Investigation of linear impact energy management and product claims of a novel American football helmet liner component

Impact Properties of Thiol–Ene Networks

“…The drop mass assembly of 5.6 kg contained a piezoelectric 88kN (20 000 lb) load cell tup and a customized 63.5 mm (2.5 in) diameter flat cylindrical steel drop dart to eliminate shear forces during impact. 24 The mass assembly was dropped from a height of 0.08 m resulting in an impact velocity of 1.25 m/sec and a total impact energy of 4.4 J. This energy was consistent with that used by Westerman and coworkers studying EVA, and they cite that this energy is capable of damaging portions of the orofacial complex.…”

Optimization of Additively Manufactured Multi-Material Lattice Structures Using Generalized Optimality Criteria

“…The overall structure also exhibits a symmetry over the spatial diagonals of each of the cells, which was not constrained. The horizontal members that are connected to the two support points are excluded from the optimization as they introduce singularities in Equation (13), resulting in total 548 structural members. The structure is comprised of 366 elements with E = 8.3 MPa, 85 elements with 8.3 < ≤ 10 MPa, 73 elements in the region of 10 < ≤ 544 MPa and finally 24 elements above 2900 MPa.…”

“…The development of high-performance, multi-material lattices for complex shapes has particular applications in, e.g., developing customized helmets for impact resistance [12,13]. Lattice structures are growing in interest due to their improved strength-to-weight ratio compared with stochastic foams alone.…”

“…Since the total volume of the helmet is constrained based on consumer needs, design decisions concerning material changes in the lattice are beneficial because they can alter the product's performance capabilities without altering its dimensions. The use of AM for producing the helmet is particularly beneficial, because it enables customized helmet shapes on a per-consumer basis such that the helmet conforms to a particular customer's head shape and has performance requirements that are tailored to particular applications [13,15,16]. Because of these considerations for the helmet, multi-material AM could greatly facilitate its design in comparison with conventional manufacturing approaches.…”

Cover Image

“…The cover image shows the Xenith X1e football helmet and its primary energy managing component, the Aware-Flow w 4 shock absorber, the performance of which was investigated by David E. Krzeminski et al (2011). The results and conclusions of this research are published in this double issue.…”