin Cities
Daniel Casem   Army Research Laboratory
Suraj Ravindran   University of Minnesota-Twin Cities