Investigation of energy absorption characteristic of ceramic fiber reinforced elastomer composites

Head protection from impact events for participants in contact sports or other activities is of current interest. Custom designed and synthesized material systems which effectively reduce the peak force transmitted to the individual and absorb a substantial portion of the impact energy are highly desirable. In applications in which recovery time of the material is not a primary concern, multiple means of energy absorption, including deformation and fracturing of the reinforcement material, may be suitable. In the present study, new composite material systems using a urethane elastomer matrix reinforced with glass and unidirectional carbon fiber rods were synthesized and subjected to compression loading along the fiber direction. The constituent fiber rods absorbed energy either through plastic deformation, buckling, or fracturing during compression loading. The effect of different reinforcement material, configuration, and length were physically tested. A cascading failure mode was achieved by embedding fibers of varying length in the matrix. This triggered successive failure events as the primary load was transferred from the longest rod to each successive shorter rod. The elastomer matrix was also experimentally characterized quasi-statically. A thin outer polymer layer further constrained the elastomer composite and allowed for fine adjustment and optimization of its crushing characteristics.