Crushing a Coors Light in LS-DYNA
Crushing an empty can is one of life’s small satisfactions — and it is also a tidy little lesson in structural mechanics. That aluminum wall is barely 0.15 mm thick, and the way it folds into a neat accordion under your hand is the exact same physics that lets a car’s crumple zone soak up a crash. So we crushed one properly, in an explicit Ansys LS-DYNA simulation.
The physics: a thin wall doesn’t squash, it buckles
Push down on a can and the wall doesn’t compress like a solid block — it is far too thin for that. It buckles: the cylinder loses stability and snaps into a pattern of folds, and each fold is a traveling ring of plastic hinges where the metal yields and stays bent. That folding is the whole trick of energy absorption. A crumple zone, a crash barrier, an aircraft seat leg — all of them are tuned to fold progressively, turning kinetic energy into permanent plastic work in a controlled accordion rather than a sudden stop. The can is that mechanism in miniature.
Capturing it needs three ingredients an explicit solver provides: shell elements (you cannot afford to mesh
a 0.15 mm wall with solids), self-contact (so a fold lands on the fold beneath it instead of passing
through), and plasticity (so the deformation is permanent). LS-DYNA brings all three: four-node shells with
through-thickness integration points, single-surface contact, a *MAT_PLASTIC_KINEMATIC aluminum, and a
rigid wall pressed down at a fixed speed onto a fixed base. The result is the clean progressive crush above.
Reading the crush
Watch the animation closely and the collapse is anything but random. The first fold nucleates near the loaded end, where the wall is least supported, and each successive ring forms just below the last — the classic progressive folding pattern that makes thin-wall tubes such efficient energy absorbers. The force the wall carries spikes as each new hinge ring forms, then drops as it folds flat, producing the washboard force-displacement signature every crashworthiness engineer knows on sight. That near-constant average crush force over a long stroke is exactly what you want from a crumple structure: maximum energy absorbed, minimum peak load passed to whatever — or whoever — is behind it.
Have a thin-wall structure — a crash member, a pressure can, a panel — that has to fold, buckle, or absorb energy on purpose? Progressive-collapse and crush studies in LS-DYNA, cross-checked against theory and hand calculations, are core Rand Simulation work. That’s innovation through insight.
