A universal threshold found in shock wave physics

Shock waves are commonly used to study materials in fields like fusion energy and planetary science. Materials respond differently to strong and weak shocks, with a dramatic change in shear support as stresses increase, but despite decades of research, no universal explanation has emerged for when this transition occurs.

In hopes of developing a physical framework and improving shock physics predictability, Neil Bourne studied this boundary where a change in shear support is seen, called the weak shock limit (WSL). Analyzing different materials, such as metals, organic crystals, and brittle solids, Bourne looked for patterns in the materials’ response to shockwaves of varying compression pressures. The results identified a common transition point that appeared across all the materials.

“The most exciting aspect is that what initially appeared to be behavior unique to individual materials instead seems to reflect a universal physical threshold,” Bourne said. “If further studies confirm this interpretation, it provides a unified framework for understanding shock-wave behavior across metals, ceramics, polymers and many other materials.”

The results could mark the beginning of a move towards predictive shock physics, Bourne said, as the WSL could be the first experimentally established member of a wider hierarchy of physical thresholds governing material behaviors.

Bourne plans to continue studying whether such universal thresholds exist at higher shock pressures, associated with structural collapse, chemical reactions, and eventually electronic and plasma states. Results from this work could help in creating a common scientific framework for designing experiments, interpreting results, and developing predictive constitutive models across the field of shock physics.

Source: “The weak shock limit as an organising boundary in shock response,” by Neil K. Bourne, Journal of Applied Physics (2026). The article can be accessed at https://doi.org/10.1063/5.0339565 .