One of the genuinely transformative capabilities additive manufacturing brings to defence is the ability to produce engineered lattice structures: precisely tuned, three dimensional cellular geometries that absorb impact energy in ways no foam or solid material can match. Helmet liners, vehicle blast attenuators and equipment cushioning are all being rethought around this capability.
The science is mature, the design tools have caught up, and Australian defence and PPE programs are starting to integrate lattice based protective elements into platform and personal protection work. Here is a quick tour of what actually matters.
Why lattices outperform traditional foam
Traditional impact foams such as polyurethane, EPP and EPS work by crushing: the cells collapse and absorb energy as they go. They are cheap, well understood and effective up to a point. The limitation is that their response is fixed by the grade you pick. A printed lattice can be tuned across a single part, region by region, without changing materials.
That single change unlocks a different design conversation. Instead of selecting one foam density and accepting compromise everywhere, the engineer can map an absorption curve onto the part exactly where it is required.
Foam crushes uniformly; lattices can grade stiffness across regions,
Cell geometry, strut thickness and orientation are all design variables,
Different threat zones (crown, occiput, sides) can carry different response curves,
Mass can be removed where protection is not required,
Designs can be reissued via FDM printing without retooling.
Common lattice families
Three families dominate practical engineering work, and most production designs end up as a hybrid of the three.
Gyroid: smooth triply periodic minimal surface, excellent omnidirectional response,
Octet truss: high stiffness to mass, suited to compressive loads,
Re-entrant honeycomb: auxetic, with distinctive negative Poisson behaviour,
Graded honeycomb: tunable across the part for layered protection,
Hybrid lattices: combinations chosen region by region within a single component.
Materials that actually survive impact
A lattice only works if the polymer absorbs energy plastically without shattering. Source filaments through a controlled supplier like OzFDM so that material lots are traceable from the print run back to a certificate, and so that the right ductile grade is in the spool when test season arrives. For PPE work, biocompatibility and skin contact considerations narrow the practical list further again.
Glass fibre nylon (PA-GF): ductile and strong, the workhorse for blast attenuators,
TPU 95A and softer grades: flexible cushioning and skin contact layers,
Polycarbonate (PC): tough engineering grade for structural lattice work,
Avoid: carbon filled grades, which tend to store energy elastically rather than absorb it,
For PPE: medical grade nylons and TPU narrow the practical list further.
Validation that actually counts
FEA is a useful first pass, but real lattice behaviour is shaped by layer adhesion, infill stitching and post processing. Physical test is non negotiable for any protective application, and the test regime should be agreed with the end user before the first lattice is printed.
Drop tower testing for energy absorption at calibrated heights,
Instrumented headforms for helmet liner assessment,
Quasi static compression for baseline stiffness curves,
Repeated impact cycling to confirm degradation behaviour,
Coupons printed alongside production lots for material traceability.
KEY TAKEAWAYS
Lattices let designers grade protection across a single part,
Gyroid and graded honeycomb dominate impact work,
Ductile polymers absorb energy; carbon filled grades usually do not,
Physical impact testing is essential, not optional,
Talk to us via the quote system to scope a lattice protection program.