Feasibility study on the use of a hierarchical lattice architecture for helmet liners

• Published in: Materials today communications 2018-03, Vol.14, p.312-323
• Main Authors: Khosroshahi, S. Farajzadeh, Tsampas, S.A., Galvanetto, U.
• Format: Article
• Language: English
• Subjects: Additive manufacturing; FEM; Helmet; Hierarchical lattice; PPE
• ISSN: 2352-4928; 2352-4928
• DOI: 10.1016/j.mtcomm.2018.02.002

[Display omitted] •A 3D hierarchical lattice structure has been designed and was additively manufactured for validating the FE model.•A helmet with a hierarchical lattice liner was tested virtually to compare its energy absorption capability with EPS foam.•The hierarchical lattice liner reduced the peak linear acceleration of headform by 44% compared to EPS foam, for direct impact.•The lattice liner reduced peak linear and rotational accelerations of the headform by 38% and 55% for oblique impact.•Assessment of biomechanical indicators showed that the lattice liner reduced the risk of brain injuries compared to EPS. Helmets are the most important piece of protective equipment for motorcyclists. The liner of the helmet is the main part of the helmet which dissipates the impact energy and mitigates the load transmitted to the head. Therefore, optimizing the material that absorbs most of the impact energy would improve the helmet’s protection capacity. It is known that the energy absorption of the helmet liner can be optimized by means of using liners with varying properties through the thickness, however currently the majority of used liners exhibit constant properties through the thickness. Advances in the field of topology optimization and additive manufacturing provide the ability of building complex geometries and tailoring mechanical properties. Along those lines, in the present work the feasibility of using a hierarchical lattice liner for helmets was studied. Finite element method was employed to study whether a hierarchical lattice liner could reduce the risk of head injuries in comparison to currently used liner materials. The results show that using a hierarchical lattice liner has the potential of significantly reducing the risk of head injury compared to a helmet with traditional EPS liner and could potentially be considered as the new generation of energy absorbing liners for helmets.