Dynamic Biaxial Tissue Properties of Pregnant Porcine Uterine Tissue

Automobile crashes are the largest single cause of death for pregnant females and the leading cause of traumatic fetal injury mortality in the United States. Current research for pregnant occupant safety utilizing computational models is limited by available pregnant tissue data. The purpose of this study is to collect experimental data from biaxial tissue tests on pregnant uterine tissue at a dynamic rate. Experimental tests were completed on pregnant porcine uterus which was chosen as a surrogate for the human pregnant uterus given its similarity and availability. Biaxial dynamic tensile tests were performed using a custom-designed system of linear motors to pull a cruciform-shaped specimen in tension simultaneously with four tissue clamps. The test series included 23 tests with corresponding peak stress and strain measurements of the central region of the specimen where optical markers tracked local displacements. The specimen was loaded at a rate of 0.7 strains per second to match the uterine strain rate in a motor vehicle crash. Experimental results include peak stresses and peak strains for the pregnant uterine tissue in tension. When loaded biaxially, the circumferential peak stress is 500 ± 219 kPa with a corresponding peak true strain 0.30 ± 0.09 and the longitudinal peak stress is 320 ± 176 kPa with a corresponding peak true strain 0.30 ± 0.09. This material information can be implemented in pregnant occupant models to evaluate the uterine tissue response to impact loading scenarios.