Multi-scale comparative analysis of 3D random fiber composites for industrial helmet shell applications

This paper investigates the replacement of conventional High-Density Polyethylene (HDPE) shells in industrial safety helmets with 3D randomly oriented fiber-reinforced composites. A multi-scale finite element framework is developed, coupling micro-scale Representative Volume Element (RVE) homogenization with macro-scale thin-shell simulations. Several analytical micromechanics bounds are compared against high-fidelity RVE results to evaluate effective isotropic elastic properties. The homogenized and specific stiffness of composite systems demonstrate significant improvements over HDPE, enabling significant reductions in shell thickness and weight while maintaining protective clearance margins. Carbon/Epoxy and Kevlar/Epoxy exhibited the highest specific stiffness and clearance-retention performance among the investigated materials, although matrix brittleness, manufacturing-induced fiber orientation bias, and cost remain important considerations. Threfore, discontinuous fiber composites offer a promising pathway toward lighter and more ergonomic industrial helmet shell concepts, with future work required in dynamic validation and prototype testing. The presented framework is intended for preliminary comparative material screening and should not be interpreted as a substitute for certification-level transient impact analysis or experimental validation.