单轴压缩下松质骨的应力率和蠕变性能

Stress rate and creep behaviors of cancellous bone under uniaxial compression

背景:松质骨是一种多孔、非均质、各向异性和具有黏弹性的结构,是骨的重要组成部分。它在负载传输和能量吸收方面起着十分重要的作用。所以对松质骨的力学行为进行研究具有重要意义。目的:探讨单轴压缩实验中应力率对松质骨性能的影响以及不同应力值下松质骨的蠕变行为。方法:以新鲜的猪股骨松质骨为实验材料,施加不同的应力率,至试样的压缩应变达到5%卸载;在松质骨表面施加恒定的应力水平,并保持7 200 s,以便观察其蠕变应变变化。结果与结论:(1)单轴压缩实验中,在同一应变条件下,随着应力率的增加,应力值、杨氏模量也增加;(2)在不同的加载率作用下,松质骨的压缩应力-应变曲线不重合,说明松质骨的压缩力学性能具有率相关性;(3)在蠕变实验中,蠕变应变随着压缩的应力的增加而增加,蠕变柔量随着应力的增加反而减少;(4)轴压缩和蠕变实验结果说明,应力率和恒定应力水平对松质骨的力学性能影响很大,以上结果可以为如何避免松质骨损伤提供参考依据。

BACKGROUND： Cancellous bone, as an important part of bone, is a kind of porous, inhomogeneous, anisotropicand viscoelastic structure, which plays a critical role in load transmission and energy absorption. Therefore,research on its mechanical properties is of great significance.OBJECTIVE： To investigate the compressive properties of cancellous bone at different stress rates and its creepbehaviors at different stress levels.METHODS： The fresh cancellous bone from pig femur was used as the material, and subjected to different stress until the compressive strain of sample was up to 5%. The constant compressive stress levels were loaded on the surfaceof cancellous bone for 7 200 s to observe its creep behaviors.RESULTS AND CONCLUSION： （1） In the uniaxial compression test, the stress values and Young’s modulus increasedwith the stress rate increasing under the same strain value. （2） The stress-strain curves of cancellous bone were differentat different loading rates, indicating that the mechanical properties of cancellous bone depend on the loading rate. （3） Inthe creep test, the creep strain increased with the increase of stress level, but the creep compliance decreased with theincrease of stress level. （4） These results suggest that the stress rate and stress level have significant influence oncompressive properties of cancellous bone, which provide reference for avoiding cancellous bone injury.