Viscoelastic circular cell honeycomb helmet liners for reducing head rotation and brain strain in oblique impacts

Fady F. Abayazid, Mazdak Ghajari

Materials & Design, 2024

Abstract

Rotational head motion is one of the major contributors to brain tissue strain during head impacts, which damages axons and vessels and leads to traumatic brain injury. Helmet technologies have come to market promising enhanced protection against such rotational head motion. We recently introduced novel air-filled viscoelastic cell arrays and showed that their shear response under oblique impacts can be tailored through altering the cell wall curvature. We found that concave cells provide shear stiffness that is a few folds larger than that of convex cells. Here we test whether altering the cell curvature can reduce head rotational kinematics and brain strain and whether the viscoelastic cell arrays outperform the reference EPS foam-based liner. To test these hypotheses, we incorporate the viscoelastic cell arrays in a bicycle helmet liner. We use validated finite element models of the helmet and replace the liner with validated finite element models of the cellular cell arrays. We simulate oblique impacts at different locations to represent a wide range of real-world bicycle head impacts. In all cases, the head kinematics and brain deformation metrics indicate significant…

Cite as (BibTeX)

@article{abayazid-2024-viscoelastic-circular-cell-honeycomb,
  title={Viscoelastic circular cell honeycomb helmet liners for reducing head rotation and brain strain in oblique impacts},
  author={Fady F. Abayazid and Mazdak Ghajari},
  journal={Materials & Design},
  year={2024},
  doi={10.1016/j.matdes.2024.112748}
}