Material properties of the post-mortem colon in high-rate equibiaxial elongation.

Crash-induced injuries of the colon that occur in motor vehicle collisions include perforations, serosal tears, and ischemic colon injuries. To characterize the biomechanical response of the colon associated with these failure modes, high-rate equibiaxial stretch was applied to cruciate tissue samples harvested from four post-mortem human surrogates. Sample arms were gripped in four low-mass tissue clamps and simultaneous motion of four carriages applied equibiaxial stretch in four orthogonal directions. Tests were conducted to failure at a target strain rate of 100s-1 to investigate failure at rates expected to be experienced in motor vehicle collisions. Overhead high-speed video captured at 2500fps provided optical marker displacement data in a central region of interest. Marker positions were tracked using motion analysis software. Displacement data were input into LS-DYNA and average Green-Lagrange strain was calculated at 0.05ms time intervals. All data were truncated at tear initiation determined from high-speed video analysis. This manuscript presents the results of 26 colon tests conducted at an average strain rate of 67.1±17.9s-1. Average failure strain was 0.164±0.046 and 0.139±0.042 in the circumferential and longitudinal directions. Average maximum principal failure strain was 0.211±0.064. Material property data acquired in this study contribute to the biomechanical dataset useful for human body finite element model validation.