Direct numerical simulations of shock-to-detonation transition (SDT) in heterogeneous energetic materials
Abstract
It is well known that the sensitivity and performance of an energetic material (such as a plastic-bonded explosive or PBX) depends crucially on events at the microscale. A shock passing through the material will transition to a detonation over a run distance when chemical energy is added to the shock at myriad hotspots . Traditionally, the contribution of the sub grid hotspot thermo-mechanics was reflected in semi-empirical burn models, such as Ignition-and-Growth, SURF, CREST, HVRB, etc. While such multi-scale models employing scale-bridging techniques have shown success in predicting the sensitivity of energetic materials, there are several shortcomings that have come to light as the PI s group has pursued this line of attack. They include- 1. The separation of meso- and macro-scales in the scale-bridged (sequential) multi-scale approach does not provide physical insights into the thermo-mechanics of SDT as the shock evolves towards a detonation. While insights are obtained into hotspot formation and initiation, how these events couple and co-evolve with a shock to form a detonation is obscured due to the treatment of scales as distinctly separated, i.e., into meso- and macro-scales. 2. At each scale and in the scale-bridging surrogate model construction there are many assumptions and approximations that may lead to lack of control on errors and uncertainties as they propagate across scales. 3. In some scenarios the separation of scales into distinct meso- and macro- scales may not be valid, for example when the crystal (and void) sizes are large and the run distance is only a few crystal widths (as in HMX or RDX). This can easily happen in highly fractured microstructures (such as Class III HMX; Figure 3(b)) whereas scale separation may be more reasonable to assume in well-behaved microstructures (such as Class V HMX; Figure 3(a)).
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 06, 2025
- Source ID
- FA95502410481
Entities
People
- H. S. Udaykumar
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Iowa