Peering inside printed explosives using X-ray radiography

Additive manufacturing can assemble structures beyond those achievable by conventional manufacturing methods, leading to new designs and capabilities. For instance, additive manufacturing can produce high explosives that create directionally sensitive detonation waves. This method could produce safer, more targeted applications of explosives for military and industrial uses.

Brown et al. used flash X-ray radiography to characterize the detonation propagation and observe their propagation inside the charge. This technique allowed them to quantify the structure’s effect on the directionality of the wave.

“When we use X-rays, we can look at density changes and pressure changes through the bulk of the material,” said author Cameron Brown.

The team produced a structure composed of printed strands arranged either parallel or orthogonal to the direction of detonation wave propagation. These differently ordered strands can interact with the detonation wave in unexpected ways, and flash X-ray radiography can reveal the intricacies of those interactions.

“We’ve seen failure in the parallel oriented strands in other experiments in the past,” said Brown. “So we thought it would fail, but then we saw through the flash X-ray radiography that not only did it not fail, but actually those lower density regions were shocked to higher densities and ultimately higher pressures than the surrounding regions.”

The authors plan to continue their experiments to further explore the effects of more complex structures on high explosives. They hope that achieving a more robust understanding of the physics involved will lead to the development of safer and more controlled explosives.

Source: “Flash x-ray radiography analysis of detonation wave propagation in additive-manufactured high explosives,” by Cameron B. Brown, Laura B. Smilowitz, Dennis K. Remelius, Andrew M. Schmalzer, Bryce C. Tappan, Tariq D. Aslam, Seetharaman Sridhar, and Alexander H. Mueller, Journal of Applied Physics (2023). The article can be accessed at https://doi.org/10.1063/5.0146540 .