Predictive Science

Predicting the mechanical, detonation, and safety properties of complex energetic materials

Energetic materials are critical components of systems that play a key role in our national security mission. However, it can be extremely difficult to understand and predict the complex behavior of energetic materials, where reactions can take place in microseconds and multiple physical and chemical mechanisms affect these reactions. In response to these challenges, LLNL scientists develop and refine our ability to predict the behavior of energetic materials across a wide range of environments, which in turn enables us to design more effective, inherently safer components and systems.

Predictive Model Development

We develop unique mechanical, safety, shock initiation, and detonation models. Leveraging insight into the underlying chemical and physical processes enables us to develop accurate models and codes that are applicable to as many scenarios as possible. For example, we develop models and codes that enable us to explore quasi-static mechanical loading, mechanical and/or thermal insult during an accident, shock loading, and component end-of-life performance.

Model Validation

We use sub-scale simulations to inform continuum models, while performing experiments that probe the underlying physical mechanisms. Where gaps exist, we create diagnostics and develop new techniques to probe chemistry, material physics, and operative mechanisms. For example, we conduct laser-driven dynamic compression experiments to validate explosive reactive flow models, and we develop high-resolution optical diagnostics to study initiation systems.

Research Highlights

LLNL’s multidisciplinary approach to predictive science combines highly diagnosed experiments with powerful simulation and modeling tools to study energetic materials. Examples of our research include:

• Developing Cheetah, a powerful computational tool that enables us to model and predict the complexities of high explosives at a fundamental physics and chemistry level, accelerating our ability to assess and optimize the performance of candidate materials and system configurations.
• Conducting billion-atom molecular dynamics simulations on LLNL’s Sierra supercomputer to determine the anistropic dynamic strength of TATB (1,3,5-triamino-2,4,6-trinitrobenzene) high explosives, allowing us to develop more advanced models of high explosive shock initiation.
• Conducting experiments at x-ray facilities, where we study detonation physics at unprecedented length and timescales. For example, we explore new ways to capture x-ray images of small-scale detonations, and we characterize detonation products using advanced microscopy and spectroscopy.
• Developing the Livermore Insensitive High Explosive Material Model to assess the mechanical performance of energetic materials over time, in a variety of environments. We conduct large-scale mechanical testing of the material to validate the model, providing insight into a system's structural performance over its lifetime.
• Developing LLNL’s High Explosive Response to Mechanical Stimulus model, which enables us to predict post-ignition responses of energetic materials under various hazard scenarios.

Featured Collaborations

We collaborate with colleagues at academic institutions to expand our research scope and foster opportunities for early career scientists to engage in national security research. Examples include collaborating with leading research institutions to:

• Explore ways to use reactive molecular dynamics to simulate the fundamental mechanisms of ignition in shocked energetic materials.
• Study the dynamic compression of high explosive crystals.
• Perform high strain-rate testing to determine the mechanical properties of polymers.

Related Resources

LLNL’s ultrafast imaging capability, known as the High Explosives Laser Imaging Optical System, captures high-speed images of detonators and initiators. By analyzing these images, scientists can validate hydrodynamic models of detonation phenomena.

Our laser-driven x-ray diagnostics enable researchers to study dynamically compressed explosives, including the formation of reaction products, and then use that experimental data to validate models.

Experiments to support predictive science take place at LLNL’s High Explosives Applications Facility, where researchers test and evaluate novel concepts at the lab scale using high-speed diagnostic tools.