Design, optimisation and analysis of a helmet made with graded honeycomb structure under impact load

Mechanical metamaterials for sports helmets: structural mechanics, design optimisation, and performance

“…2D extruded cellular structures, such as honeycombs (figure 5(A)), repeat periodically in two directions [398]. Honeycomb and tubular structures are studied frequently as energy-absorbing elements in sports equipment and helmets [23, [399][400][401][402][403], such as in Koroyd's helmet liner [31]. 3D periodic cellular structures, such as lattices, consist of unit cells repeating in three directions, increasing degrees of freedom during design, but also increasing manufacturing complexity and hence costs [395,397,398,[404][405][406][407][408][409].…”

“…When creating honeycombs, some variation can be applied in the extruded direction, as is the case of Miura-ori-inspired structures (figure 5 (B-ii)) [418,419]. Gradient metamaterials can also be developed by spatially varying unit cell parameters and properties [402,403,420,421]. These variations can be continuous or discrete (i.e.…”

“…Concerning some common topologies, hexagonal honeycombs are relatively stiff, with low density, for compression parallel to their extruded dimension [402,[425][426][427][428]. During impacts in the extruded direction, cell walls crumple and buckle [31,426], with densification occurring at ∼75% compression [402]. When impacted or compressed perpendicular to their extruded dimensions, honeycomb stiffness is lower [28, 402,427,429,430].…”

Materials in advanced design of personal protective equipment: a review

“…With the development of additive manufacturing, various complex hierarchical structures with microscale feature size could be facilely prepared [ [20] , [21] , [22] , [23] ] . The graded honeycomb structure could also be applied as a liner of a helmet, demonstrating nearly twice energy absorption rate and 37% lower transferred load compared to homogeneous honeycomb structure [ 24 ] . On the other hand, reinforcement of the foam structure by continuous cushioning fillers could efficiently improve the structural stability without much sacrifice in flexibility [ 25 ] .…”

Finite element-based optimisation of an elastomeric honeycomb for impact mitigation in helmet liners

“…The honeycomb is another example of an architecture cellular structure [14]. Combing properties such as high specific strength and stiffness [15], and excellent impact mitigating properties [16], the honeycomb has become a common design route to achieve lightweight structures with high energy absorption [17], [18]. The adoption of honeycomb structures within helmet design can improve user safety [19], [20].…”