Hierarchical Experimental Characterization of the Human Rib Cage for Non-Lethal Projectile Impact Applications

Kinetic energy non-lethal weapons are designed to induce target compliance without causing severe injury and death. Computational torso models are a powerful tool used to evaluate the safety of new projectile designs before they are fielded, but the utility of such biomechanical models rely on experimental data for validation. To address this need, biomechanical test data from three different types of Post-Mortem Human Surrogate (PMHS) experiments are presented. In the first test series, rib velocities were evaluated in four PMHS torsos during impacts with a rubber projectile. In the second test series, flesh over the ribs of these same PMHS was removed, termed defleshed, to allow for direct impact to the ribs. By comparing the rib response between the first two test series, it was determined that the layer of flesh and muscle have a substantial effect on the rib response. The third test series evaluated the individual rib response by performing dynamic 3-point bend tests on the non-fractured ribs from the previously tested PMHS. The general trends across the three test series demonstrate that the intermediate rib levels (ribs 6-8) are structurally stiffer than the upper and lower ribs. Additionally, anterior rib cage impact locations tend to be more compliant than lateral and posterior locations. Results provide valuable validation data for future computational torso models by characterizing the response of the isolated rib, bare rib cage, and fleshed rib cage in an application for kinetic energy non-lethal weapons.