Helmets with lattice liners can mitigate traumatic brain injury from impacts

Area of Science:

• Biomechanics
• Materials Science
• Traumatic Brain Injury (TBI) Research

Background:

• Conventional helmet liners, such as expandable polystyrene (EPS), have limitations in mitigating TBI, particularly rotational acceleration.
• Architected lattice structures offer a novel approach to energy absorption in protective gear.
• Polyamide 12 (PA12) is a suitable material for additive manufacturing of complex lattice structures.

Purpose of the Study:

• To evaluate the effectiveness of PA12 architected lattice structures as helmet liners for TBI mitigation.
• To compare the performance of different lattice unit cell topologies (simple cubic, dode-medium, rhombic dodecahedron) against traditional EPS liners.
• To assess the impact on key biomechanical metrics, including brain tissue strains and intracranial pressure.

Main Methods:

• Utilized a high-fidelity finite element male head model for simulations.
• Simulated direct and oblique impact scenarios to mimic real-world head impacts.
• Measured mechanical quantities: maximum principal strain (MPS), shear strain, cumulative strain damage measure, and intracranial pressure at the brain tissue level.

Main Results:

• Lattice liners, particularly the dode-medium topology, demonstrated significant reductions in brain tissue strains compared to EPS liners.
• During oblique impacts, less than 1% of brain volume exceeded a critical MPS threshold with lattice liners, versus over 70% with EPS liners.
• Pressure-based assessments indicated superior performance of lattice liners over EPS in oblique impact scenarios.

Conclusions:

• PA12 lattice helmet liners show considerable promise for enhancing TBI mitigation, especially against rotational forces.
• The dode-medium lattice topology appears most effective among the evaluated structures.
• Additive manufacturing of lattice liners presents a viable advancement over current EPS technology for helmet safety.