VCOM Research Day Program Book 2023

Faculty Research Biomedical

01 Protecting Pregnant Women in Car Crashes: Placenta and Uterine Material Testing and the Development of the First Computational Model of a Pregnant Occupant

Stefan Duma; Joel Stitzel; Sarah Manoogian Corresponding author: sduma@vt.edu

Virginia Tech

First, a total of 64 uniaxial tensile tests were performed on 6 whole human placentas. Following delivery, the tissue was stored in a saline solution and tested within 36 hours. The placenta tissue was prepared into tensile coupons and pulled to failure using a custom designed system of linear motors at one of 3 strain rates: 0.07 strains/s, 0.70 strains/s, and 7.00 strains/s. These rates represent a range of loading rates applicable to a motor vehicle crash. Local strain was calculated for each specimen using dot tracking with high speed video, and nominal stress was determined using original cross sectional area measurements combined with the load sensor data from each grip. Bi-axial tests were performed on human uterine tissue with similar strain rates. These material properties were used to create a finite element uterine model of a 7-month pregnant woman and integrated into a multibody human model. Unrestrained, three-point belt, and three-point belt

plus airbag tests were simulated at speeds that ranged from 13 to 55 km per hour. Peak uterine strain, as determined by the model, correlated well with the risk of fetal death, as determined by investigations of car crashes. The strain in the uterine wall exceeded the limits of the tissue in simulations of no restraint at 35 km per hour and three-point belt tests at 45 and 55 km per hour. The safest restraint for the pregnant driver is the combination three-point belt and airbag. The model is a good first step toward the prediction of the risk of fetal death and verified experimental findings that note the importance of proper restraint use for the pregnant occupant.

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