Rigid‐bar loading on pregnant uterus and development of pregnant abdominal response corridor based on finite element biomechanical model

Abstract

During pregnancy, traumas can threaten maternal and fetal health. Various trauma effects on a pregnant uterus are little investigated. In the present study, a finite element model of a uterus along with a fetus, placenta, amniotic fluid, and two most effective ligament sets is developed. This model allows numerical evaluation of various loading on a pregnant uterus. The model geometry is developed based on CT-scan data and validated using anthropometric data.Applying Ogden hyper-elastic theory, material properties of uterine wall and placenta are developed. After simulating the "rigid-bar" abdominal loading, the impact force and abdominal penetration are investigated. Findings are compared with the experimental abdominal response corridor, previously developed for a nonpregnant abdomen. "Response corridor" denotes a bounded envelope in response space, within which the system responses usually lie. Results show that at low abdominal penetrations (less than 45 mm), the pregnant abdomen response is highly compatible with the nonpregnant case. While, at large penetrations, the pregnant abdomen demonstrates stiffer behavior. The reason must be the existence of a fetus in the model. This reveals that the existing response corridors would not be reliable to be extended for a pregnant abdomen. Hence, response corridor development for a pregnant abdomen is a crucial task. In this study, a new fixed-back rigid-bar loading response corridor is proposed for a pregnant abdomen using the loadpenetration behavior of the developed model. This model and response corridor can help to study the pregnant uterus response to environmental loading and investigate the injury risk to the uterus and fetus. K E Y W O R D S abdominal response corridor, biomechanical model, finite element method, Ogden hyper-elastic material, pregnant uterus, rigid-bar loading

A Review of Biomechanics Analysis of the Umbilical–Placenta System With Regards to Diseases

“…Investigations of placenta mechanical properties are useful because their outcomes can be used for computational modelling of normal or diseased clinical events or during accidents to predict risks and outcomes. For example, a recent study developed a FE model of the uterus, placenta, fetus and amniotic fluid, and investigated the biomechanical effects of a blunt trauma on the pregnant abdomen (Irannejad Parizi et al, 2020 ). A hyperelastic model such as the Ogden model was commonly used in the past to describe the mechanical properties of the placenta during loading conditions (Hu et al, 2009 ; Pérès et al, 2014 ; Saw et al, 2018b ).…”