Sparks Jessica L, Dupaix Rebecca B
Department of Biomedical Engineering, The Ohio State University, 270 Bevis Hall, 1080 Carmack Road, Columbus, OH 43210, USA.
Ann Biomed Eng. 2008 Nov;36(11):1883-92. doi: 10.1007/s10439-008-9555-3. Epub 2008 Aug 27.
An understanding of the mechanical deformation behavior of the liver under high strain rate loading conditions could aid in the development of vehicle safety measures to reduce the occurrence of blunt liver injury. The purpose of this study was to develop a constitutive model of the stress-strain behavior of the human liver in blunt impact loading. Experimental stress and strain data was obtained from impact tests of 12 unembalmed human livers using a drop tower technique. A constitutive model previously developed for finite strain behavior of amorphous polymers was adapted to model the observed liver behavior. The elements of the model include a nonlinear spring in parallel with a linear spring and nonlinear dashpot. The model captures three features of liver stress-strain behavior in impact loading: (1) relatively stiff initial modulus, (2) rate-dependent yield or rollover to viscous "flow" behavior, and (3) strain hardening at large strains. Six material properties were used to define the constitutive model. This study represents a novel application of polymer mechanics concepts to understand the rate-dependent large strain behavior of human liver tissue under high strain rate loading. Applications of this research include finite element simulations of injury-producing liver or abdominal impact events.
了解肝脏在高应变率加载条件下的力学变形行为，有助于开发车辆安全措施，以减少钝性肝损伤的发生。本研究的目的是建立人体肝脏在钝性冲击载荷下应力-应变行为的本构模型。实验应力和应变数据是通过使用落塔技术对12个未防腐处理的人体肝脏进行冲击试验获得的。一个先前为无定形聚合物的有限应变行为开发的本构模型被用来模拟观察到的肝脏行为。该模型的元件包括一个与线性弹簧和非线性阻尼器并联的非线性弹簧。该模型捕捉了冲击载荷下肝脏应力-应变行为的三个特征：（1）相对较硬的初始模量；（2）与速率相关的屈服或向粘性“流动”行为的转变；（3）大应变下的应变硬化。使用六个材料特性来定义本构模型。本研究代表了聚合物力学概念在理解人体肝脏组织在高应变率加载下与速率相关的大应变行为方面的新应用。本研究的应用包括对导致损伤的肝脏或腹部冲击事件的有限元模拟。
