A Three-Dimensional Nested Reinforcing Mesh in Elastomers for Crashworthy Applications

The advent of additive manufacturing allows for the design of complex 3D geometries that would otherwise be difficult to manufacture using traditional processes. Stereolithographic printing of geometrically reinforced structures gives promise for tunable energy-absorbing composite materials for impact applications. These materials may be suitable for applications in personal sport protection equipment such as knee-pads or helmets. The flexible nature of additive manufacturing can be easily scaled and modified to serve a variety of impact loading applications. In the present study, a three-dimensional nested array of ridged polymeric mesh with tiered high-temperature UV-cured polymer were embedded in a polyurethane matrix to form a new class of functional composite materials designed for multi-use low velocity impact events, and a single-use high velocity or high force impact event. The reinforcements were designed to absorb impact energy by the sequential bending, bucking, and failure of the layers of nested reinforcing members. The energy absorption capacity is further enhanced by the connective elastomer matrix which serves to retain the fractured mesh structure after initial breakage. The peak load is maintained at a relatively modest level while maximizing absorbed energy. Quasi-static loading tests were conducted to measure the peak load, total energy absorbing capability of the material. The energy absorption capability is measured using force-displacement plots and multiple interactions of material combination of reinforcement ring arrays. Tests with and without elastomer matrix, were conducted to understand peak load minimization and energy absorption character of the material.