School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing, 100044, China.
Biomech Model Mechanobiol. 2020 Oct;19(5):1797-1808. doi: 10.1007/s10237-020-01309-4. Epub 2020 Feb 21.
Pediatric porcines have widely been used as substitute for children in biomechanical research. Previous studies have used entire piglet cranium when testing their properties. Here, the piglet craniums from the frontal and parietal locations were carefully dissected into spongy and cortical part, and tensile tests at different strain rates were then conducted on these two bone types. It is found that the elastic modulus, yield stress, and ultimate stress of the cortical bone were all significantly higher than those of the spongy bone. The ultimate strains of the cortical and spongy bone were similar. Overall, the effect of the position on the mechanical properties did not reach significance. Cortical bone strength from the frontal location was slightly higher than that obtained from the parietal location; however, spongy bone did not show this location difference. The mechanical properties of both the cortical and spongy bone are significantly strain-rate dependent. Specifically, the elastic modulus, yield stress, and the ultimate stress of the cortical bone increased by approximately 123%, 63%, and 50%, respectively, with strain rates ranging from 0.001 to 10/s. For spongy bone, increases were approximately 128%, 73%, and 77%, respectively. Ultimate strain decreased by approximately 37% and 7% for cortical and spongy bone, respectively. An elastic-plastic constitutive model incorporating with strain rate based on a combined exponential and logarithmic function was proposed and implemented into LS-DYNA through user-defined material. The developed model and the subroutine code successfully simulated the strain-rate characteristics and the fracture process of the bone samples.
儿科猪已被广泛用作替代儿童在生物力学研究。以前的研究已经使用整个仔猪颅当测试他们的属性。在这里，仔猪颅从前额和顶骨位置被仔细解剖成海绵和皮质部分，然后在这两种骨类型上进行不同应变速率的拉伸试验。结果发现，皮质骨的弹性模量、屈服应力和极限应力均显著高于海绵骨。皮质骨和海绵骨的极限应变相似。总体而言，位置对力学性能的影响没有达到显著水平。额骨皮质骨的强度略高于顶骨皮质骨；然而，海绵骨并没有显示出这种位置差异。皮质骨和海绵骨的力学性能都明显依赖于应变速率。具体来说，皮质骨的弹性模量、屈服应力和极限应力分别增加了约 123%、63%和 50%，应变速率范围从 0.001 到 10/s。对于海绵骨，分别增加了约 128%、73%和 77%。皮质骨和海绵骨的极限应变分别下降了约 37%和 7%。提出了一种基于组合指数和对数函数的包含应变速率的弹塑性本构模型，并通过用户定义材料将其实现到 LS-DYNA 中。开发的模型和子程序代码成功地模拟了骨样本的应变速率特性和断裂过程。
