Yu Mao, Manoogian Sarah, Duma Stefan M, Stitzel Joel D
Wake Forest University School of Medicine, USA.
Ann Adv Automot Med. 2009 Oct;53:257-70.
Motor vehicle crashes account for a large portion of placental abruption and fetal losses. To better understand the material properties of the human placenta, a Finite Element (FE) model of human placenta tissue was created and verified using data from uniaxial tension tests. Sixty-four tensile tests at three different strain rates of 7% strain/s, 70% strain/s, and 700% strain/s from six whole human placentas were used for model development. Nominal stresses were calculated by dividing forces at the grips by the original cross-sectional area. Nominal strains were calculated by dividing cross-head displacement by the original gauge length. A detailed methodology for interpreting experimental data for application to material model development is presented. A model of the tension coupon was created in LS-DYNA and stretched in the same manner as the uniaxial tension tests. The behavior of the material was optimized to the uniaxial tension test using a multi-island genetic algorithm. The results demonstrate good correlation between experiments and the model, with an average difference of 2% between the optimized FE and experimental first principal stress at the termination state. The material parameters found in this study can be utilized in FE models of placental tissues for behavior under dynamic loading.
机动车碰撞事故占胎盘早剥和胎儿死亡的很大一部分。为了更好地了解人类胎盘的材料特性，创建了人类胎盘组织的有限元（FE）模型，并使用单轴拉伸试验的数据进行了验证。来自六个完整人类胎盘的、在7%应变/秒、70%应变/秒和700%应变/秒三种不同应变率下的64次拉伸试验用于模型开发。名义应力通过将夹具处的力除以原始横截面积来计算。名义应变通过将十字头位移除以原始标距长度来计算。本文介绍了一种用于解释实验数据以应用于材料模型开发的详细方法。在LS-DYNA中创建了拉伸试样模型，并以与单轴拉伸试验相同的方式进行拉伸。使用多岛遗传算法将材料行为优化至单轴拉伸试验。结果表明实验与模型之间具有良好的相关性，在终止状态下，优化后的有限元与实验第一主应力之间的平均差异为2%。本研究中发现的材料参数可用于胎盘组织在动态载荷下行为的有限元模型。
