Figure 4 | Helmet impact tests. (a) Standard helmet testing was performed using an Advanced Combat Helmet shell with state-of-the-art VN foam pads. (b) Forehead impact results demonstrating lattice pads that achieve a 36 g reduction in maximum head acceleration across two successive impacts as compared to VN foam. (c) Rear impact results demonstrating lattice pads that achieve a 47 g reduction in maximum head acceleration across two successive impacts as compared to VN foam.