School of Engineering, Anhui Agricultural University, Hefei, People's Republic of China.
PLoS One. 2022 Jul 27;17(7):e0271301. doi: 10.1371/journal.pone.0271301. eCollection 2022.
Bone fracture is an extremely dangerous health risk to human. Actually, cortical bone is often subjected to the complicated loading patterns. The mechanical properties and deformation mechanism under the complicated loading pattern could provide a more precise understanding for the bone fracture. For this purpose, the mechanical response and multi-scale deformation mechanism of cortical bone material were investigated by in-situ experimental research using the compression-torsion coupling loads as an example. It was found that the torsion strength and shear modulus all decreased under the compression-torsion coupling loads than single torsion load. This indicated bone would suffer greater risk of fracture under the compression-torsion coupling loads. Based on in-situ observation, it was found that the rapid reduction of the anisotropy of bone material under the compression load was the potential influencing factor. Because of the redistribution of the principal strain and the variations of cracks propagation, the comprehensive fracture pattern containing both transverse and longitudinal fracture was shown under the coupling loads, and finally resulted in the reduction of the torsion properties. This research could provide new references for researches on mechanical properties of cortical bone material under complicated loading patterns.
骨折对人类健康是一个极其危险的健康风险。实际上，皮质骨经常受到复杂的加载模式的影响。在复杂加载模式下的力学性能和变形机制可以为骨骨折提供更精确的理解。为此，通过压缩-扭转耦合载荷的原位实验研究，研究了皮质骨材料的力学响应和多尺度变形机制。结果表明，在压缩-扭转耦合载荷下，扭转强度和剪切模量均低于单一扭转载荷。这表明在压缩-扭转耦合载荷下，骨骼更容易发生骨折。基于原位观察，发现压缩载荷下骨材料各向异性的迅速降低是潜在的影响因素。由于主应变的重新分配和裂纹扩展的变化，在耦合载荷下表现出既有横向又有纵向的综合断裂模式，最终导致扭转性能的降低。这项研究为复杂加载模式下皮质骨材料力学性能的研究提供了新的参考。
