3D Printed Impact Mitigation | Matter Assembly Computation Lab

Protecting fragile objects and people from impacts requires materials that can absorb energy without transmitting dangerous peak forces. Traditional foams are widely used because they are inexpensive and isotropic, but they collapse unpredictably and eventually densify under strain. Once densified, they transfer large stresses to the protected object.

In contrast, the ideal energy absorber, as first described by Ashby, has a square force–displacement profile: it compresses at a constant force across the full stroke, absorbing the entire impact energy without ever densifying. This “box-shaped” response is what we aim to realize through architected lattice geometries.

Our lab investigates plate lattice metamaterials as a promising path toward this ideal. By tailoring lattice geometry, we can design absorbers that respond predictably to impacts across a wide range of energies.

Diagram of a plate lattice — **Buckling plate lattice.** Wall thickness and pre-buckling can be used to tweak impact performance.

The ideal energy absorber has a box-shaped force–displacement profile (Ashby concept). Traditional foams densify under strain, while architected lattices can be tuned to approach the square profile.

Tunable Metamaterials for Impact Mitigation (2024)

In our 2024 paper, we demonstrated how plate lattice metamaterials outperform conventional foams in absorbing and distributing impact energy. By coupling additive manufacturing with a custom simulation pipeline, we established both experimental and numerical foundations for these structures.

Plate lattices absorb up to 6× more energy than foams of the same density.
They withstand impacts 10× more energetic while transmitting equivalent peak stresses.
Graded prebuckling increases energy absorption efficiency by ~10% on average (up to 25% in the best designs).
Unlike foams, which densify and lose effectiveness, plate lattices transmit near-constant peak stresses across a wide range of impact energies.

Our custom high-speed impact test rig validates the performance of these metamaterials by simulating real-world impact scenarios.

Impact performance: plate lattices maintain roughly constant peak stress while foams densify and transmit increasing stress — Impact performance of gyroid versus our Plate Lattice. Plate lattices maintain near-constant peak stress across increasing impact energies, unlike the gyroid that densify.

Automated Lattice Design

To push beyond case-by-case testing, we are building a design automation pipeline that links geometry generation, physics simulation, and optimization. This framework enables automated discovery of optimal designs for specific impact scenarios and constraints.

Produces Pareto spaces of candidate designs.
Supports rapid exploration at previously impossible scales.
Validates top designs experimentally with a custom high-speed impact test rig.

Diagram of the automated design pipeline — Schematic of the automated design pipeline integrating geometry generation, simulation, and optimization.

Pareto spaces of candidate designs generated by the automation pipeline. Strut-based lattices include Body-centered Cubic, Face-centered Cubic, Diamond, Kelvin Cell, and Re-entrant. Our plate lattices were tested using both graded pre-buckling and no grading. Each point in the graph represents a unique geometry, tested at two impact energies (7 joules and 70 joules). Such a large difference in energy is difficult for a single geometry to accommodate effectively. The plate lattices outperform the strut-based lattices, especially because they are tunable and hybridize better.