Characterizing the Break-up and Reaction of Fragments upon Rapid Impact

In a collaborative effort with the Hopkins Extreme Materials Institute (HEMI), The Defense Threat Reduction Agency (DTRA), and the Army Research Laboratory (ARL), we are developing analytical tools and techniques to image and analyze materials undergoing hypervelocity impacts. We utilize these tools to observe events at millions of frames per second, examine how materials fragment upon impact and predict how those fragments will ignite and combust. For instance, we compare wrought materials to compacts formed through swaging (radial forging).

Figure 1.
Figure 1. From left to right: 5mm Al sphere machined from a cast/rolled plate, a 5mm Al cylinder machined from a cast/rolled plate, a 5mm Al cylinder made from swaged 175 um Al particles, a 5mm Al cylinder made from swaged 15 um Al particles.

The videos below compare the hypervelocity impacts of a wrought Al cylinder (top) to a cylinder made from swaging 175 um Al powders (bottom).

High-Density Reactive Materials for Structural Applications

This project collaborates with the Army Research Laboratory (ARL) and the Air Force Research Laboratory (AFRL). Utilizing a combination of ball milling and rotary infeed swaging, we are creating fully dense compacts of composite microstructure reactive materials. We seek to understand the mechanical properties of the materials and utilize those properties to inform the processing parameters. This research focuses on applications in counter-WMD development, commercial joining operations, and oil/gas well monitoring.

Figure 2
Figure 2. Example of a structural reactive composite material, where the core is swaged high density reactive powders, and the outer shell is copper.

We employ the same kinds of hypervelocity experiments with novel diagnostics to study the fragmentation and combustion of fragments of these structural reactive composites, as shown in the figure below.

Figure 3
Figure 3. Impact of a high density reactive compact on a steel anvil recorded by high-speed videography (left), as imaged via high-speed videography through a triple-notch filter (middle), and transformed into a temperature map via three-color ratio pyrometry (right).

Researchers